STRESS

The concept of stress as a change in the environment that results in an internal response in living organisms can be traced to the nineteenth-century ideas of the physiologist Claude Bernard (1813–1878). Initially, the stress response involves important adaptive changes throughout an organism that are necessary to restore homeostasis, a term coined by Walter Cannon (1871–1945) to describe the internal bodily balance in physiological systems. Living organisms make adjustments within their cells to internal and external sources of stress in order to adapt, maintain function, and survive challenges to homeostasis. In contrast to the adaptive role of the stress response, Hans Selye (1907–1982) discovered that stress-related diseases were often the result of chronic effects of stress. Thus, the stress response is a double-edged sword with both beneficial and detrimental effects for the whole organism. Failure to mount an adequate stress response, or to terminate the stress response, or unrelenting stress results in additional threats to homeostasis over and above the stress that elicited the response in the first place. This is especially true during aging, when it becomes more difficult to maintain homeostasis due to accumulated damage and inadequate repair of molecules and cells. In his 1992 book on stress and aging, Robert Sapolsky pointed out that theorizing by gerontologists about stress focuses on both the decreased ability of older organisms to respond to stress and an increased incidence of stress-related diseases during aging.

Different stressful conditions produce a similar stress response, which Selye named the general adaptation syndrome. The ability of organisms to adapt to stress is regulated by the integration of the nervous, immune, and endocrine systems; is mediated by hormones; and is ultimately played out at the level of cells and molecules. Hence, stress has a prominent role in cellular aging. Cells have to withstand and respond to major types of stress in their environment, including genotoxic, heat shock, and oxidative stress. Old cells are more vulnerable than young cells to stresses in their environment. Lower organisms with short life spans serve as experimental models to study the effects of stress on cellular responses in relation to aging. In 2001, a Swedish group using fruit flies to screen for bacterially induced genes found a new humoral factor, Turandot A, that is released systemically in response to many types of stress and also at advanced ages. Overexpression of Turandot A helps adult fruit flies to survive heat stress without inducing heat shock or immune genes or its own synthesis, and therefore may act through a separate pathway or at a point where many types of stress converge. Cellular defense mechanisms important in aging include DNA repair, detoxification of chemicals, production of antioxidants and heat shock proteins, and even cell suicide as a result of initiating a cell death program. The effects of the major types of stress on cellular aging will be taken up in succeeding sections, following a general discussion of the stress response in relation to development of disease and altered function during aging.

Stress response

The actions of counterregulatory hormones that are released as part of the stress response are important in restoring the balance in physiological systems. Stress increases the release of physiological mediators from the autonomic nervous system and adrenal glands, including fast-acting catecholamines and slow-acting steroids (mainly glucocorticoids), that participate in the adaptive response. The signal to release stress mediators into the blood is first transmitted from a physical (e.g., heat) or psychological (e.g., predator odor) stress through the nervous and immune systems to the brain. These signals are integrated in the brain, where they are converted into defensive behaviors (reflex withdrawal of a limb or running away from a predator) and hormonal responses that are important for survival. For example, glucocorticoids mobilize energy (glucose) stored in the liver for use by muscle, and they inhibit processes (e.g., growth and reproduction) that are not necessary for adaptation. Glucocorticoids are essential for surviving severe stress, but their effects exerted throughout the body can be damaging if the stress is prolonged, and may eventually result in disease. There are controls in place to prevent excess secretion of glucocorticoids, called a negative feedback loop. After the stress-induced increase in glucocorticoids in the blood, these hormones turn down their own production by decreasing the synthesis of factors made in the hypothalamus of the brain and in the pituitary gland that promote their synthesis and secretion from the adrenal gland.

Age-related changes in the adrenal glands and nervous system contribute to a decreased ability of elderly individuals to adapt to stress. Since glucocorticoids regulate natural defense mechanisms (e.g., immunity and inflammation) with both permissive and suppressive actions to protect against stress, decreased sensitivity to glucocorticoids may increase vulnerability to stress. Excess production of glucocorticoids by the adrenal glands could also be a culprit, as proposed by Sapolsky in his glucocorticoid cascade hypothesis, since elevated levels of this steroid hormone do not always return to baseline as quickly in older individuals after stress. Therefore, catabolic effects of glucocorticoid excess may contribute to the development of conditions that are prevalent in elderly persons, including immune suppression and cancer, muscle atrophy, osteoporosis, diabetes, and memory decline. An association between reduced negative feedback regulation of the hypothalamic-pituitary-adrenal axis during aging, especially in the face of stress, disease, and other forms of challenge (exercise, driving test) supports this hypothesis. Based on studies supported by the John D. and Catherine T. MacArthur Foundation through its Research Networks on Successful Aging and on Socioeconomic Status and Health, the interplay of these same factors is also associated with cognitive decline (learning, memory, and language loss).

Since the findings of neuron loss by Philip Landfield in the late 1970s, much has been made of the harmful effects of glucocorticoids in the hippocampus, a part of the brain that is involved in learning and memory. Follow-on studies by Robert Sapolsky and Michael Meaney beginning in the middle 1980s, when they were doctoral students in Bruce McEwen’s laboratory at the Rockefeller University, suggested that chronic stress and excess production of glucocorticoids resulted in the death of hippocampal neurons during aging, thus contributing to age-related memory loss. However, memory impairment in old rats correlates better with loss of connections between neurons than with the loss of principal neurons in the hippocampus. Studies performed by McEwen’s group between 1995 and 2000 demonstrate that chronic stress induces synaptic loss and atrophy of the hippocampus similar to that which occurs during aging. The reversibility of these effects in rodents may help to explain how humans who are routinely treated with high doses of glucocorticoids for long periods do not seem to have extensive hippocampal damage and memory impairment. Beginning in 1987, researchers at McGill University in Canada conducted a longitudinal study sampling individuals over a three- to six-year period, and found that memory impairment occurred only in a sub-group of healthy elderly individuals with both a high and an increasing cortisol (glucocorticoid) level. The increasing inability of these individuals to decrease their hormone level over time is an indication of failure in the nervous and endocrine systems. Together with the MacArthur Foundation studies conducted by Teresa Seeman, this work highlights the importance of individual variability in response to stress. The good news is that some deleterious effects of stress may be reversible even in elderly persons. Since psychosocial factors are important in how an individual responds to stress, it may be possible, with effective stress management, to decrease excess glucocorticoid production in humans.

Glucocorticoid excess and chronic stress are unlikely to be the only factors that result in an inability to adapt to stress during aging. In a 1998 article published in the New England Journal of Medicine, McEwen suggests a revision in the approach to understanding the relationship between changes in the environment and biological responses to emphasize both beneficial and detrimental effects of stress mediators and, in particular, the costs of adaptation to stress. Short-term beneficial effects result in allostasis, which means the capacity to adapt or restore homeostasis through change, whereas long-term detrimental effects constitute an allostatic load (the cost of having to adapt to challenges and changes in the environment). By measuring allostatic load at earlier ages, it may be possible to identify risk factors (e.g., overactivity of the hypothalamic-pituitary-adrenal axis) that result in late onset diseases (e.g., Type II diabetes, dementia). Since cellular responses are of primary importance in adaptation to stress, it is necessary to determine how stress mediators regulate cellular responses to achieve allostasis during aging. Age-related changes in cellular constituents involved in these responses may result in an increased allostatic load, thus contributing to a reduced capacity of older organisms to adapt and restore homeostasis. Three major types of stress are discussed in the following sections in relation to cellular aging changes.

Genotoxic stress

The integrity of the genome and the faithful transmission of the genetic material it contains to the next generation are important for survival of species. Similarly, the integrity of genomic and mitochondrial DNA and the transmission of the information they contain are important for the survival of individuals. DNA damage in the form of mutations or genomic instability result from genotoxic stress caused by exposure to toxic agents, including the sun’s ultraviolet rays, background ionizing radiation, chemicals in food and the environment, and highly reactive molecules produced within cells during metabolism. Similar types of DNA damage occur in response to various agents and include mutations, removal of bases and nucleotides, formation of dimers, strand breaks, cross-links, and chromosomal aberrations. Some of these types of damage accumulate in nuclear or mitochondrial DNA during aging (e.g., point mutations, single-strand breaks, DNA cross-links, additions/deletions, oxidative damage, and methylated bases). In a chapter in Hormones and Aging (1995), Suresh Rattan reviews DNA damage and repair and the evidence for genomic instability, loss of cell proliferation, production of altered proteins, and altered cellular responsiveness as a result of damage to DNA in cells and genes during aging. The ability to repair DNA damage may be related to length of the life span, since humans repair DNA faster than mice, but is not always related to maximum life span because premature aging is not always associated with a reduced capacity to repair DNA. Although there is little evidence to suggest an overall decline in the capacity of cells to repair DNA during aging, thus far only a few DNA repair pathways have been studied in any detail.

The sensitivity of cells to genotoxic stress increases during aging. Age-related deficits in protein synthesis and the responsiveness of cells to stress, decreased cell-cell communication, and inefficient signal transduction may render old cells less able to withstand stress. The ability to repair DNA may be compromised by other toxic agents, leading to loss of function in molecules and cells and shortening of life span. A decrease in the ability to repair genomic DNA may lead to increased incidence of cancer in elderly persons. Similarly, mitochondrial DNA damage and mutations increase with aging, as does susceptibility to age-related diseases such as diabetes, Parkinson’s, and Alzheimer’s disease. In 2000, Jay Robbins and colleagues at the National Cancer Institute and a European group independently established a link between faulty DNA repair caused by defects in nucleotide excision repair and neurodegeneration, a link that was proposed by Robbins twenty-five years previously. Some patients with xeroderma pigmentosum show, in addition to greatly exaggerated risks of skin cancer, premature neuron death and DNA lesions similar to those in Alzheimer’s disease. Although cancer susceptibility and neuron death can both result from defects in DNA repair, the precise mechanisms may differ. Mouse models that are deficient in nucleotide excision repair also show increased incidence of tumors in response to genotoxic stress and a decreased life span, but they have reduced neurological deficits compared with human syndromes. These mice are being used to understand the involvement of DNA repair in genotoxic sensitivity and cancer susceptibility and in the process of aging.

Studies pioneered by Richard Setlow in the 1970s showed a correlation between DNA repair and species life span, but were largely based on crude measures of DNA repair. In 1998, using improved techniques that allowed specific genes to be assessed, Arlan Richardson’s group in San Antonio, Texas, demonstrated that nucleotide excision repair of DNA in liver cells from old rats challenged with UV irradiation depended on whether the strand was actively transcribed or silent. The rate of repair of the transcribed strand of albumin DNA (transcription-coupled repair) was 40 percent less compared with young rats, but the extent of repair was not different at the end of the experiment. This was in contrast to the extent of repair of the silent strand, which was 40 percent less in old rats compared with young rats. Thus accumulation of DNA damage and mutations during aging may occur in nontranscribed regions of the genome. Richardson’s studies also showed that both age-related deficits in DNA repair could be reversed by caloric restriction, which retards aging by increasing life span and reducing or delaying many of the diseases associated with aging.

Beginning in the 1990s, modern approaches to screening for changes in the expression of genes and proteins have fueled searches for cellular responses to genotoxic stresses, which may hold clues for understanding the process of aging. Hundreds of genes are induced in mammalian cells, most of which represent general responses to cell injury (e.g., induction of the immediate early genes, c-fos and c-jun ). Many DNA-damaging agents and their activated signaling pathways converge on the transcription factor p53, which functions as a sensor for DNA damage and regulates the transcription of hundreds of genes. However, changes in a few critical genes, such as those involved in DNA repair or information transfer, may underlie genomic instability during aging. Candidates are poly(ADP-ribose polymerases, or PARPs, a family of nuclear enzymes, some of which bind nicked DNA and guard the genome by regulating DNA repair and cell death. The activity of PARPs in white blood cells from thirteen mammalian species correlates with life span, yet knockout of the PARP-1 gene confers resistance to stroke and diabetes. Other candidates are helicases (DNA unwinding enzymes) or their associated proteins. Helicases are involved in DNA repair and regulation of transcription, and are mutated in premature aging syndromes. Overlapping aging phenotypes in some helicase disorders and normal aging implicate common pathways, especially transcriptional regulation. Further studies of PARPs and helicase enzymes and their functions during aging could establish a stronger link with cellular or organismal aging. Mouse models that are deficient in nucleotide excision repair also show increased incidence of tumors in response to genotoxic stress and a decreased life span, although they have reduced neurological deficits compared with human syndromes. These mice are being used to understand the involvement of DNA repair in genotoxic sensitivity and cancer susceptibility, and in the process of aging.

Heat shock stress

Nonlethal heat stress induces a characteristic set of proteins in cells that are called heat shock proteins. This stress response is ancient and highly conserved throughout living organisms. Many types of stress in addition to mildly elevated temperature can induce heat shock proteins. Heat shock proteins act as molecular chaperones by helping cells to repair or remove damaged proteins and by participating in the intracellular transport of newly synthesized proteins. Therefore, they are important regulators of cellular adaptation to stress. An important function of heat shock proteins in relation to aging is their ability to confer resistance or tolerance to future insults. The mechanisms for protection against future stresses are poorly understood but may involve the ability of heat shock proteins to promote cell survival by interfering with a cell death program that leads to cell suicide. The synthesis of heat shock proteins is also linked to neuroendocrine responses to stress. For example, elevated glucocorticoid secretion can induce specific heat shock proteins in different cells as a beneficial effect of the stress response. Their role in protein degeneration and the stress response is highlighted by their accumulation in plaques and tangles, the brain deposits associated with Alzheimer’s disease pathology.

In the 1990s, researchers in the field of aging, including Richardson, Nikki Holbrook, and Marcelle Morrison-Bogorad, thought that the decreased ability of aged individuals to maintain homeostasis in the face of insults could be due to inadequate cellular responses to stress like the heat shock protein response. They found that the induction of heat shock proteins in response to stress decreases with age. Richardson’s group found that the induction of heat shock protein 70 by heat stress in liver cells cultured from old rats was reduced by 50 percent compared with young rats. Furthermore, the decrease in heat shock protein 70 induction occurred at the transcriptional level of regulation and was dependent on reduced binding of a transcription factor to the promoter of the heat shock protein 70 gene. Holbrook’s group at the National Institute of Aging used transplantation studies to determine whether the deficit in heat shock protein 70 response in blood vessels was due to the age of the tissue or to the environment. Transplantation of old vessels to a young host restored their response, and transplantation of young vessels to an old host resulted in a reduced response. In the case of blood vessels, heat exposure produced less of an increase in blood pressure in old rats than in young rats, which resulted in less heat shock protein 70 induction. In other circumstances, hormonal or metabolic changes that occur during aging could result in aged cells receiving less of a stimulus to induce the response. Age-related changes could also reduce the effectiveness of the heat shock proteins. For example, genotoxic stress can damage heat shock proteins in the cells of aged individuals due to mutated DNA, errors in translation of mRNA into protein, or reduced repair, and also diminish their role in stress tolerance. Therefore, the environment is a factor that should be considered in interpreting age-related differences in the response of cells to stress.

Richardson and Holbrook proposed in a 1996 review that the widespread reduction in stress-induced heat shock protein 70 expression in aged organisms indicates the importance of this response in both cellular and organismal aging. Consistent with this hypothesis is the ability of caloric restriction to restore the stress-induced heat shock response during aging. Furthermore, mutants that increase life span in nematodes also overexpress heat shock proteins in response to stress, and overexpression of heat shock protein 70 sometimes results in increased life span in fruit flies. Basal levels of heat shock protein 70 are usually not different between young and old individuals, but other members of the heat shock protein family do increase during aging in mice, fruit flies, and nematodes. Age-related increases in basal heat shock protein expression may be a response to accumulated damage and oxidative stress. Therefore, as proposed by Gordon Lithgow and Tom Kirkwood in 1996, heat shock proteins that function as molecular chaperones may regulate organismal aging.

Oxidative stress

Oxidative stress occurs when highly reactive molecules called free radicals overwhelm the cell’s natural defenses against their attack. It is a battle that is fought in cells every day. Each cell in the body produces billions of free radicals a day, and some of them are used in physiological relevant reactions; oxygen itself is a free radical. Free radicals derived from oxygen are formed in the course of aerobic life when chemical bonds are broken during the production of energy in the mitochondria. Usually free radical reactions are controlled by free radical scavenging molecules that remove excess free radical scavenging molecules and antioxidants that neutralize free radicals. Chemical reactions with free radicals occur in all living organisms and can amplify their effects in the cell. Under conditions of oxidative stress, free radicals attack other molecules and form molecules that are foreign to cellular machinery (e.g., cross-linking of proteins makes them resistant to proteases), so they fail to turn over, accumulate, and eventually impair function by slowing down physiological processes. Free radicals are also produced in response to genotoxic stress by exposure to ionizing radiation from ultraviolet rays of the sun, chemical pollutants, and smoking.

Denham Harman first proposed the role of oxygen-derived free radicals in the aging process in 1956. An introduction to the concepts of free radical production and oxidative stress during aging is presented in a 1992 Scientific American article titled ‘‘Why Do We Age?’’ A more in-depth review by Toren Finkel and Nikki Holbrook appeared in Nature in 2000 as part of a series titled ‘‘Ageing.’’ During aging an imbalance occurs between production of free radicals and antioxidant defenses, resulting in an accumulation of free radicals and oxidative attack or damage to DNA, protein, lipids, membranes, and mitochondria. Although enzymes that repair proteins, lipids, and DNA are produced, the ability to repair cellular oxidative damage decreases with age, resulting in a reduced ability of old cells to withstand oxidative stress. The repair enzymes may be less efficient because they, too, are attacked or cross-linked and the whole system breaks down, resulting in impaired function and susceptibility to disease. Furthermore, free radicals build up over time and can damage the mitochondria, resulting in less energy production. The decrease in energy results in oxidative stress and a further increase in free radicals, which eventually damage other cellular components. Oxidative damage to organelles results in cellular injury and cell death. Free radical reactions with cellular components and cross-linking of proteins and DNA increase with aging. In addition, various types of stress, including injury and disease, amplify these reactions during aging. An effect of aging on oxidative damage to nuclear and mitochondrial DNA was first reported by Bruce Ames’s laboratory. Richardson’s group showed that the increase in DNA oxidative damage during aging was not due to inability to repair the damage but, rather, to increased sensitivity to oxidative stress. Richardson’s group also showed that caloric restriction could reduce the levels of DNA oxidative damage in aged rats, supporting the role of oxidative stress in the process of aging.

Evidence from mutants in fruit flies and nematodes, reviewed by Finkel and Holbrook, supports a role for molecules that are capable of scavenging free radicals or of decreasing the accumulation of free radicals and oxidative stress in extension of life span. Surprisingly, mutants with altered life span can have their normal life span restored by expression of the normal protein specifically in neurons, suggesting that neurons control how long an organism can live. Overexpression of superoxide dismutase, an enzyme that neutralizes the superoxide free radical, in motor neurons can extend life span by up to 48 percent in fruit flies that also exhibit resistance to oxidative stress, and partially rescues the normal life span of a short-lived superoxide dismutase null mutant in a dose-responsive manner. The long life span of age-1 and daf-2 mutants rescued with expression of these genes only in neurons is also associated with higher levels of free-radical scavenging enzymes and protection of neurons from oxidative damage. According to Gabrielle Bouliame, whose group performed the experiments on fruit fly motor neurons, it is possible that these neurons, through neuroendocrine signals, regulate the functional reserve or adaptive capacity of tissues in the organism, which in turn influences life span.

Theories of aging

The process of aging is characterized by imbalances that result in dysfunction manifested at different biological levels and culminate in death of the organism. Some of these changes are programmed and begin from within the cell, and others occur in response to the intrinsic or extrinsic environment. Stress is an important concept in many theories of aging, including systemic, cellular, and molecular theories, and especially in those which explain aging in terms of ability to maintain and restore homeostasis. However, the effects of prolonged stress on an individual may be due to the development of disease and not a result of normal aging process. Questions that remain are whether the effects on aging are due to stress or to stress-induced disease processes that overwhelm the defense or repair systems, and are then life-threatening in old individuals. With these caveats in mind, the stress response is important in the neuroendocrine theory of aging and oxidative stress is important in the free radical theory of aging.

New humoral or systemic factors are being described that differentially regulate the cellular stress response during aging. As shown by studies from Dan Hultmark’s group in Sweden, a humoral factor that increases heat shock protein 70 prevents cell death and restores stress resistance in old cells. These factors implicate neural and endocrine signals in the control of aging. The neuroendocrine theory of aging proposes that the ability to respond to stress is an important factor in reduced ability to maintain homeostasis during aging. Furthermore, the control of homeostasis becomes disorganized during aging, resulting in loss of adaptive capacity, decreased resistance to stress, and increased allostatic load. Thus, aging is the price the organism has to pay for surviving stress. Convincing evidence supports the theory that free radicals and oxidative stress play an important role in the aging process, and indicates that oxidative damage to neurons may be related to life span and aging, as well as to neurodegeneration. This knowledge may be used to find ways of slowing aging and increasing average life span in humans.

Rate of Aging

Aging is a complex process and is unlikely to result from a single cause or a single gene. Conditions that slow or accelerate aging and genes that control the rate of aging provide clues about what causes aging. Although aging is not equal to life span, genes that regulate life span are often important in resistance to stress and may be able to slow aging: superoxide dismutase prevents the accumulation of free radicals, and nucleotide excision repair enzymes repair DNA. Furthermore, cell stress resistance is correlated with maximum life span across species. Based on the evolutionary theory of aging, Thomas Kirkwood and Steven Austad predict that key enzymes that regulate the rate of aging are those involved in maintenance and repair. A gene involved in maintenance and repair that can regulate the rate of aging is exemplified by stress-induced p53. Free radicals, oxidative stress, DNA-damaging agents, and environmental stresses (including heat) result in increased activation of p53. The activation of p53 can lead to DNA repair, to cell cycle arrest in order to limit DNA replication (cellular replicative senescence), or to cell death, which is how it acts as a tumor suppressor to prevent cancer. In a study published in Nature in January 2002, transgenic mice that express mutant-activated p53, which augments wild-type p53 activity, show a resistance to tumors and early signs of some aging phenotypes, including reduced life span, osteoporosis, and multiple organ atrophy. Importantly, these mice also display a reduced ability to tolerate stress, as shown by delayed wound healing and reduced recovery from stress in old mice. These data suggest a role for the stress-induced cellular p53 response in organismal as well as cellular aging and in acceleration of some aging changes.

Caloric restriction not only retards aging but also reverses the effects of stress during aging by putting cells in a survival mode. It decreases free radical production and oxidative stress, reduces the load of damaged molecules, decreases sensitivity to genotoxic stress, and postpones declines in DNA repair. Caloric restriction also alters the expression of genes that regulate damage and stress-response pathways. Both heat shock stress and exposure to mild oxidative stress can result in hormesis, a beneficial effect that occurs in response to very low doses of agents that are toxic at higher doses. Minimal stress not only increases survival in fruit flies and nematodes but also increases life span. Caloric restriction also results in hormesis and may slow the aging process by inducing a mild stress response, including increases in heat shock protein 70 and glucocorticoids that afford protection against stress. In contrast, premature aging syndromes with shortened life spans result from single gene mutations that result in genomic instability, inability to repair DNA, and some of the phenotypes of aging.

The psychosocial environment determines how an individual perceives stress, and coping ability plays a role in age-associated functional decline. Few studies of stress focus on the oldest old (greater than eighty-five years), although they have frequent physical, emotional, and social changes that decrease their sense of control and require adaptation to stress. It is interesting that within this group are centenarians who have greater functional reserve and adaptive capacity, enabling them to overcome a disease or injury or to cope with stresses more effectively.

Nancy R. Nichols

See also Nutrition: Caloric Restriction; Theories of Biological Aging: DNA Damage;

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Stress

BIBLIOGRAPHY

The concept of stress has come into increasing prominence in the biological and social sciences since World War ii. As in the use of the term in engineering, where it is applied to forces exerted on inorganic objects, “stress” suggests excessive demands made on men and animals, demands that produce disturbances of physiological, social, and psychological systems. The important biological, social, and psychological consequences of stress galvanize scientific interest and mobilize efforts to understand and control them. The entire subject has been reviewed and analyzed recently by Lazarus (1966).

”Stress,” as the term is used in the social sciences, has been applied to phenomena as diverse as metabolic imbalance following surgery, failure to succeed in an experimental task, personal bereavement, psychopathological reactions connected with military combat or life in a concentration camp, and the societal disruptions produced by naturally occurring disasters. The term “stress” is thus loose, in that it is applied to a host of phenomena related only by their common analogy with the engineering concept, and, at the same time, exceedingly broad, in that it covers phenomena at the physiological (Selye 1956), social (Smelser 1962), and psychological (Lazarus 1966) levels of analysis that may be described in a common theoretical language of causes, intervening processes, and effects. Whether phenomena as different as metabolic imbalance, symptoms of psychopathology, and social disturbance have anything in common beyond this loose analogy is an open issue, but the idea of stress as applied to a host of biological and social phenomena has intuitive appeal to laymen and scientists alike and gives the appearance to many of permitting the synthesis of these phenomena within, some common system of thought. The term “stress” has, at the very least, the value of being a generic one, unifying a wide variety of phenomena, concepts, and empirical research.

This article deals with psychological stress. Within the field of psychological stress there are several distinct problem areas. One concerns the processes and conditions that produce stress reactions. A second has to do with the ways in which the conditions resulting in psychological stress are coped with. A third deals with the measurement of the reactions and with the links between these reactions and the intervening stress processes postulated by theory.

Psychological stress phenomena. Before we deal with key theoretical and methodological issues, let us consider the phenomena that define the subject matter of psychological stress so that we have some common empirical bases for a discussion of concepts and findings. What kinds of stimulus conditions have been studied as determinants of psychological stress reactions, and what reactions in response to these stimuli define the field?

Stimuli eliciting psychological stress . The following stimulus conditions are typical of research into stress under natural circumstances: military combat, imprisonment in concentration camps, isolation as produced, for example, by shipwreck, the imminence of death from such diseases as cancer and heart attack, the prospect of major surgery, the anticipation of a crucial scholastic examination, the death of close family members, the onslaught of and adaptation to such crippling diseases as paralytic polio, and warnings or actual impacts of various disasters, such as floods, tornadoes, and explosions. [See Disasters.]

Many types of experimentally produced, laboratory stimulus situations have also been employed in the study of psychological stress. Some typical ones are making the subject believe he has neurotically misperceived reality, producing failure on the part of the subject in the performance of some skilled or intellectual task, ridiculing or verbally assaulting the subject, creating the belief in the subject that he is in danger of electrocution or likely to sustain severe bodily injury, creating in the subject the anticipation of painful electric shock, and having the subject watch a disturbing motion picture.

These stimulus conditions have been chosen by research workers mainly because of the psychological and physiological disturbances they are known to create and not because the researchers want to test a controversial theoretical analysis of psychological stress processes. They are worthy of study for their own sake as well as aiding in the general understanding of how people react to various forms of stress. Experimental work on stress is designed to create laboratory analogues of processes or effects that are observed in natural situations, in order to study those processes and effects under better controlled conditions (see Lazarus & Opton in Spielberger 1966).

Characteristics of the person that interact with the stimulus conditions have been heavily emphasized in both the naturalistic and the experimental approaches. A frequent observation under all these conditions is that individual differences in reaction loom very large, and personality variables that account for this have been sought with rather limited success (Opton et al. 1967).

Response variables indicating stress . With regard to response, four classes of measures have been employed as indicators of stress reaction. Three of these are the classical, defining attributes of (negatively toned) emotional states: disturbed affect as reported by the individual (for example, fear, anxiety, anger, and depression); motor-behavioral patterns that permit the observer to make inferences about such emotions (for example, postures, facial patterns, flight and attack); and physiological correlates of emotion (for example, secretions of adrenal hormones, such as epinephrine, norepinephrine, and hydrocortisone, and autonomic nervous system reactions, including increased skin conductance, heart rate, blood pressure, and skin temperature, to name a few of the most common).

Cognitive functioning. The fourth category of stress-reaction measure, disturbance in cognitive functioning, has been employed to indicate stress reactions because impairment of skilled performance and of perception, learning, and judgment is often observed under stress-producing conditions. However, impairment is by no means inevitable; many studies have revealed significant improvement in functioning under stress. Thus, paradoxically, conditions of stress can be viewed as being damaging to performance but as also being capable of improving performance. The conceptual and methodological aspects of this problem have been discussed at considerable length by Lazarus, Deese, and Osier (1952) and more recently by Sarason (1960).

One of the generalizations usually accepted is that the disruption or facilitation of performance appears to depend on such factors as the nature of the task, the characteristics of the individual who is exposed to the stress conditions, and the intensity of stress. Specifically, difficult or complex tasks requiring great concentration or abstraction are more vulnerable to the effects of stress than simple, repetitive tasks; some individuals appear more vulnerable to impairment than others, although it is not at all clear which personality variables are involved; and only under mild or moderate degrees of stress does facilitation of performance appear to take place.

Attempts at understanding impaired functioning . The problem of accounting for impairment of functioning under stress conditions poses controversial questions that have prompted much theorizing and empirical research. Two contrasting points of view are examples of attempts to understand the principles underlying performance changes with stress.

One of these positions is represented by Farber (1955), who emphasizes the drive properties of the anxiety that is produced by stress conditions. Following Hullian reasoning, he argues that high drive, or high anxiety, will increase the strength of all responses, correct as well as incorrect ones, in task performances connected with learning. If the task is difficult or complex—that is, if it contains many competing responses—high drive will impair performance, because a larger number of incorrect, competing responses will be facilitated. If the task is simple and contains small numbers of competing responses, performance will be facilitated by high drive, since comparatively fewer incorrect responses will be strengthened. An active controversy over this view exists. Sarason (1960) has reviewed the literature and the arguments, citing studies with findings not consistent with this formulation and noting critiques of the drive viewpoint. [See Drives.]

An alternative class of viewpoints about the effects of stress on performance is represented by Korchin (1964) and Easterbrook (1959), who have argued that impairment of performance results from the narrowing or restricting of perception that occurs under stress. Just why this restriction of the perceptual field occurs is not entirely clear. An interpretation can be made in terms of interference or in motivational terms. In terms of motivation, the individual is motivated under stress to select from the environment only that which is relevant to the danger. Thus, he may ignore features of the situation that seem momentarily irrelevant, ultimately narrowing his perceptions to a damaging extent. The experimental task may also decrease in importance in the face of other problems that are posed by the stress conditions. Although to the experimenter the performance of the task may be the central criterion of adaptation, to the subject it may be comparatively unimportant.

In any event, a central concern is the mechanism or mechanisms underlying impairment and improvement in functioning under stress. And since it is difficult, without further knowledge of the determining conditions, to predict which way, if at all, performance will be affected, inferences about psychological stress from changes in performance contain unresolved difficulties.

Some key theoretical issues in the field of psychological stress may be expressed by the questions: What are the antecedents of stress reactions? What processes of coping are generated and by what conditions are they produced? What observable consequences do each of the coping processes have? These issues are complex. Let us consider some of the main ones.

Threat, frustration, and conflict. The terminological confusion that exists in the area of threat, frustration, and conflict has already been touched upon. Theoretical solutions, of course, carry with them terminological conventions upon which there is not necessarily wide agreement (see Lazarus 1966). Still, we must seek some sort of clarity. The word that most clearly connotes the psychological aspects of stress is “threat.” The characteristics of threat must be defined and differentiated from other similar or overlapping concepts, such as frustration and conflict.

Threat refers to the anticipation of harm of some kind, an anticipation that is created by the presence of certain stimulus cues signifying to the individual that there is to be an experience of harm. This experience of harm may be called the “confrontation” (researchers into the psychological aspects of disaster call it the “impact”). Threat refers not to this confrontation but rather to the anticipation of it. The immediate stimulus configuration resulting in threat merely heralds the coming of harm. Threat is thus a purely psychological concept, an interpretation of a situation by the individual. Although the anticipated harm could be some physical injury, the meaning of the term “harm” is usually broadened to include damage to important goals and values.

Both frustration and conflict are concepts often confused with threat, even though they have specific meanings of their own. All three have been considered as antecedents of aggression, regression, anxiety, and defense. When these terms are used loosely, their distinctive features and their possibly different roles in behavior tend to be obscured.

Frustration is the actual blockage of some goal-oriented behavior. We speak of a motive‘s being frustrated or thwarted when a goal cannot be attained or when gratification is delayed. In such cases, frustration refers to a present or continuing confrontation with harm in the form of a goal that has already been blocked. The reasons for frustration are multiple; one of them is the presence of motivational conflict.

Conflict occurs when two goals are incompatible —that is, require contradictory behavior—or when the gratification of one goal frustrates the other. By definition, when conflict exists, then frustration is inevitable. Conflict is therefore one antecedent of frustration. If “conflict” is defined more broadly, to include the opposition between an external force or obstacle and the motive, then “conflict” and “frustration” tend to be interchangeable terms, although their emphases are slightly different. Conflict focuses on the motives involved, frustration on the blockage of motive gratification. From the point of view of psychological stress theory, it is the threatening and frustrating aspects of conflict that are important. [See Conflict, article on psychological aspects.]

Threat in its anticipatory sense is not routinely distinguished from frustration. Most experiments or naturalistic observations in the field of psychological stress have not clearly isolated these elements. For example, the classic observations of Grinker and Spiegel (1945) on war neuroses and Bettelheim (1960) on the concentration camp found that there is great frustration or confrontation with harm in the form of social degradation, hunger, physical injury, isolation from loved ones, and so forth. But there is also threat, in the sense that the present conditions signify continuing or future harm, perhaps even death. Grinker and Spiegel appear to emphasize the threat aspect of military combat. The emphasis on anticipation of harm is nowhere more clearly emphasized than in the literature on disaster (for example, Janis 1962). Psychologists and sociologists in their work on disaster distinguish a warning period in which the individual anticipates the impact of a disastrous storm or flood. Reactions that are observed include anxiety, defense mechanisms, disorganized thinking, and so on—in other words, the same consequences that are commonly attributed to frustration.

Failure to consider the separate aspects of threat and frustration is widespread in the experimental literature on aggression, where the emphasis is placed on frustration as the antecedent of aggression. The same trend has been followed by recent analytic writers on aggression, such as Berkowitz (1962). The threat and frustration components are never isolated in such research. Therefore, it is not clear to what extent anticipation or confrontation accounts for the observed stress reactions.

There are some observations in which threat alone has been isolated and in which the very reactions usually attributed to frustration have been observed. Some of the work on disaster mentioned above constitutes one example, especially where a warning period is distinguished before the calamity has actually happened. An experiment by Shannon and Isbell (1963) is another example. These authors exposed several groups of dental patients to varying procedures connected with the injection of an anesthetic, sometimes employing no anesthetic and sometimes merely going through all the motions of an injection short of actual needle insertion. Following their carefully designed procedures, they found that stress response consisting of an elevated level of hydrocortisone (an adrenal cortical hormone associated with stress) in the blood followed the anticipation of the injection and was as great as that found when the needle was actually inserted and the drug actually injected. In effect, it was not the actual physical pain, tissue damage, or drug effects that produced the stress reaction but merely the realization that an injection would be experienced. There appears to be a sound basis for viewing the various stress reactions as based on threat. There is no clear agreement among researchers about what aspects of the stimulus condition produce the stress reaction. Sometimes threat is emphasized and sometimes frustration. Often the distinction is simply overlooked. It is clearly an unresolved issue in stress research.

Threat and anxiety. The tendency to treat anxiety as the only intervening variable in psychological stress analysis poses some theoretical difficulty in which controversial issues reside. Conflict, or the frustration produced by conflict, is commonly said to result in anxiety, which in turn triggers some form of defense. This analysis is confusing for two reasons. First, it is often implied that the defense is activated by the pain or discomfort of anxiety. But if this is the case, why is the responsibility for defense placed exclusively on anxiety and not, for example, on anger or depression, which are also distressing affects? Actually, in the clinical literature the assumption that anger and depression may lead to defense is common, as when manic states are considered to be defenses against “underlying” depression or when positive feelings are treated as reaction formations against anger. But this view provides a plurality of intervening variables. Anxiety cannot then be considered to be the intervening variable promoting defenses.

The second problem with treating anxiety as the only intervening variable is that when such affective disturbances as anxiety are taken as the “cause” of defense, the actual cognitive processes producing it are underemphasized. If anxiety is the reaction to anticipated harm as heralded by stimulus cues, then it is not the pain or discomfort of the anxiety that generates the defense but rather the recognition by the individual that there is danger. Indeed, Freud, whose analyses of these problems have most influenced later researchers, shifted his views about anxiety during the course of his prolific career and finally regarded anxiety as the signal of danger. But to what psychological structure or agency is the signal useful? In Freud‘s analysis, anxiety signals the ego about the danger. But the main function of the ego is to distinguish safe from unsafe conditions. Why then should the structure which already has the function of interpreting reality need to be informed about what it already “knows” to be harmful? The role of anxiety, both as the intervening variable in psychological stress analysis and as an affective response, remains the subject of intense disagreement. The role of anxiety touches on the problem of consciousness or awareness, about which there is also continuous debate. [See Anxiety.]

Cognitive processes and threat. There is an increasing realization that cognitive processes are involved in threat and in the production of anxiety and other affects. Some of the difficulties inherent in the treatment of anxiety as the intervening variable in psychological stress can be resolved by regarding it entirely as a response to threat and by making threat itself the intervening variable. This has the virtue of emphasizing the cognitive activity preceding anxiety. Anxiety then becomes an affective response to the anticipation of harm (which is the definition of threat). Whether the response is anxiety, fear, anger, depression, guilt, or shame depends on the way the individual evaluates the situation and on the consequences of any form of adaptive response he might make.

Cognitive processes and emotion . The role of cognitive processes in emotion in general is becoming increasingly emphasized in present day psychological thought and research. An example is the major work of Arnold (1960), in which emotion is understood in terms of the individual‘s evaluation or appraisal of the personal significance of the stimulus. If the stimulus is appraised as beneficial, a positive emotion, such as joy or contentment, will ensue. If it is appraised as harmful, a negatively toned emotional state, such as fear or anger, will result. Emotion itself consists of an action tendency with respect to the stimulus, an action tendency that has motor and physiological correlates. In this way, Arnold links emotion to the cognitive process of appraisal. Appraisal means the evaluation of the significance of the cues at hand. If they are taken to signify the imminence of harm, threat and stress reactions are produced. [See Emotion.]

Experimental study. One important and widely cited piece of recent research (Schachter & Singer 1962) highlights the importance of cognitive processes in the production of different kinds of emotion. Some subjects were given epinephrine injections and others given a placebo under various experimental conditions. The epinephrine produced the expected sympathetic nervous system activation. By means of trained “stooges,” two different social atmospheres were created. In one, a euphoric condition was created by having the stooge act in an appropriate fashion. In the other, an anger condition was produced by having the stooge react with anger about the injection procedure, so that he gradually went into a rage. Based on behavioral ratings and self-report data, the findings clearly indicate that the quality of the emotion experienced by the experimental subject as a result of the physiological arousal was dependent on the nature of the social atmosphere and the cognitions created by this atmosphere. Anger occurred when the social situation stimulated anger, and euphoria occurred in the euphoric social situation. The social atmosphere thus yielded a conception that shaped the actual emotional effects of the epinephrine injection.

The experiment conducted by Schachter and Singer is important because it turns attention to the neglected cognitive determinants of emotion and provides a clear refutation of the widespread assumption that emotion can be conceptualized purely in terms of physiological arousal. This assumption has now been effectively challenged, emphasizing a theoretical issue of great importance. As Arnold (1960) has insisted, the quality of emotional states depends on appraisal of the personal significance of the situation. The argument can easily be extended to stress reactions that include negatively toned emotional states like fear and anger.

Relevant dimensions of cognitive appraisal . If the concept of appraisal in the production of threat is to have more than merely subjective referents, then we must be able to specify the necessary and sufficient conditions of threat and nonthreat appraisals. There is little systematic work along these lines. The factors determining appraisal are classifiable into those that reside in the external stimulus configuration and those that are within the psychological structure of the individual, as traits or dispositions. A few examples will be suggested.

Ratio of harm-producing to harm-combating aspects. Relevant to the stimulus configuration is something that might be referred to as the balance of power between the harm-producing stimulus and the counterharm resources of the individual. Threat is aroused when the former heavily outweighs the latter. If the individual believes that he can readily overcome or reverse the danger, threat is minimal or absent. Empirical examples can be found in which, for example, the casualty rates in military combat are positively correlated with incidence of psychological breakdown or where the experience and skill of the individual minimizes or reduces the threat that originally existed in his early states of contact with the dangerous conditions (Epstein 1962). Jam‘s (1958) and Mechanic (1962) have each emphasized this line of reasoning.

Imminence of harm. Another, less emphasized factor in the stimulus configuration is the imminence of the confrontation with harm. Threat is more intense when the harm is more imminent. For example, Epstein (1962) has evaluated approach and avoidance tendencies of parachute jumpers during the twenty-four-hour period preceding the jump, leading up to it, and culminating in the landing. As the time of final commitment to the jump approached, avoidance tendencies (evidence of threat) increased to a maximum, until they actually exceeded the approach (positive) tendencies.

Another example of the role of imminence of confrontation comes from Mechanic‘s study (1962) of the reactions of a group of graduate students facing a crucial examination. More students reported anxiety and more symptoms of anxiety were observed as the date of the examination grew nearer. Changes were also noted in the type of adaptive solutions displayed by the students as the deadline neared.

Another, more anecdotal example of the role of the imminence of confrontation with harm in determining the degree of threat may be found in people‘s reactions to the prospect of their own deaths. Even though the prospect itself may be exceedingly threatening, the fact that it may be regarded as long distant (not imminent) greatly reduces the intensity of the threat. Under conditions that make it appear imminent, threat is greatly intensified.

Ambiguity of cues. The role of ambiguity of the stimulus cues has been dealt with at some length by Janis (1962). As in projective stimuli, ambiguity encourages the operation of factors within the psychological structure of the individual. In Janis‘ terms, the new and ambiguous information will be assimilated to the previously existing psychological set or expectation of the person. If he has previously interpreted the situation as benign, an ambiguous cue will be interpreted in a way that is consistent with this idea; similarly, if he has previously interpreted the situation as dangerous, ambiguous information will become part of his fearful outlook and be assimilated to it.

Motives and beliefs. Concerning factors within the psychological structure, patterns of motivation and belief systems are fundamental to threat appraisal. Studies may be found (for example, Vogel et al. 1959) which demonstrate that threat is minimal when the stimulus conditions occur in the presence of a weak motive and greater when a powerful motive is engaged. In effect, what is threatening depends on the motive characteristics of the individual. In the absence of individually oriented assessments of motivation, researchers in the field of psychological stress have tended to emphasize shared or widespread sources of threat, sometimes recognizing that the conditions employed were not of equal threat value to all individuals studied. Sources of threat are universal or widespread because of shared cultural or experiential factors. Even such widespread threats as death are subject to motivational and cognitive factors as sources of individual differences. For example, recent researchers have noted wide variations in what it is about death that is actually feared, and there are great individual variations in conceptions of what will happen to the person after death.

Belief systems about the nature of one‘s transactions with the environment appear to play an interesting part in the appraisal of threat. We can regard the individual who is, for example, chronically anxious as believing that the environment is hostile or dangerous or that his own resources are too limited to cope with danger. Questionnaires about anxiety often contain items reflecting such beliefs. Observations by Persky and his associates (Persky et al. 1959) show that subjects with such beliefs (identified by measures of chronic anxiety) are more readily threatened by a strange experimental situation (as measured by the amount of increase of hydrocortjsone in the blood) than non-anxious subjects. Yet the latter react more to specific threats within the total experimental situation. The former subjects are threatened by any new situation, whereas the latter are comfortable in novel situations but are threatened by specifically harmful features of the situation. [See Attitudes; Thinking, article oncognitive organization and processes.]

Not everyone would agree with this particular interpretation of the effects of measured anxiety on threat appraisal in novel situations. For example, there are questions about the actual meaning of scales presumably measuring anxiety and about the conceptualization of the processes that underlie the reaction patterns just described. But regardless of theory and current difficulties concerning the assessment and labeling of personality variables, the facts appear to be that certain people are likely to appraise new situations as threatening and in fact give stress reactions almost chronically to many types of situations that do not especially disturb others. On the basis of personality measures like anxiety scales, it is possible to predict with some success the level of stress reaction the individual will show in social contexts to which he has not yet become accustomed.

Coping processes and reactions to threat. The patterns of reaction that define the presence of threat are variable and complex. They are often not in agreement with each other, as, for example, when the individual denies any affective distress but gives evidence of it in behavioral or physiological changes. The same condition that produces stress reaction in one individual results in no evidence of threat in another. Furthermore, one individual will react with anger and attack, while another will show fear and flee. Some of these variations represent individual differences in the psychodynamics of threat production. Other disagreements arise from difficulties of measurement.

The concept of reaction . A major source of variation in reaction has to do with the kinds of coping processes that are generated by threat. In introducing the concept of coping process, the term “reaction” to threat requires some additional comment. Unfortunately, “reaction” usually connotes a passive and automatic state not necessarily involving active efforts to master or cope with a danger. This passive implication is not at all intended here, nor is it implied in any of the theory and research on coping processes. It is precisely because threat must be coped with and the individual must employ his experience and resources to meet it that the prediction of stress reactions is so complex. Different individuals bring different resources to the situation, and processes of coping are required that sensitively reflect the options available to the individual and the consequences of any action taken. In a valuable study of psychological stress in graduate students brought about by doctoral examinations, Mechanic (1962) examines in some detail the strategies of adaptation that are selected. The focus in this work is on how the student deals or copes with threat. But an additional principle that makes the study of coping processes valuable is that the stress reaction as observed in behavior depends on the kind of coping process the individual adopts. For example, attack as a means of coping with threat will appear behaviorally, and perhaps even physiologically, to be different from flight or avoidance. Thus, to understand the observed reaction we must correctly identify the active choices that the individual makes in coping with threat.

Evaluation of coping processes . There is a strong tendency in the literature to distinguish between various types of coping processes—for example, those in which the individual attempts directly to alter the threatening conditions themselves and those in which he attempts to change only his appraisal of them so that he need not feel threatened. The former are often referred to as adaptive behavior or as coping devices, whereas the latter are usually called defenses. It is generally assumed that coping devices are healthier, since they offer some means of actually mastering or changing the situation. By using defenses, the individual may become more comfortable but remain vulnerable to external danger. A persistent issue in the discussion of this problem relates to what is healthy and what is not. Some theorists point out that defensive processes may be adaptive, at least in preventing psychological disorganization where no adaptive solution is really possible. Others regard coping processes as healthy and defenses as pathological. The problem of criteria for healthy or effective processes of coping as opposed to pathological ones remains an important and controversial issue within psychological stress theory and research. There is little agreement among the experts about this issue.

Aggression—cognitive aspects of coping. If we are to understand the observable reaction pattern to stress it is important to consider the coping processes that produce it. Perhaps more research has been performed on aggression than on any other threat reaction, making it a fine illustration of the type of issue that arises in this work.

The trend toward postulating and investigating cognitive processes as antecedents of threat may be found in the research on aggression. The earlier conception of aggression as an instinctual drive has fallen out of favor even among orthodox psychoanalysts because of the circularity of this approach. In its place is the view that aggression is a response to frustration. Aggression or attack may be regarded as a form of coping with the conceived source of the harm. But attack is one of many coping reactions, and it is necessary to specify the conditions that determine attack as the coping process rather than avoidance or defense mechanism.

The role of cognitive processes in the production of aggression as a means of coping with threat is illustrated in some of the findings of research reviewed by Berkowitz (1962). For example, when the antecedent frustrating condition created by the experimenter is not arbitrary or capricious and appears to the subject to occur through no fault of the frustrating agent, aggression will not occur as readily as when the frustration appears arbitrary. Either it is inhibited or it is weaker, an issue on which much research centers (see Berkowitz 1962). Furthermore, if the social sanctions against attack are weakened, aggression will be more apt to occur. And if there are strong internal moral sanctions against aggression, direct, behaviorally expressed aggression is also less likely, presumably because it is inhibited from expression. Finally, if the frustrating agent is powerful or prestigious and capable of harmful retaliation against any attack, direct aggression is also less likely on the part of the threatened or frustrated individual. These findings support the concept of an evaluating individual who perceives the social forces of a situation and his own place within it and whose behavior is shaped by this appraisal. [See Aggression.]

Defense mechanisms as a form of coping. The concept of defense mechanism has been widely accepted and applied in psychological stress theory and in clinical practice. Fundamentally, defense is regarded as consisting of a variety of psychological processes that have in common the distortion of reality as a means of reducing threat (or anxiety, in the typical formulation). Defense is contrasted with more active forms of coping in which the actual conditions of threat are altered. For example, when the individual who is threatened with failure attempts to learn what he must know to pass an examination, he is attempting to influence the actual forces involved in the threat. But when he distorts the actual realities, by convincing himself that he cannot fail, he is engaging in defense. [See Defense mechanisms.]

There has been comparatively little progress in the theory of defense since its basic outlines were expounded in Freudian theory. Theories of defense are largely descriptive; that is, they specify the types of strategies but do not specify the processes and conditions that determine them. Or if they do, they are not stated in ways that lend themselves to clear empirical testing. Thus, much controversy centers on the details of the concept of defense. For example, there is little agreement about patterns of defenses within the same individual or about which ones underlie each type of psychopathology. Unresolved is the question of whether a given defense is a general trait of the personality that can be activated by any threat or whether it is linked to a specific kind of threat. Psychologists who attempt to measure “defense preferences” assume the former position, whereas Freudian theory appears to take the latter position. In the latter viewpoint each defense is related to a particular stage of psychosexual development (and its particular instinctual drive—for example, oral, anal aggressive, or Oedipal) and to a particular set of symptoms of psychopathology. But this conceptual neatness is not readily supported by the observable patterns with which the clinician deals. It remains an assumption that is often challenged. Also unresolved is the matter of distinguishing such defense behaviors as those associated with denial from instances where threat is absent. In both cases the individual says, “I am not angry or distressed,” but in one case this report reflects a defense against threat, while in the other the statement correctly describes an internal state. The observable signs that permit the identification of these inferred processes are not well established.

Contributing stimulus conditions . Some interesting efforts have been made to pin down the stimulus conditions under which one or another defense will occur.

Projection. A study by Bramel (1962) is illustrative. He found that projection as a defense does not occur as readily when the person who might be the object of the projection is negatively evaluated by the threatened individual. Ratings of desirable and undesirable characteristics of experimental partners were made before the experiment proper began by a group of male subjects. Then while a fake physiological indicator, supposedly indicating their sexual arousal, was attached to them, the subjects observed photographs of men. By manipulating the indicator, the experimenter in effect was able to convincingly suggest that the subject had homosexual impulses. The indicator was made to rise sharply when the subject looked at pictures of the most provocative males. Following this threatening information, the subject was asked to evaluate homosexual tendencies in the original partner, a task which permitted the projection or attribution of the undesirable impulse to another individual like himself. Control subjects not having the threatening experience showed no tendency to project the homosexuality on the other person. Where the partner had been evaluated in positive terms, threatened subjects attributed homosexuality to him with significantly larger frequency. Bramel concludes that projection, as a defense against threat, requires a positively regarded object and will not be useful in reducing threat if the object is seen as an undesirable character. Moreover, Bramel argues, projection occurs in his study because the threatening information was so convincing that it could not readily be denied.

Denial. Clinical research also points to situational determinants of denial defenses. Research with the patient who is dying of cancer shows him to be under great social pressure to accept the myth that he will recover. Relatives and friends and other visitors to the patient are extremely uneasy about facing openly with the patient the dreadful outlook. In their hospital visits they encourage the denial of the truth. The patient, fearful of losing contact with his loved ones, who appear to withdraw uneasily when the terminal nature of the disease is faced, is pressured into a denial process both by his own wish and by the social pressure, although often he gives evidence that the defense is not fully successful and that below the surface of awareness he recognizes the truth. The work cited above points up more recent efforts to pin down some of the external situational factors that determine which defense is selected as a means of coping with threat. There is as yet only a trickle of data on this very important problem.

Personality factors . Personality factors also determine the choice of defenses. Defenses may be treated as personality dispositions, traits which operate to some extent in spite of situational variations. Studies have demonstrated that such dispositions operate to determine the success of a defense-oriented communication in reducing threat. For example, Lazarus and Alfert (1964) utilized a disturbing motion picture depicting a primitive ritual of adolescence called “subincision,” in which a series of genital operations with a flint knife is shown. If nothing is said about the film events, autonomic and subjective evidence of disturbance rises dramatically during the operation scenes and falls during benign scenes. If the threatening events of the film are pointed up in an orientation passage or sound track, the level of stress reaction is even greater. If the pain or other dangers of the operation are denied convincingly in an orientation passage prior to the film presentation, or if an attitude of intellectualized detachment is presented, the over-all level of stress reaction is markedly lowered. But the effectiveness of these defensive orientation passages in reducing the stress reaction depends on measured defensive dispositions. Subjects typically disposed to denial as a preferred defense get more relief from the denial orientation than from the intellectualized detachment. They seem better able to adopt the attitude presented. Similarly, subjects inclined to deal with threat by intellectualization gain most from the intellectualization passage and little from the denial statements. The utilization of defensive orientations to reduce threat appears to depend, in part, on defensive dispositions within the personality.

Comparatively little research has been done on the conditions that determine particular strategies of coping with threat. Naturalistic observation in the field provides abundant hypotheses about these conditions. If we are to extend our knowledge beyond the point of mere ability to describe the psychological strategies of defense, it will be necessary to employ effective laboratory analogues of these processes to test the often contradictory assumptions about these forms of coping with threat.

Methodological issues. One difficult methodological problem concerns the setting in which stress reactions and their causes occur.

Naturalistic observations . A considerable literature exists in which naturalistic observations have been made of people in real life stress situations. While there are many examples, the work of Grinker and Spiegel (1945) on battle, that of Janis (1958) on the threat of surgery, and that of Bettelheim (1960) on the concentration camp are classic ones. Although these studies offer rich hypotheses about the sources of stress and the mechanisms of stress production and reduction, it is difficult to isolate systematically the variables that are operating, since the situations studied are enormously complex, the measurement of reactions comparatively informal, and the assessment of causes often retrospective.

Laboratory studies . In contrast are the laboratory studies of stress in which control and measurement of the variables are comparatively precise. However, levels of stress are usually mild or moderate, since ethical and practical considerations limit the extent and the range of situations that are possible with human subjects. Moreover, the very fact that a subject conceives of the situation as experimental raises the question whether laboratory analogues are good models of real life situations. What is gained in control may be lost in artificiality of the setting. The issue is basic to all experimentation and generates protagonists for either the naturalistic or the laboratory orientation. The difficulties of each cannot be wholly eliminated. Therefore, the fullest theoretical analysis of psychological stress will ultimately derive from the wise integration of both kinds of data.

Measurement . It is difficult to discuss the field of psychological stress without touching on the measurement of such key variables as threat. The experimenter must be able to infer degree of threat and the nature of the coping process on the basis of the pattern of reaction that he observes. As previously noted, the response variables in psychological stress analysis include different levels—for example, subjectively reported affect, observed motor-behavioral adjustments, and physiological reactions that may include a dozen or so different autonomic nervous system response variables and a number of adrenal hormones found in the blood or urine. Investigators have differed widely over the kinds of response variables they have emphasized and over the number they have observed.

Problem of agreement among measurements. One fundamental problem in measurement has been the low order of correlation that is found between different measures presumably indicating stress reaction. Even within a response class (for example, among different autonomic nervous system measures, such as heart rate, electrical conductivity of the skin, respiration, blood pressure, and so forth), the correlation is low to moderate at best. Sometimes this poor correlation may be attributed to methodological errors or technological limitations. For example, it has been shown that particular procedures for measuring heart-rate variations will increase the agreement between heart rate and the level of skin conductance above what is usually obtained, and Lazarus and his associates (Lazarus et al. 1963) have demonstrated that intraindividual approaches yield higher agreement between measures than interindividual approaches do. Intraindividual analysis has made it possible to show considerable agreement between autonomic measurement and self-report ratings of disturbance. But even if all the methodological and technical difficulties of measurement were overcome, it is doubtful that very high correlations would ever be found between the different stress-response indicators. And if the measures employed to index stress reaction do not agree substantially, theoretical as well as methodological questions may be raised about the justification of treating any one of them as a stress-response measure.

There are excellent theoretical reasons why disagreement exists between stress indicators. These reasons can be summarized by the general statement that each indicator, while indeed dependent on threat appraisal, is also dependent on different specific psychological and physiological intervening processes. In any study, some of these processes are not relevant to the investigator‘s concern and constitute a kind of nuisance variance in the system, while other processes convey important information about psychological stress mechanisms.

Response specificity. An example of variance that can be a nuisance in some cases is based on response specificity in psychophysiology and psychosomatic medicine (Engel 1960). This concept was introduced partly to explain the absence of correlation between autonomic nervous system indicators. Each indicator involves some particular tissue system—for example, the sweat glands, the heart muscle, the blood vessels, and so on. It has been shown that certain individuals may be consistently more reactive in one measure—say, blood pressure—than in another. In effect, subjects are constitutionally different, and if the investigator is measuring only one indicator he may overestimate reactivity in one subject and underestimate it in another, depending on whether he has chosen the sensitive or insensitive measure. Naturally, then, two different indicators may not agree very well with each other. From the point of view of measuring stress reaction, this constitutional variation is a nuisance that interferes with accurate inferences. From the point of view of psychosomatic disease, however, it is of the utmost importance, since one individual may develop the disorder of hypertension rather than some other disease just because of this constitutional quirk that makes him respond to threat with heightened blood pressure. [See Psychosomatic Illness.]

Stimulus specificity. The concept of stimulus specificity, in contrast to response specificity, suggests that the pattern of autonomic reaction will be different for different sources of threat or in different kinds of emotional reactions (Lacey et al. 1963). Recent evidence, for example, suggests that the physiological patterns of fear and anger may be different. Thus, from the point of view of measurement of stress reaction, stimulus specificity requires that we employ the appropriate indicators in order to identify the particular pattern that is generated by the specific threat; otherwise, it might be missed or the degree of threat incorrectly estimated. Moreover, if our interest lies in identifying the process of coping with threat, the precise nature of the response is important since it will tell us something about the coping process. Yet both stimulus specificity and response specificity, however they are ultimately defined and understood, occur at the expense of agreement among autonomic indicators of threat. The more response variation depends on the stimulus or the physical constitution of the individual, the less agreement can we expect to find among indicators.

Individual differences and environment. On the psychological side, the pattern of reaction of the individual across different types and levels of response reveals something about the nature of his transactions with the environment, his particular psychodynamics. And different kinds of measures reveal different features of these transactions. For example, if the individual wishes to create the impression that he is brave, he may refuse to admit to fear in military combat even though he is very frightened. Or, in other contexts, he may deny anger. In such a situation, autonomic and adrenal evidence of stress reaction will probably be found. The pattern of evidence may appear different if the reaction is fear than if the reaction is anger. Here we have lawful disagreement between two legitimate response indicators of stress reaction, reported disturbances of affect and physiological arousal. Sometimes psychologists have relied on expressive indicators of emotion to correct for the lack of candidness of the individual. But even expressive indicators such as gestures, facial expressions, and body postures may be employed by the individual to conceal how he feels or to create a social impression he thinks is desirable, since the individual also knows that his styles and expressive movements contain socially relevant information.

The point is that no single class of indicators, behavioral or physiological, is free from the influence of other variables that have nothing to do with threat. For example, adrenal cortical hormonal substances are increased in the blood as a result of psychologically based threats as well as physical assaults. Thus, walking up a hill on the golf course in exuberance will result in some of the same kinds of physiological arousal as sitting quietly and experiencing anxiety. Similarly, autonomic nervous system measures are also subject to such irrelevant influence. Temperature and humidity changes, and indeed even air pollution, will have substantial effects. In other words, the indicators we use physiologically to measure stress reaction also tend to vary with anything that makes the individual more aroused or activated.

The dilemma posed here is that the measurement of stress relevant processes is exceedingly complex, and no simple, single class of measurement device can solve the problem adequately. The clinician knows this when he carefully observes many features of a reaction: subjective report, gestures, the goal directedness of acts, the consistency over time of what the individual reports, and evident signs of physiological reactions, such as flushing or pallor. The pattern of these reactions provides the basis of inferences about internal psychological activity.

It has been suggested that the shortcomings of one measuring device should be compensated for by the simultaneous use of others. Then, only where there is agreement between a number of indicators can we afford to make an inference about anxiety (or threat or defense). But we can not expect the various indicators to be always in high agreement, especially if we recognize that each approach reveals something different about the individual‘s psychodynamics. It is only through these very disagreements that we recognize efforts on the part of individuals to present themselves socially in a certain way or to utilize defenses or other forms of coping. When irrelevant artifacts in our measurement techniques have been ruled out, then the apparent contradictions between stress-response indicators are no longer necessarily contradictory but serve as crucial sources of inference about the underlying processes relevant to psychological stress.

Richard S. Lazarus

[See also Anxiety; Fatigue. Other relevant material may be found in Aggression; Defense Mechanisms; Motivation; Psychology, article onconstitutional psychology; Space, outer, article onsocial and psychological aspects.]

BIBLIOGRAPHY

Arnold, Magda B. 1960 Emotion and Personality, 2 vols. New York: Columbia Univ. Press. → Volume 1: Psychological Aspects. Volume 2: Neurological and Physiological Aspects.

Berkowitz, Leonard 1962 Aggression: A Social Psychological Analysis. New York: McGraw-Hill.

Bettelheim, Bruno 1960 The Informed Heart: Autonomy in a Mass Age. Glencoe, 111.: Free Press.

Bramel, Dana 1962 A Dissonance Theory Approach to Defensive Projection. Journal of Abnormal and Social Psychology 64:121-129.

Easterbrook, J. A. 1959 The Effect of Emotion on Cue Utilization and the Organization of Behavior. Psychological Review 66:183-201.

Engel, Bernard T. 1960 Stimulus-Response and Individual-response Specificity. AMA Archives of General Psychiatry 2:305-313.

Epstein, Seymour 1962 The Measurement of Drive and Conflict in Humans: Theory and Experiment. Volume 10, pages 127-209 in Nebraska Symposium on Motivation. Edited by Marshall R. Jones. Lincoln: Univ. of Nebraska Press.

Farser, I. E. 1955 The Role of Motivation in Verbal Learning and Performance. Psychological Bulletin 52:311-327.

Grinker, Roy R.; and Spiegel, John P. 1945 Men Under Stress. Philadelphia: Blakiston. → A paperback edition was published in 1963 by McGraw-Hill.

Janis, Irving L. 1958 Psychological Stress: Psychoanalytic and Behavioral Studies of Surgical Patients. New York: Wiley.

Janis, Irving L. 1962 Psychological Effects of Warnings. Pages 55-92 in George W. Baker and Dwight W. Chapman (editors), Man and Society in Disaster. New York: Basic Books.

Korchin, Sheldon J. 1964 Anxiety and Cognition. Pages 58-78 in Martin Scheerer Memorial Meetings on Cognitive Psychology, University of Kansas, 1962, Cognition: Theory, Research, Promise. New York: Harper.

Lacey, John I. et al. 1963 The Visceral Level: Situ-ational Determinants and Behavioral Correlates of Autonomic Response Patterns. Pages 161-196 in Symposium on Expression of the Emotions in Man, New York, 1960, Expression of the Emotions in Man. Edited by Peter H. Knapp. New York: International Universities Press.

Lazarus, Richard S. 1966 Psychological Stress and the Coping Process. New York: McGraw-Hill.

Lazarus, Richard S.; and Alfert, Elizabeth 1964 The Short Circuiting of Threat by Experimentally Altering Cognitive Appraisal. Journal of Abnormal and Social Psychology 69:195-205.

Lazarus, Richard S.; Deese, J.; and Osler, S. F. 1952 The Effects of Psychological Stress Upon Performance. Psychological Bulletin 49:293-317.

Lazarus, Richard S.; Speisman, J. C.; and Nordkoff, A. M. 1963 The Relationship Between Autonomic Indicators of Psychological Stress: Heart Rate and Skin Conductance. Psychosomatic Medicine 25:19-30.

Mechanic, David 1962 Students Under Stress: A Study in the Social Psychology of Adaptation. New York: Free Press.

Opton, E. M. Jr.; Alfert, Elizabeth; and Lazarus, Richard S. 1967 Personality Determinants of Psycho-physiological Response to Stress: A Theoretical Analysis and an Experiment. Unpublished manuscript.

Persky, Harold et al. 1959 Effect of Two Psychological Stresses on Adrenocortical Function. Archives of Neurology and Psychiatry 81:219-226.

Sarason, Irwin G. 1960 Empirical Findings and Theoretical Problems in the Use of Anxiety Scales. Psychological Bulletin 57:403-415.

Schachter, Stanley; and Singer, Jerome E. 1962 Cognitive, Social, and Physiological Determinants of Emotional State. Psychological Review 69:379-399.

Selye, Hans 1956 The Stress of Life. New York: McGraw-Hill.

Shannon, Ira L.; and Isbell, G. M. 1963 Stress in Dental Patients: Effect of Local Anesthetic Procedures. Technical Report No. SAM-TDR-63-29. Brooks Air Force Base, Texas: USAF School of Aerospace Medicine.

Smelser, Neil J. (1962) 1963 Theory of Collective Behavior. London: Routledge; New York: Free Press.

Spielberger, Charles D. (editor) 1966 Anxiety and Behavior. New York: Academic Press. → See especially “The Study of Psychological Stress: A Summary of Theoretical Formulations and Experimental Findings,” by R. S. Lazarus and E. M. Opton, Jr.

Vogel, William; Raymond, Susan; and Lazarus, Richard S. 1959 Intrinsic Motivation and Psychological Stress. Journal of Abnormal and Social Psychology 58:225-233.

Withey, Stephen B. 1962 Reaction to Uncertain Threat. Pages 93-123 in George W. Baker and Dwight W. Chapman (editors), Man and Society in Disaster. New York: Basic Books.

Stress

Definitions

The neurobiology of stress

Physical effects of chronic stress

Stress and mental disorders

Causes of stress

Risk factors

Coping with stress

Resources

Definitions

Stress is a term that refers to the sum of the physical, mental, and emotional strains or tensions on a person. Feelings of stress in humans result from interactions between persons and their environment that are perceived as straining or exceeding their adaptive capacities and threatening their well-being. The element of perception indicates that human stress responses reflect differences in personality and physiology as well as differences in physical strength or health.

A stressor is defined as a stimulus or event that provokes a stress response in an organism. Stressors can be categorized as acute or chronic, and as external or internal to the organism. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) defines a psychosocial stressor as “any life event or life change that may be associated temporally (and perhaps causally) with the onset, occurrence, or exacerbation [worsening] of a mental disorder.”

Stress affects the lives of most adults in developed countries in many ways. It is a major factor in rising health care costs; one public health expert maintains that 90% of all diseases and disorders in the United States are stress-related. Stress plays a part in many social problems such as child and elder abuse , workplace violence, juvenile crime, suicide , substance addiction , “road rage,” and the general decline of courtesy and good manners. Stress also affects the productivity of businesses and industries.

In a recent survey, two-thirds of Americans reported that they are likely to seek help for stress. Work appears to play a high-profile role in the stress burden among Americans. A total of 45% of workers gave job insecurity as a factor in work-related stress levels in a 2004 survey, and in the same survey, 61% of workers cited heavy workloads as a source of stress. A total of 52% said that work was a greater source of stress than home life, and 54% were concerned about stress-related health problems. Even economically, the connection between work and stress has costs: one in four workers has taken a “mental health day” from work because of stress. Money is also a factor in individual stress: 73% of Americans report that financial worry is the top factor in their level of stress.

The neurobiology of stress

One way to understand stress as a contemporary health problem is to look at the human stress response as a biologically conditioned set of reactions that was a necessary adaptation at earlier points in human evolution, but is less adaptive under the circumstances of modern life. Hans Selye (1907–1982), a Canadian researcher, was a pioneer in studying stress. Selye defined stress, in essence, as the rate of wear and tear on the body. He observed that an increasing number of people, particularly in the developed countries, die of so-called diseases of civilization, or degenerative diseases, which are primarily caused by stress. Selye also observed that stress in humans depends partly on people’s evaluation of a situation and their emotional reaction to it; thus, an experience that one person finds stimulating and exciting—for example, bungee jumping—would produce harmful stress in another.

The stress response

In humans, the biochemical response to acute stress is known as the “fight-or-flight” reaction. It begins with the activation of a section of the brain called the hypothalamic-pituitary-adrenal system, or HPA. This system first activates the release of steroid hormones, which are also known as glucocorticoids. These hormones include cortisol, the primary stress hormone in humans.

The HPA system then releases a set of neurotrans-mitters known as catecholamines, which include dopamine , norepinephrine, and epinephrine (also known as adrenaline ). Catecholamines have three important effects:

• They activate the amygdala, an almond-shaped structure in the limbic system that triggers an emotional response of fear.
• They signal the hippocampus, another part of the limbic system, to store the emotional experience in long-term memory.
• They suppress activity in parts of the brain associated with short-term memory, concentration, and rational thinking. This suppression allows a human to react quickly to a stressful situation, but it also lowers ability to deal with complex social or intellectual tasks that may be part of the situation.

In reaction to stress, heart rate and blood pressure rise, and the person breathes more rapidly, which allows the lungs to take in more oxygen. Blood flow to the muscles, lungs, and brain may increase by 300-400%. The spleen releases more blood cells into the circulation, which increases the blood’s ability to transport oxygen. The immune system redirects white blood cells to the skin, bone marrow, and lymph nodes; these are areas where injury or infection is most likely.

At the same time, nonessential body systems shut down. The skin becomes cool and sweaty as blood is drawn away from it toward the heart and muscles. The mouth becomes dry, and the digestive system slows down.

The relaxation response

After the crisis passes, the levels of stress hormones drop and the body’s various organ systems return to normal. This return is called the relaxation response. Some people are more vulnerable to stress than others because their hormone levels do not return to normal after a stressful event. An absent or incomplete relaxation response is most likely to occur in professional athletes and in people with a history of depression .

Physical effects of chronic stress

In chronic stress, the organ systems of the body do not have the opportunity to return fully to normal levels. Different organs become under- or overacti-vated on a long-term basis. In time, these abnormal levels of activity can damage an organ or organ system.

Cardiovascular system

Stress has a number of negative effects on the heart and circulatory system. Acute, sudden stress increases heart rate, but also causes the arteries to narrow, which may block the flow of blood to the heart. The emotional effects of stress can alter the rhythm of the heart. In addition, stress triggers an inflammatory response in the blood vessels that can ultimately result in injury to the lining of the arteries. Markers of inflammation, linked to the development of cardiovascular disease, are also markers of the “acute phase response” to stress. Stress also can cause a change in cholesterol levels, with an increase in fats in the blood that can eventually lead to clogged arteries, which can lead to heart attack or stroke .

Gastrointestinal system

The effects of chronic stress on the gastrointestinal system include diarrhea, constipation, bloating, and irritable bowel syndrome. Although stress does not cause ulcers, which arise from an infection with Helicobacter pylori bacteria, it can exacerbate them. Stress also can influence inflammatory bowel disease, stimulating colon spasms and possibly interacting with the immune system in producing flareups.

Stress is the cause of abnormal weight loss in some people and of weight gain in others, largely from stress-related eating. It is thought that stress related to the physical and emotional changes of puberty is a major factor in the development of eating disorders.

Reproductive system

Stress affects sexual desire in both men and women and can cause impotence in men. It appears to worsen the symptoms of premenstrual syndrome (PMS) in women. Stress affects fertility because the high levels of cortisol in the blood can affect the hypothalamus, which produces hormones related to reproduction. Very high levels of cortisol can cause amenorrhea, or cessation of menstrual periods.

In pregnancy, stress has been strongly associated with miscarriage during the earliest weeks of gestation, and cortisol, the “stress hormone,” is associated with this risk; in a recent study, 90% of women with high cortisol levels experienced a miscarriage in the first three weeks of pregnancy, compared to 33 percent of women with normal cortisol levels. High stress levels of the mother during pregnancy are also related to higher rates of premature births and babies of lower than average birth weight; both are risk factors for infant mortality. In addition, stress during pregnancy is also associated with negative effects that persist after birth.

Musculoskeletal system

Stress intensifies the chronic pain of arthritis and other joint disorders. It also produces tension-type headaches, caused by the tightening of the muscles in the neck and scalp. Research indicates that people who have frequent tension headaches have a biological predisposition for converting emotional stress into muscle contraction.

Brain

The physical effects of stress hormones on the brain include interference with memory and learning. Acute stress interferes with short-term memory, although this effect goes away after the stress is resolved. People who are under severe stress become unable to concentrate; they may become physically inefficient, clumsy, and accident-prone. In children, however, the brain’s biochemical responses to stress clearly hamper the ability to learn.

Chronic stress appears to be a more important factor than aging in the loss of memory in older adults. Older people with low levels of stress hormones perform as well as younger people in tests of cognitive (knowledge-related) skills, but those with high levels of stress hormones test between 20% and 50% lower than the younger test subjects.

Immune system

Chronic stress affects the human immune system and increases a person’s risk of getting an infectious illness. Several research studies have shown that people under chronic stress have lower-than-normal white blood cell counts and are more vulnerable to colds and influenza. Men with HIV infection and high stress levels progress more rapidly to AIDS than infected men with lower stress levels.

Stress and mental disorders

DSM-IV-TR specifies two major categories of mental disorders directly related to stres: the post-traumatic syndromes and adjustment disorders . Stress is, however, also closely associated with depression, and can worsen the symptoms of most other disorders.

Post-traumatic disorders

Post-traumatic stress disorder (PTSD) and acute stress disorder (ASD) are defined by their temporal connection to a traumatic event in the individual’s life. The post-traumatic disorders are characterized by a cluster of anxiety and dissociative symptoms, and by their interference with the patient’s normal level of functioning. Magnetic resonance imaging (MRI) studies have shown that the high levels of sustained stress in some PTSD patients cause demonstrable damage to the hippocampus. Excessive amounts of stress hormones in brain tissue cause the nerve cells, or neurons, in parts of the hippocampus to wither and eventually die. One group of Vietnam veterans with PTSD had lost as much as 8% of the tissue in the hippocampus.

Substance abuse disorders

Stress is related to substance abuse disorders in that chronic stress frequently leads people to self-medicate with drugs of abuse or alcohol. Substance abuse disorders are associated with a specific type of strategy for dealing with stress called emotion-focused coping. Emotion-focused coping strategies concentrate on regulating painful emotions related to stress, as distinct from problem-focused coping strategies, which involve efforts to change or eliminate the impact of a stressful event. Persons who handle stress from a problem-oriented perspective are less likely to turn to mood-altering substances when they are under stress.

Adjustment disorders

DSM-IV-TR defines adjustment disorders as psychological responses to stressors that are excessive given the nature of the stressor; or result in impairment of the person’s academic, occupational, or social functioning. The most important difference between the post-traumatic disorders and adjustment disorders is that most people would not necessarily regard those stressors involved in the latter disorder as traumatic. Adjustment disorder appear to be most common following natural disasters, divorce, birth of a child, and retirement from work.

Causes of stress

The causes of stress may include any event or situation that a person considers a threat to his or her resources or coping strategies. A certain amount of stress is a normal part of life; it represents a person’s response to inevitable changes in his or her physical or social environment. Moreover, positive as well as negative events can generate stress. Graduating from college, for example, is accompanied by stress related to the challenge of finding employment or possible geographical relocation and the stress of saying good-bye to friends and family, as well as feelings of positive accomplishment. Some researchers refer to stress associated with positive events as eustress.

Acute stress is defined as a reaction to something perceived as an immediate threat. Acute stress reactions can occur to a falsely perceived danger as well as to a genuine threat; they can also occur in response to memories. For example, a war veteran who hears a car backfire may drop to the ground because the noise triggers vivid memories, called flashbacks, of combat experience. Common acute stressors include loud, sudden noises; being in a crowded space such as an elevator; being cut off in heavy traffic; and dangerous weather. Chronic stress is a reaction to a situation that is stressful but ongoing, such as financial insecurity or caring for an elderly parent. Modern life is stressful because changes in various areas of life have increased the number of acute and chronic stressors in most people’s lives at the same time that they have weakened certain buffers or protections against stress.

Social changes

Social changes that have increased the stress level of modern life include increased population mobility and the sprawling size of modern cities. It is not unusual for adults to live hundreds of miles away from parents and siblings; and it is hard to make and keep friendships when people move every few years. In most large cities, many people live in apartment buildings where they do not know their neighbors. Social isolation and loneliness can produce chronic stress. A five-year study done in Norway found that social support networks made a significant difference in lowering the impact of both acute and chronic stress on mental health.

Social scientists have observed that the increased isolation of married couples from extended families and friendship networks increases strains on the marriage. The rising divorce rate in the United States has been attributed in part to the loss of social supports that once helped to keep married couples together. The experience of divorce then adds to the stress level on the former spouses and the children, if any. A long-term study at the University of Pittsburgh has found that divorce is associated with a higher rate of premature death in men.

Economic changes

The rapid pace of change in manufacturing and other businesses means that few people will work at the same job for their entire career. In addition, corporate mergers and downsizing have weakened job security, thus producing chronic anxiety about unemployment in the minds of many employees. Many people work two jobs in order to make ends meet; and even those who work only one job often have to commute long distances by car or train to their workplace. In many large American cities, traffic jams, high gasoline prices, and other problems related to commuting are a major factor in job-related stress. Another stress factor is sleep deprivation. In a recent poll by the National Sleep Foundation, 52% of respondents fell into the “not-so-good” sleeper categories. Fatigue due to sleep deprivation causes additional stress.

Last, economic trends have produced a “winner-take-all” economy in which the gap between the well-off and the average family is constantly widening. Socioeconomic status (SES) affects health in a number of ways. Persons of higher SES can afford better health care, are less likely to suffer from exposure to environmental toxins, and generally lead healthier lifestyles. In addition, chronic stress associated with low SES appears to increase morbidity and mortality among persons in these income groups.

Technological changes

Technology has proved to be a source of stress as well as a solution to some kinds of stress. Machines that help workers to be more productive also make their jobs more complicated and raise the level of demands on them. An office clerk in 2007 can produce many more letters per day than an office clerk of 1952, but is often expected to produce more elaborate, professional-looking documents as well as a higher number of them.

One specific technological development that has been singled out as a major stressor in modern life is the evolution of news reporting. For most of human history, people had to wait several days or even weeks to hear about the outcome of an election, a battle, or some other important event. Moreover, they usually heard only the news that affected their region or their country. Today, however, news is reported as soon as it happens, it is broadcast 24 hours a day, it is accessible throughout the day via the Internet, and it covers events from around the world. This “communications overload,” as it has been termed, is a source of genuine stress to many people, particularly when the emphasis is on upsetting or frightening events. It is not surprising that a common recommendation for lowering one’s stress level is to cut down on watching television news programs. A team of physicians conducted telephone interviews following the terrorist attacks against the U.S. of September 11, 2001, to assess stress reactions in the general American population. The team found that the single most important factor was not geographical location relative to the attacks or educational level, but the amount of time spent watching televised reports of the attacks. The interviewers discovered that 49% of the adults had watched at least eight hours of television on September 11, and also that “extensive television viewing was associated with a substantial stress reaction.”

Environmental changes

One significant source of stress in modern life is the cumulative effect of various toxic waste products on the environment. Studies of the aftermath of such environmental disasters as the Three Mile Island and Chernobyl nuclear plant accidents found that not only evacuees and people living in the contaminated area had high levels of emotional distress, but also cleanup workers and people living in nearby noncontaminated areas. In the case of Chernobyl, Russian physicians have reported a psychoneurological syndrome with several unexplained symptoms, including fatigue, impaired memory, muscle or joint pain, and sleep disturbances. The syndrome appears to be due to chronic emotional stress rather than radiation exposure.

Changes in beliefs and attitudes

Changes in beliefs that influence stress levels include the contemporary emphasis on individualism and a corresponding change in attitudes toward trauma. A number of observers have remarked that Western culture has moved away from its traditional high valuation of the family and community toward an increased focus on the individual. Some have called this trend the “Me First!” society—it emphasizes personal rights and entitlements rather than duties and responsibilities to others. It has, in the view of some physicians, encouraged people to dwell on trauma and its effects on them as individuals rather than to live up to more traditional ideals of composure and resilience in the face of distress.

Risk factors

Research indicates that some groups of people have a higher risk of stress-related illnesses and disorders:

• Children have very little control over their environments. In addition, they are often unable to communicate their feelings accurately.
• In elderly adults, aging appears to affect the body’s response to stress, so that the relaxation response following a stressful event is slower and less complete. In addition, the elderly are often affected by such major stressors as health problems, the death of a spouse or close friends, and financial worries.
• Caregivers of mentally or physically disabled family members.
• Women in general.
• People with less education.
• People who belong to racial or ethnic groups that suffer discrimination.
• People who live in cities.
• People who are anger-prone. Chronic anger is associated with narrowing of the arteries, a factor in heart disease.
• People who lack family or friends.
• People who are biologically predisposed to an inadequate relaxation response.

Coping with stress

Coping is defined as a person’s patterns of response to stress. Many clinicians think that differences in attitudes toward and approaches to stressful events are the single most important factor in assessing a person’s vulnerability to stress-related illnesses. A person’s ability to cope with stress depends in part on his or her interpretation of the event. One person may regard a stressful event as a challenge that can be surmounted while another views it as a problem with no solution. The person’s resources, previous physical and psychological health, and previous life experience affect interpretation of the event. Someone who has had good experiences of overcoming hardships is more likely to develop a positive interpretation of stressful events than someone who has been repeatedly beaten down by abuse and later traumas.

Coping styles

The ways in which people cope with stress can be categorized according to two different sets of distinctions. One is the distinction between emotion-focused and problem-focused styles of coping, which was described earlier in connection with substance abuse. Problem-focused coping is believed to lower the impact of stress on health; people who use problem-focused coping have fewer illnesses, are less likely to become emotionally exhausted, and report higher levels of satisfaction in their work and feelings of personal accomplishment. Emotion-focused coping, on the other hand, is associated with higher levels of interpersonal problems, depression, and social isolation. Although some studies reported that men are more likely to use problem-focused coping and women to use emotion-focused coping, other research done in the last decade has found no significant gender differences in coping styles.

The second set of categories distinguishes between control-related and escape-related coping styles. Control-related coping styles include direct action, behavior that can be done alone; help-seeking, behavior that involves social support; and positive thinking, a cognitive style that involves giving oneself pep talks. Escape-related coping styles include avoidance/resignation, as in distancing oneself from the stressful event, and alcohol use. There appears to be no relationship between gender and a preference for control-related or escape-related coping.

Stress management

Stress management refers to a set of programs or techniques intended to help people deal more effectively with stress. Many of these programs are oriented toward job- or workplace-related stress in that burnout is a frequent result of long-term occupational stress, which has been divided into three categories: (1) Problems with the person–environment fit (e.g., a mismatch between personal skills and those required for the job; (2) problems with the balance between the demands of the job and the person’s control over decisionmaking; and (3) problems with imbalances between the effort required to do the job and rewards associated with that effort.

Most stress-management programs ask participants to analyze or identify the specific aspects of their job that they find stressful, and then plan a course of positive action to minimize the stress. In general, the severity of job-related stress appears to be related to two factors: the magnitude of the demands being made on the worker, and the degree of control that she or he

KEY TERMS

Adjustment disorder —A disorder defined by the development of significant emotional or behavioral symptoms in response to a stressful event or series of events. Symptoms may include depressed mood, anxiety, and impairment of social and occupational functioning.

Adrenaline —Another name for epinephrine, the hormone released by the adrenal glands in response to stress. It is the principal blood-pressure raising hormone and a bronchial and intestinal smooth muscles relaxant.

Allostasis —The process of an organism’s adaptation to acute stress.

Amygdala —An almond-shaped brain structure in the limbic system that is activated in acute stress situations to trigger the emotion of fear.

Burnout —An emotional condition that interferes with job performance, marked by fatigue, loss of interest, or frustration; usually regarded as the result of prolonged stress.

Catecholamine —A group of neurotransmitters synthesized from the amino acid tyrosine and released by the hypothalamic-pituitary-adrenal system in the brain in response to acute stress. The catecholamines include dopamine, serotonin, norepinephrine, and epinephrine.

Coping —In psychology, a term that refers to a person’s patterns of response to stress.

Cortisol —A steroid hormone released by the cortex (outer portion) of the adrenal gland when a person is under stress.

Dissociation —A reaction to trauma in which the mind splits off certain aspects of the traumatic event from conscious awareness. Dissociation can affect the patient’s memory, sense of reality, and sense of identity.

Eustress —A term that is sometimes used to refer to positive stress.

Flashback —The re-emergence of a traumatic memory as a vivid recollection of sounds, images, and sensations associated with the trauma. The person having the flashback typically feels as if he or she is reliving the event.

Hippocampus —A part of the brain that is involved in memory formation and learning. The hippocampus is shaped like a curved ridge and belongs to an organ system called the limbic system.

Homeostasis —The tendency of the physiological system in humans and other mammals to maintain its internal stability by means of a coordinated response to any stimulus that disturbs its normal condition.

Limbic system —A group of structures in the brain that includes the amygdala, hippocampus, olfactory bulbs, and hypothalamus. The limbic system is associated with homeostasis and the regulation and arousal of emotions.

Relaxation response —The body’s deactivation of stress responses and return of stress hormone levels to normal after a threat has passed.

Stress management —A set of techniques and programs intended to help people deal more effectively with stress in their lives by analyzing the specific stressors and taking positive actions to minimize their effects. Most stress management programs deal with job stress and workplace issues.

Stressor —A stimulus or event that provokes a stress response in an organism. Stressors can be categorized as acute or chronic, and as external or internal to the organism.

has in dealing with the demands. The workers who are most vulnerable to stress-related heart disease are those who are subjected to high demands but have little control over the way they do their job. In many cases, stress management recommendations include giving an employee more decision-making power.

Treatments for stress

Some recommended guidelines for treating stress include trying one or more of the following: relaxation techniques (e.g., meditation ), exercise, behavioral training (e.g., anger management training), cognitive therapy, and changes in work. There are a number of allopathic and alternative/complementary treatments that are effective in relieving the symptoms of stress-related disorders:

• Medications may include drugs to control anxiety and depression as well as drugs that treat such physical symptoms of stress as indigestion or high blood pressure.
• Psychotherapy, including insight-oriented and cognitive/behavioral approaches, is effective in helping people understand how they learned to overreact to stressors, and in helping them reframe their perceptions and interpretations of stressful events. Anger management techniques are recommended for people who have stress-related symptoms due to chronic anger.
• Relaxation techniques, anxiety reduction techniques, breathing exercises, yoga, and other physical exercise programs that improve the body’s relaxation response.
• Therapeutic massage, hydrotherapy, and bodywork are forms of treatment that are particularly helpful for people who tend to carry stress in their muscles and joints.
• Aromatherapy, pet therapy, humor therapy, music therapy, and other approaches that emphasize sensory pleasure are suggested for severely stressed people who lose their capacity to enjoy life; sensory-based therapies can counteract this tendency.
• Naturopathic recommendations regarding diet, exercise, and adequate sleep, and the holistic approach of naturopathic medicine can help persons with stress-related disorders to recognize and activate the body’s own capacities for self-healing.

See alsoCreative therapies; Diets; Nutrition and mental health.

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders.4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

Gleick, James. Faster: The Acceleration of Just About Everything.New York: Pantheon Books, 1999.

Herman, Judith, MD. Trauma and Recovery.2nd ed., revised. New York: Basic Books, 1997.

“Psychosomatic Medicine (Biopsychosocial Medicine).” Section 15, Chapter 185 in The Merck Manual of Diagnosis and Therapy,edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2000.

Selye, Hans. The Stress of Life.Revised edition. New York: McGraw-Hill Book Company, Inc., 1976.

PERIODICALS

Adler, N. E., and K. Newman. “Socioeconomic Disparities in Health: Pathways and Policies. Inequality in Education, Income, and Occupation Exacerbates the Gaps Between the Health ‘Haves’ and ‘Have-Nots.”’ Health Affairs (Millwood)21 (March-April 2002): 60-76.

Black, Paul H., and Garbutt, Lisa D. “Stress, inflammation, and cardiovascular disease.”Journal of Psychosomatic Research52(2002): 1-23.

Evans, O., and A. Steptoe. “The Contribution of Gender-Role Orientation, Work Factors and Home Stressors to Psychological Well-Being and Sickness Absence in Male- and Female-Dominated Occupational Groups.” Social Science in Medicine 54 (February 2002): 481–492.

Levenstein, Susan. “Stress and Peptic Ulcer: Life Beyond Helicobacter.” British Medical Journal 316 (February 1998): 538–541.

Lombroso, Paul J. “Stress and Brain Development, Part 1.” Journal of the American Academy of Child and Adolescent Psychiatry 37 (December 1998).

Lucini, Daniela, Riva, Silvano, Pizzinelli, Paolo, and Pagani, Massimo. “Stress management at the worksite: reversal of symptoms profile and cardiovascular dysregulation.” Hypertension 49(2007): 291–297.

McEwen, Bruce. “Stress and Brain Development, Part 2.” Journal of the American Academy of Child and Adolescent Psychiatry 38 (January 1999).

Matthews, K. A., and B. B. Gump. “Chronic Work Stress and Marital Dissolution Increase Risk of Posttrial Mortality in Men from the Multiple Risk Factor Intervention Trial.” Archives of Internal Medicine 162 (February 2002): 309–315.

Mayer, Merry. “Breaking Point (Job Stress and Problem Employees).” HR Magazine 46 (October 2001): 79–85.

Nepomnaschy, Pablo A., Welch, Kathleen B., McConnell, Daniel S., Low, Bobbi S., Strassmann, Beverly I., and England, Barry G. “Cortisol levels and very early pregnancy loss in humans.” Proceedings of the National Academy of Science 103 (2006): 3938–3942.

Olstad, R., H. Sexton, and A. J. Sogaard. “The Finnmark Study: A Prospective Population Study of the Social Support Buffer Hypothesis, Specific Stressors and Mental Distress.” Social Psychiatry and Psychiatric Epidemiology 36 (December 2001): 582–589.

Pastel, R. H. “Radiophobia: Long-Term Psychological Consequences of Chernobyl.” Military Medicine 167 (February 2002): 134–136.

Schuster, Mark A., Bradley D. Stein, Lisa H. Jaycox, and others. “A National Survey of Stress Reactions After the September 11, 2001, Terrorist Attacks.” New England Journal of Medicine 345 (November 15, 2001): 1507–1512.

Summerfield, Derek. “The Invention of Post-Traumatic Stress Disorder and the Social Usefulness of a Psychiatric Category.” British Medical Journal 322 (January 13, 2001): 95–98.

van der Kolk, Bessel. “The Body Keeps the Score: Memory and the Evolving Psychobiology of PTSD.” Harvard Review of Psychiatry 1 (1994): 253–265.

Wadhwa, Pathik D. “Psychoneuroendocrine processes in human pregnancy influence fetal development and health.” Psychoneuroendocrinology 30(2005): 724–743.

ORGANIZATIONS

The American Institute of Stress. 124 Park Avenue, Yonkers, NY 10703. (914) 963-1200. Fax: (914) 965-6267. www.stress.org

Anxiety Disorders Association of America. 11900 Parklawn Drive, Suite 100, Rockville, MD 20852-2624. (301) 231-9350. www.adaa.org

Stress and Anxiety Research Society (STAR). www.star-society.org

American Psychiatric Association, 1400 K Street NW, Washington D.C. 20005. http://www.psych.org

National Center for PTSD, 1116D V.A. Medical Center, 215 N. Main Street, White River Junction, VT 05009-0001. (802)296-5132. http://www.ncptsd.org

WEBSITES

American Psychological Association. “How does stress affect your body?” (interactive) http://helping.apa.org/articles/article.php?id=141 (accessed 01/21/07).

Centers for Disease Control. “Stress at work.” http://www.cdc.gov/niosh/topics/stress/(accessed 01/21/07).

National Library of Medicine. “Stress.” http://www.nlm.nih.gov/medlineplus/stress.html

National Library of Medicine. “Stress and anxiety.” http://www.nlm.nih.gov/medlineplus/ency/article/003211.htm

“Stress-related conditions and other mental disorders.” http://www.guidelines.gov/summary/

National Sleep Foundation. “2005 Results of the Sleep in America Poll.” http://www.sleepfoundation.org/_content/hottopics/Sleep_Segments.pdf

Rebecca Frey, Ph.D.

Stress

Stress research includes attention to events or conditions that may cause harm and to the responses aroused by those stressful events or conditions. These outcomes include felt distress, disrupted interaction, and poorer health. The overall stress process includes both stressful agents and stress outcomes (see Pearlin et al. 1981). This process also includes two other major sets of variables: social factors that influence exposure to stressful conditions, and individual and group resources that shape efforts to cope with stressors.

Although early stress research focused on unpleasant physical stressors (Selye 1982), social scientists studying families have been particularly interested in social stressors—events or conditions that are linked to individuals' and families' social characteristics, positions, and roles.

The concept of social stress calls attention to both environmental/social demands and individual/family capacities or resources; stress occurs when there is a discrepancy between these capacities and demands. Such stressors can come from external demands on families and family members, or they can arise within family roles themselves. Theoretically, a discrepancy can be in either direction: demands could be greater than a person's capacities, or demands could be far below individual capacities. Thus, restricted opportunities can be at least as stressful as high demands: Carol Aneshensel (1999; see also Wheaton 1999) calls attention to stressors that occur when aspects of the social environment obstruct an individual's ability to attain sought-after ends.

One early and influential approach to studying social stressors focused on change per se as stressful. Thomas A. Holmes and Richard H. Rahe (1967) developed a checklist of stressful life events aimed at capturing the set of events that had happened to an individual. These checklist approaches to the measurement of social stress were based on two key assumptions. First, they assumed that one could calculate a standard estimate of the amount of change demanded by a specific event, such as divorce or the birth of a child, and that this amount would be generally the same for all who experienced that event. Second, they assumed that one could capture the effects of the accumulation of several events in a short period of time by summing the amount of change implied by each, and that this total amount of change was the critical dimension linked to stress outcomes.

Subsequent research, however, has cast doubt on each of these assumptions. Change per se does not seem to be the key dimension producing negative outcomes: changes that are undesired, involuntary, unexpected, and involve role losses generally have more negative effects than other changes. Nor is it the case that the same event has uniform effects on different people. Consistent with the concept of stress as a discrepancy between demands and capacities, much depends on the resources and coping repertoires that individuals and families possess.

In addition, the impact of transitions and eventful changes depends in part on the circumstances prevailing prior to a specific life event. A notable example is marital termination: although the end of a marriage is generally viewed as a stressful event, termination of a conflict-filled or unsatisfying relationship may actually improve well-being. And because spouses may differ in how satisfied they are, this example also suggests that the same family event will not necessarily affect all members of a family in the same way. In an influential analysis, Blair Wheaton (1990) has shown that in the case of role exits, including retirement, widowhood, divorce, and a child's move away from home, the more stressful prior conditions in that role, the less the impact on mental health. Similarly, Susan Jekielek (1998) finds that children's response to parental divorce is less adverse when there has been more marital conflict.

Effects of specific life events also depend in part on the subsequent level of chronic problems. It is largely because major life events typically result in an enduring alteration in social circumstances, thereby increasing chronic problems, that they affect individual and family outcomes.

Chronic problems in any given role can also lead to other stressors, in a process that Leonard Pearlin and his colleagues describe as stress proliferation—the tendency of stressors to beget other stressors (Pearlin, Aneshensel, and LeBlanc 1997). They illustrate this process in a study of informal caregivers to people with acquired immunodeficiency syndrome (AIDS). As the illness progresses, the difficulties faced in the role of caregiver expand, straining one's capacities to manage those demands. Moreover, these strains affect the caregiver's ability to enjoy the opportunities, and manage the stressors, embedded in other roles such as work roles and social and leisure activities. Once these are affected, the altered conditions in these other roles can have an additional, independent effect on the caregiver's health and well-being.

Thus, the concept of social stressors reaches beyond the notion of discrete life events to include chronic or persisting circumstances, such as low income, unpleasant working conditions, role strains, and conflicts among multiple social roles, as well as the resources that individuals and families are able to bring to bear in their efforts to deal with their circumstances. Because both those circumstances and resources are likely to be linked to social position—as indicated by one's race, gender, marital status, and economic position—this broad definition of social stress brings stress research closer to traditional sociological topics such as social stratification and race and gender discrimination. It offers a more comprehensive way of thinking about the way that social circumstances, including normatively structured family and occupational social roles, shape individual opportunities, individual distress, and family well-being.

Research analyzing the connection between social contexts and stress outcomes for individuals and families has examined several key links. First, research has examined how stressors originating outside the family can affect individual family members' emotional well-being (see, for example, Windell and Dumenci 1999). Second, researchers have investigated how each individual's emotional well-being in turn affects family interaction; these studies find that individuals who are struggling with emotional turmoil or depression are less available for satisfying interaction and more prone to become aggressive and argumentative (Elder 1974). Third, studies also examine how and whether one family member's emotional state can be transmitted to other family members (Larson and Almeida 1999); initial results from these studies suggest that fathers' negative emotions aroused in the workplace "spill over" and affect both spouses and children, but mothers' work-linked emotions are less apt to adversely affect other family members. In turn, of course, negative emotions aroused by difficult family conditions can spill over and affect workplace interaction and performance.

Exposure and Responses to Stressors

As family stress researchers study the resourceful ways in which individuals and families resist stressors, they have also called attention to the ways that social and economic factors shape both their exposure to stressors and their abilities to respond.

In considering the relationship between stressful circumstances on the one hand and family members' individual well-being and overall family functioning on the other, research has tended to focus on two main questions: How can variations in exposure to social stressors explain variations in individual and family outcomes? How, in a group of individuals or families who have been exposed to the same stressor, can variations in individual and family capacities, resources, and coping efforts explain variations in outcomes?Exposure to social stressors. An example of the former is the investigation conducted by Pearlin and his colleagues (1981) into the effect of occupational disruptions on emotional distress. They compared those who had faced recent disruptions with respondents who had not, with statistical controls for other variables known to affect both the likelihood of disruption and the levels of emotional distress, and traced the effects of disruption through diminished self-esteem and compromised sense of mastery to increased distress. Similarly, early family stress research examined exposure to stressors linked to social organization and societal crises, such as widespread male unemployment and extended separations brought on by World War II (see Hill 1949).

These early studies focused on men's unemployment as a social stressor for themselves and their families. As women's employment increased, studies began to examine whether women's holding multiple social roles—both family roles as spouse and mother and work roles as employee—operated as a social stressor, with adverse consequences for themselves and other family members, particularly children. This research has generally been inconclusive: simple cross-sectional contrasts between employed and not-employed mothers have found, if anything, an average benefit of employment for women and little significant differences in their children's outcomes. Ingrid Waldron and her colleagues (1998) provide an example of this line of research, as well as an overview of theoretical arguments regarding how combinations of marriage, mothering, and employment may affect women's health. They find little evidence that combining employment and mothering has adverse effects on physical health. They suggest that marriage and employment each provide similar resources to women, namely income and social supports, and that they can substitute for one another in having a beneficial impact on health. Conversely, these findings suggest that the absence of both marriage and employment will be associated with more negative outcomes.

In extensions of this line of research, researchers have argued that the effects of having a particular role or role combination are not uniform, but depend on the role conditions one encounters. For example, research in this tradition focused on employment emphasizes that for men as well as for women, employment in occupations that are free from close supervision and provide opportunities for substantively complex and self-directed work will yield benefits, whereas employment in dull, repetitive, and closely supervised work will not (Kohn and Schooler 1983; Menaghan 1991). Similarly, all marriages are not equal in their costs and benefits, with high-conflict, hostile, or distant relationships more distressing than their counterparts. In support of these arguments, Elizabeth Menaghan and her colleagues (1997) show that the quality of mothers' employment, as well as the quality of their marital relationships, affect mother-child interaction and adolescent children's academic and behavior outcomes.

Variations in response to stressors as a function of resources. An example of the latter question is Glen Elder's (1974) study of families who faced serious economic decline during the Great Depression. Elder investigated whether couples with more cohesive marital bonds at a prior point were better able to respond to the economic difficulties they faced. Here, the cohesion of marital bonds is conceptualized as a family-level resource that accounted for a difference in outcomes among couples all facing the same economic stressor. In general, family stress researchers have conceptualized stressful outcomes as a function of three major factors: the stressor, family resources, and appraisal or interpretation (Hill 1949). Extending this model, Yoav Lavee and his colleagues emphasized potential changes over time in each of these factors (see Lavee, McCubbin, and Patterson 1985). Work by Pauline Boss (1999) calls attention to the critical role of appraisal in influencing family members' responses to ambiguous or incomplete losses, including family members who are missing, suffering from dementia, or geographically or emotionally distant.

These same factors are also central to studies of stress at the individual level. Pearlin and his colleagues (1981) stress how material, social, and psychosocial resources, including optimistic appraisals, help to account for variations in the individual distress aroused by stressful circumstances in normative adult roles such as marriage, employment, and parenting. In both literatures, economic resources, social supports from others, coping strategies, and individual levels of self-esteem and mastery are viewed as central resources that can reduce the negative impact of social stressors (Mirowsky and Ross 1986; Turner 1999).

One of the pathways by which social stressors may create adverse impacts is by reducing resources themselves. For example, a period of involuntary unemployment may have a less disastrous impact on families with greater savings. If the period of unemployment is prolonged, however, or if unemployment recurs, families may literally "spend down" their resources. This is probably easiest to measure in terms of tangible resources like savings, but the general argument holds as well for more subtle resources like a sense of mastery over one's circumstances. At any single time point, having more optimistic and internal attitudes may help one to manage potential stressors. But over time, exposure to stressors may cumulatively reduce those feelings of control. Thus, current levels of resources may partially reflect the cumulative history of encounters with social stressors.

Who is exposed to social stressors? To fully understand the processes by which stressors affect families, we also need to consider how social stressors are distributed in populations. Exposure to difficult life events or constraining social circumstances is not a random process, and it is important to view variations in exposure to stressors as a phenomenon that itself needs to be explained. For example, Jay Turner and colleagues (1995) study what they call the epidemiology of social stress. They find that the distribution of exposure to social stressors varies significantly by age, gender, marital status, and occupational status, and this distribution parallels the distribution of depressive symptoms and major depressive disorder across the same factors. Catherine Ross and Marieke Van Willigen (1997) also point to educational attainment as a crucial resource that shapes subsequent exposure to more or less stressful circumstances.

Turner and Lloyd (1999) extend this analysis, and find that exposure to social stressors, as well as levels of personal resources and social supports, can explain, on the one hand, observed links between age, gender, marital status, and socioeconomic status, and mental health outcomes on the other. In particular, the linkage between lower socioeconomic status and higher depressive symptoms is completely accounted for by the greater exposure to stressors and fewer resources and social supports of those with lower educations, occupations, and incomes.

Effects of Economic Stressors on Marital Behaviors

Social stress research has repeatedly identified low income and income loss as a major social stressor (see for example, Elder 1974; McLloyd 1990). Given the importance of family income, and its links to both employment and family composition, researchers in the United States have sought to understand how economic circumstances and family formation and stability are linked. As Scott South and Kim Lloyd (1992) have documented, higher rates of male nonemployment have been shown to be associated with reduced marriage rates and higher rates of births to unmarried women for both African-American and white population groups. Women's economic resources also matter: Diane McLaughlin and Daniel Lichter (1999) comment that marriage can provide a route out of poverty for some, but find that poor women, especially those who do not hold jobs, are less likely to marry than are more advantaged women.

Marriages stressed by economic uncertainties have also been more likely to be disrupted. When financial pressures are high, husbands and wives treat each other more negatively, quarrel more, and feel increasingly distant; thoughts of divorce become more common. And as wives' greater employment and earnings prompt them to question disproportionate female responsibility for housework and childcare, conflict between partners is apt to increase. Donald Hernandez (1993) has found that married-couple families below the poverty level are more likely to disrupt their marriages than are couples who have greater economic resources. Among married couples, husbands' nonemployment increases the likelihood of marital disruption (South and Spitze 1986). This occurs in part because men react to employment loss and associated economic hardship with anger, irritability, and withdrawal from interaction (Conger et al. 1990).

Lower likelihood of marital formation and higher rates of marital disruption clearly affect children's life chances as well. In the absence of marriage or after its end, U.S. fathers have been relatively unlikely to share income or time with their biological children, and single-mother families are most vulnerable to economic problems.

Societal Differences, Demographic Factors, and Family Stressors

Much social stress research has focused on differences in exposure and response to social stressors within a single nation, typically the United States. We can gain additional insights if we broaden our perspective to consider differences between nations around the globe. One example is the link between single mothering and low income just noted. In the United States, children living with never-married and formerly married parents, particularly mothers, are disproportionately likely to have low incomes. But in a comparative perspective, it becomes clear that this is not an inevitable consequence of single-mothering: the proportion in poverty varies dramatically across the developed countries, with U.S. rates much higher than in such countries as France or the Netherlands (see Lichter 1997). Lynne Casper and colleagues' (1994) examination of poverty among men and women across Western industrialized countries suggests that much of the explanation lies in differing national policies regarding income transfers and income floors for all citizens, as well as differing supports for employment. Thus, how employment affects families, and how family composition affects family income, varies across nations.

An international perspective also suggests other demographic factors that figure importantly into the kinds of social stressors that families encounter. For example, both within the United States and across the globe, race and ethnic groups vary in their social advantage/disadvantage, exposure to social stressors, and access to resources. These studies suggest that when economic problems become pervasive in a community, overall community levels of family violence and child abuse rise. To the extent that discriminatory labor-market practices compromise minority members' access to income, job security, and occupational quality, racially segregated communities will lack the resources families need to resist stress, and the families living with them may be exposed to greater social stressors as well (see, for example, McLloyd 1990).

As nations and regions become increasingly interconnected, migration across communities, states, and national borders presents an increasingly common social stressor for individuals and families. Min Zhou (1997) summarizes the family and intergenerational stressors that immigrants to the United States face, as family ties are stretched across national borders, and suggests that the success of various family adaptations strategies varies depending on the socioeconomic and ethnic composition of the communities into which they move. Samuel Noh and William Avison (1996) study the experiences of Korean immigrants to Canada, and link increases in depression over time to more undesirable life events, more chronic stressors, and less mastery and sense of support.

Migration may be permanent or temporary, and may involve whole families or individual members. The consequences of migration are likely to vary depending on the circumstances one is leaving behind, the extent of family resources that can be retained, and the conditions faced in one's new environment. Much migration is intentional, as individuals and families seek to improve their circumstances. But war, ethnic violence, crop failures and economic conditions also combine to create huge flows of political and economic refugees; these streams are apt to have fewer resources and greater difficulties.

Changing mortality patterns across populations and across the world also suggest new sources of social stress for families, particularly in the direction and duration of caregiving across generations. In the developed world, increasing life spans may present increased demands for caregiving by adult family members to their elders. In sharp contrast, in many areas of Africa and Asia, increases in sexually transmitted diseases, particularly AIDS-related diseases, have resulted in declining average life expectancies and the deaths of parents in early adulthood. These new mortality patterns create a generation of orphans and present increased demands for caregiving by elder family members and others.

Finally, studies of stress in families, and gender differences in average levels of well-being, call attention to differences in stress processes within families. Societies differ significantly in the extent to which male dominance and female subordination are accepted as part of the normative order. To the extent that male and female family members have strikingly different rights, freedoms, and responsibilities, it is reasonable to expect that they will be exposed to differing stressors, have differing access to social resources, and be differently affected by stressors. Thus, the study of stress in families, both within and across nations, must encompass both individual and family stressors and individual and family outcomes, without assuming that stressors affect male and female family members, or members of different societies, equally.

Conclusion

The study of social stressors affecting families draws attention to the linkages between social factors such as race, gender, education, occupation, and income, and how they shape both exposure to stressors and the possession of resources with which to deal with them. We have noted that greater levels of resources can keep potential social stressors from exerting adverse effects, but over time resources themselves can be whittled away by chronic or recurring exposure to social stressors. Despite much popular concern about role conflicts, particularly between work and family roles for women, studies suggest that more and less stressful conditions within roles may be more consequential than the simple presence or absence of a particular social role. This review of social stress research draws heavily on research conducted in the United States, but it suggests that the stress paradigm can provide a conceptual lens through which one can begin to explore variations in stressful exposure and outcomes across nations as well.

See also:Acquired Immunodeficiency Syndrome (AIDS); Boundary Ambiguity; Caregiving: Informal; Chronic Illness; Conflict: Family Relationships; Conflict: Marital Relationships; Conflict: Parent-Child Relationships; Death and Dying; Depression: Adults; Depression: Children and Adolescents; Disabilities; Divorce: Effects on Children; Divorce: Effects on Couples; Divorce: Effects on Parents; Elder Abuse; Family Development Theory; Family Roles; Family Strengths; Fatherhood; Gender; Health and Families; Marital Quality; Migration; Motherhood; Poverty; Power: Marital Relationships; Resource Management; Retirement; Single-Parent Families; Social Networks; Spouse Abuse; Theoretical Explanations; Transition to Parenthood; Unemployment; War/Political Violence; Widowhood; Work and Family

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ELIZABETH G. MENAGHAN

Stress

Definitions

Stress is a term that refers to the sum of the physical, mental, and emotional strains or tensions on a person. Feelings of stress in humans result from interactions between persons and their environment that are perceived as straining or exceeding their adaptive capacities and threatening their well-being. The element of perception indicates that human stress responses reflect differences in personality as well as differences in physical strength or health.

A stressor is defined as a stimulus or event that provokes a stress response in an organism. Stressors can be categorized as acute or chronic, and as external or internal to the organism. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR ) defines a psychosocial stressor as "any life event or life change that may be associated temporally (and perhaps causally) with the onset, occurrence, or exacerbation [worsening] of a mental disorder."

Stress affects the lives of most adults in developed countries in many ways. It is a major factor in rising health care costs; one public health expert maintains that 90% of all diseases and disorders in the United States are stress-related. Stress plays a part in many social problems such as child and elder abuse , workplace violence, juvenile crime, suicide , substance addiction , "road rage," and the general decline of courtesy and good manners. Stress also affects the productivity of businesses and industries. One nationwide survey found that 53% of American workers name their job as the single greatest source of stress in their lives. Furthermore, the overall cost of medical care, time lost from work, and workplace accidents in the United States comes to over $150 million per year.

The neurobiology of stress

One way to understand stress as a contemporary health problem is to look at the human stress response as a biologically conditioned set of reactions that was a necessary adaptation at earlier points in human evolution, but is less adaptive under the circumstances of modern life. Hans Selye (1907-1982), a Canadian researcher, was a pioneer in studying stress. Selye defined stress, in essence, as the rate of wear and tear on the body. He observed that an increasing number of people, particularly in the developed countries, die of so-called diseases of civilization, or degenerative diseases, which are primarily caused by stress. Selye also observed that stress in humans depends partly on people's evaluation of a situation and their emotional reaction to it; thus, an experience that one person finds stimulating and exciting—for example, bungee jumping—would produce harmful stress in another.

The stress response

In humans, the biochemical response to acute stress is known as the "fight-or-flight" reaction. It begins with the activation of a section of the brain called the hypothalamic-pituitary-adrenal system, or HPA. This system first activates the release of steroid hormones, which are also known as glucocorticoids. These hormones include cortisol, the primary stress hormone in humans.

The HPA system then releases a set of neurotransmitters known as catecholamines, which include dopamine, norepinephrine, and epinephrine (also known as adrenaline). Catecholamines have three important effects:

• They activate the amygdala, an almond-shaped structure in the limbic system that triggers an emotional response of fear.
• They signal the hippocampus, another part of the limbic system, to store the emotional experience in longterm memory.
• They suppress activity in parts of the brain associated with short-term memory, concentration, and rational thinking. This suppression allows a human to react quickly to a stressful situation, but it also lowers ability to deal with complex social or intellectual tasks that may be part of the situation.

In reaction to stress, heart rate and blood pressure rise, and the person breathes more rapidly, which allows the lungs to take in more oxygen. Blood flow to the muscles, lungs, and brain may increase by 300–400%. The spleen releases more blood cells into the circulation, which increases the blood's ability to transport oxygen. The immune system redirects white blood cells to the skin, bone marrow, and lymph nodes; these are areas where injury or infection is most likely.

At the same time, nonessential body systems shut down. The skin becomes cool and sweaty as blood is drawn away from it toward the heart and muscles. The mouth becomes dry, and the digestive system slows down.

The relaxation response

After the crisis passes, the levels of stress hormones drop and the body's various organ systems return to normal. This return is called the relaxation response. Some people are more vulnerable to stress than others because their hormone levels do not return to normal after a stressful event. An absent or incomplete relaxation response is most likely to occur in professional athletes and in people with a history of depression.

Physical effects of chronic stress

In chronic stress, the organ systems of the body do not have the opportunity to return fully to normal levels. Different organs become under- or overactivated on a long-term basis. In time, these abnormal levels of activity can damage an organ or organ system.

Cardiovascular system

Stress has a number of negative effects on the heart and circulatory system. Sudden stress increases heart rate, but also causes the arteries to narrow, which may block the flow of blood to the heart. The emotional effects of stress can alter the rhythm of the heart. In addition, stress causes the release of extra clotting factors into the blood, which increases the risk of a clot forming and blocking an artery. Stress also triggers the release of fat into the bloodstream, which temporarily raises blood cholesterol levels. Lastly, it is thought that people who regularly have sudden increases in blood pressure due to mental stress may over time suffer injuries to the inner lining of their blood vessels.

Gastrointestinal system

The effects of chronic stress on the gastrointestinal system include diarrhea, constipation, bloating, and irritable bowel syndrome. Although stress is not the direct cause of either peptic ulcers or inflammatory bowel disease, it may predispose people to develop ulcers and worsen flareups of inflammatory bowel disease.

Stress is the cause of abnormal weight loss in some people and of weight gain in others, largely from stress-related eating. It is thought that stress related to the physical and emotional changes of puberty is a major factor in the development of eating disorders.

Reproductive system

Stress affects sexual desire in both men and women and can cause impotence in men. It appears to worsen the symptoms of premenstrual syndrome (PMS) in women. Stress affects fertility, in that high levels of cortisol in the blood can affect the hypothalamus, which produces hormones related to reproduction. Very high levels of cortisol can cause amenorrhea, or cessation of menstrual periods.

Stress during pregnancy is associated with a 50% higher risk of miscarriage. High stress levels on the mother during pregnancy are also related to higher rates of premature births and babies of lower than average birth weight; both are risk factors for infant mortality.

Musculoskeletal system

Stress intensifies the chronic pain of arthritis and other joint disorders. It also produces tension-type headaches, caused by the tightening of the muscles in the neck and scalp. Research indicates that people who have frequent tension headaches have a biological predisposition for converting emotional stress into muscle contraction.

Brain

The physical effects of stress hormones on the brain include interference with memory and learning. Acute stress interferes with short-term memory, although this effect goes away after the stress is resolved. People who are under severe stress become unable to concentrate; they may become physically inefficient, clumsy, and accident-prone. In children, however, the brain's biochemical responses to stress clearly hamper the ability to learn.

Chronic stress appears to be a more important factor than aging in the loss of memory in older adults. Older people with low levels of stress hormones perform as well as younger people in tests of cognitive (knowledgerelated) skills, but those with high levels of stress hormones test between 20% and 50% lower than the younger test subjects.

Immune system

Chronic stress affects the human immune system and increases a person's risk of getting an infectious illness. Several research studies have shown that people under chronic stress have lower than normal white blood cell counts and are more vulnerable to colds and influenza. Men with HIV infection and high stress levels progress more rapidly to AIDS than infected men with lower stress levels.

Stress and mental disorders

DSM-IV-TR specifies two major categories of mental disorders directly related to stress—the post-traumatic syndromes and adjustment disorders. Stress is, however, also closely associated with depression, and can worsen the symptoms of most other disorders.

Post-traumatic disorders

Post-traumatic stress disorder (PTSD) and acute stress disorder (ASD) are defined by their temporal connection to a traumatic event in the individual's life. The post-traumatic disorders are characterized by a cluster of anxiety and dissociative symptoms, and by their interference with the patient's normal level of functioning. Magnetic resonance imaging (MRI) studies have shown that the high levels of sustained stress in some PTSD patients cause demonstrable damage to the hippocampus. Excessive amounts of stress hormones in brain tissue cause the nerve cells, or neurons, in parts of the hippocampus to wither and eventually die. One group of Vietnam veterans with PTSD had lost as much as 8% of the tissue in the hippocampus.

Substance abuse disorders

Stress is related to substance abuse disorders in that chronic stress frequently leads people to self-medicate with drugs of abuse or alcohol. Substance abuse disorders are associated with a specific type of strategy for dealing with stress called emotion-focused coping. Emotion-focused coping strategies concentrate on regulating painful emotions related to stress, as distinct from problem-focused coping strategies, which involve efforts to change or eliminate the impact of a stressful event. Persons who handle stress from a problem-oriented perspective are less likely to turn to mood-altering substances when they are under stress.

Adjustment disorders

DSM-IV-TR defines adjustment disorders as psychological responses to stressors that are excessive given the nature of the stressor; or result in impairment of the person's academic, occupational, or social functioning. The most important difference between the post-traumatic disorders and adjustment disorders is that most people would not necessarily regard those stressors involved in the latter disorder as traumatic. Adjustment disorder appear to be most common following natural disasters, divorce, becoming a parent, and retirement from work.

Causes of stress

The causes of stress may include any event or situation that a person considers a threat to his or her resources or coping strategies. A certain amount of stress is a normal part of life; it represents a person's response to inevitable changes in his or her physical or social environment. Moreover, positive events can generate stress as well as negative events. Graduating from college, for example, is accompanied by stress related to employment or possible geographical relocation and the stress of saying good-bye to friends and family, as well as feelings of positive accomplishment. Some researchers refer to stress associated with positive events as eustress.

Acute stress is defined as a reaction to something perceived as an immediate threat. Acute stress reactions can occur to a falsely perceived danger as well as to a genuine threat; they can also occur in response to memories. For example, a war veteran who hears a car backfire may drop to the ground because the noise triggers vivid memories, called flashbacks, of combat experience. Common acute stressors include loud, sudden noises being in a crowded space such as an elevator, being cut off in heavy traffic; and dangerous weather. Chronic stress is a reaction to a situation that is stressful but ongoing, such as financial worries or caring for an elderly parent. Modern life is stressful because changes in various areas of life have increased the number of acute and chronic stressors in most people's lives at the same time that they have weakened certain buffers or protections against stress.

Social changes

Social changes that have increased the stress level of modern life include increased population mobility and the sprawling size of modern cities. It is not unusual for adults to live hundreds of miles away from parents and siblings; and it is hard to make and keep friendships when people move every few years. In most large cities, many people live in apartment buildings where they do not know their neighbors. Social isolation and loneliness can produce chronic stress. A study done in Norway between 1987 and 1993 found that social support networks made a significant difference in lowering the impact of both acute and chronic stress on mental health.

Social scientists have observed that the increased isolation of married couples from extended families and friendship networks increases strains on the marriage. The rising divorce rate in the United States has been attributed in part to the loss of social supports that once helped to keep married couples together. The experience of divorce then adds to the stress level on the former spouses and the children, if any. A long-term study at the University of Pittsburgh has found that divorce is associated with a higher rate of premature death in men.

Economic changes

The rapid pace of change in manufacturing and other businesses means that few people will work at the same job for their entire career. In addition, corporate mergers and downsizing have weakened job security, thus producing chronic anxiety about unemployment in the minds of many employees. Many people work two jobs in order to make ends meet; and even those who work only one job often have to commute by car or train to their workplace. In many large American cities, traffic jams, cost of gasoline, and other problems related to commuting are a major factor in job-related stress. Another stress factor is sleep deprivation. Many people get only six or less hours of sleep each night even though the National Sleep Foundation estimates that most adults need 8–8-1/2 hours per night for good health. Fatigue due to sleep deprivation causes additional stress.

Lastly, economic trends have produced a "winner-take-all" economy in which the gap between the well-off and the average family is constantly widening. Socioeconomic status (SES) affects health in a number of ways. Persons of higher SES can afford better health care, are less likely to suffer from exposure to environmental toxins, and generally lead healthier lifestyles. In addition, chronic stress associated with low SES appears to increase morbidity and mortality among persons in these income groups.

Technological changes

Technology has proved to be a source of stress as well as a solution to some kinds of stress. Machines that help workers to be more productive also make their jobs more complicated and raise the level of demands on them. An office clerk in 2002 can produce many more letters per day than one in 1952, but is often expected to produce more elaborate, professional-looking documents as well as a higher number of them.

One specific technological development that has been singled out as a major stressor in modern life is the evolution of news reporting. For most of human history, people had to wait several days or even weeks to hear about the outcome of an election, a battle, or some other important event. Moreover, they usually heard only the news that affected their region or their country. Today, however, news is reported as soon as it happens, it is broadcast 24 hours a day, and it covers events around the world. This "communications overload," as it has been termed, is a source of genuine stress to many people, particularly when the newscast emphasizes upsetting or frightening events. It is not surprising that a common recommendation for lowering one's stress level is to cut down on watching television news programs. A team of physicians conducted telephone interviews following the events of September 11, 2001, in order to assess stress reactions in the general American population. The team found that the single most important factor was not geographical location relative to the attacks or educational level, but the amount of time spent watching televised reports of the attacks. The interviewers discovered that 49% of the adults had watched at least eight hours of television on September 11, and also that "extensive television viewing was associated with a substantial stress reaction."

Environmental changes

One significant source of stress in modern life is the cumulative effect of various toxic waste products on the environment. Studies of the aftermath of such environmental disasters as Three Mile Island and Chernobyl found that not only evacuees and people living in the contaminated area had high levels of emotional distress, but also cleanup workers and people living in nearby noncontaminated areas. In the case of Chernobyl, Russian physicians have reported a psychoneurological syndrome with several unexplained symptoms, including fatigue, impaired memory, muscle or joint pain, and sleep disturbances. The syndrome appears to be due to chronic emotional stress rather than radiation exposure.

Changes in beliefs and attitudes

Changes in beliefs that influence stress levels include the contemporary emphasis on individualism and a corresponding change in attitudes toward trauma. A number of observers have remarked that Western culture has moved away from its traditional high valuation of the family and community toward an increased focus on the individual. Some have called this trend the "Me First!" society—it emphasizes personal rights and entitlements rather than duties and responsibilities to others. It has, in the view of some physicians, encouraged people to dwell on trauma and its effects on them as individuals rather than to live up to more traditional ideals of composure and resilience in the face of distress.

Risk factors

Research indicates that some categories of people have a higher risk of stress-related illnesses and disorders:

• Children have very little control over their environments. In addition, they are often unable to communicate their feelings accurately.
• In elderly adults, aging appears to affect the body's response to stress, so that the relaxation response following a stressful event is slower and less complete. In addition, the elderly are often affected by such major stressors as health problems, the death of a spouse or close friends, and financial worries.
• Caregivers of mentally or physically disabled family members.
• Women in general.
• People with less education.
• People who belong to racial or ethnic groups that suffer discrimination.
• People who live in cities.
• People who are anger-prone. Chronic anger is associated with narrowing of the arteries, a factor in heart disease.
• People who lack family or friends.
• People who are biologically predisposed to an inadequate relaxation response.

Coping with stress

Coping is defined as a person's patterns of response to stress. Many clinicians think that differences in attitudes toward and approaches to stressful events are the single most important factor in assessing a person's vulnerability to stress-related illnesses. A person's ability to cope with stress depends in part on his or her interpretation of the event. One person may regard a stressful event as a challenge that can be surmounted while another views it as a problem with no solution. The person's resources, previous physical and psychological health, and previous life experience affect interpretation of the event. Someone who has had good experiences of overcoming hardships is more likely to develop a positive interpretation of stressful events than someone who has been repeatedly beaten down by abuse and later traumas.

Coping styles

The ways in which people cope with stress can be categorized according to two different sets of distinctions. One is the distinction between emotion-focused and problem-focused styles of coping, which was described earlier in connection with substance abuse. Problem-focused coping is believed to lower the impact of stress on health; people who use problem-focused coping have fewer illnesses, are less likely to become emotionally exhausted, and report higher levels of satisfaction in their work and feelings of personal accomplishment. Emotion-focused coping, on the other hand, is associated with higher levels of interpersonal problems, depression, and social isolation. Although some studies reported that men are more likely to use problem-focused coping and women to use emotion-focused coping, other research done in the last decade has found no significant gender differences in coping styles.

The second set of categories distinguishes between control-related and escape-related coping styles. Control-related coping styles include direct action, behavior that can be done alone; help-seeking, behavior that involves social support; and positive thinking, a cognitive style that involves giving oneself pep talks. Escape-related coping styles include avoidance/resignation, as in distancing oneself from the stressful event, and alcohol use. There appears to be no relationship between gender and a preference for control-related or escape-related coping.

Stress management

Stress management refers to a set of programs or techniques intended to help people deal more effectively with stress. Many of these programs are oriented toward job- or workplace-related stress in that burnout is a frequent result of long-term occupational stress. Most stress management programs ask participants to analyze or identify the specific aspects of their job that they find stressful, and then plan a course of positive action to minimize the stress. In general, the severity of job-related stress appears to be related to two factors: the magnitude of the demands being made on the worker, and the degree of control that she or he has in dealing with the demands. The workers who are most vulnerable to stress-related heart disease are those who are subjected to high demands but have little control over the way they do their job. In many cases, stress management recommendations include giving an employee more decision-making power.

Treatments for stress

There are a number of allopathic and alternative/complementary treatments that are effective in relieving the symptoms of stress-related disorders:

• Medications may include drugs to control anxiety and depression as well as drugs that treat such physical symptoms of stress as indigestion or high blood pressure.
• Psychotherapy, including insight-oriented and cognitive/behavioral approaches, is effective in helping people understand how they learned to overreact to stressors, and in helping them reframe their perceptions and interpretations of stressful events. Anger management techniques are recommended for people who have stress-related symptoms due to chronic anger.
• Relaxation techniques, anxiety reduction techniques , breathing exercises, yoga , and other physical exercise programs that improve the body's relaxation response.
• Therapeutic massage, hydrotherapy, and bodywork are forms of treatment that are particularly helpful for people who tend to carry stress in their muscles and joints.
• Aromatherapy , pet therapy, humor therapy, music therapy, and other approaches that emphasize sensory pleasure are suggested for severely stressed people who lose their capacity to enjoy life; sensory-based therapies can counteract this tendency.
• Naturopathic recommendations regarding diet, exercise, and adequate sleep, and the holistic approach of naturopathic medicine can help persons with stress-related disorders to recognize and activate the body's own capacities for self-healing.

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

Gleick, James. Faster: The Acceleration of Just About Everything. New York: Pantheon Books, 1999.

Herman, Judith, MD. Trauma and Recovery. 2nd ed., revised. New York: Basic Books, 1997.

"Psychosomatic Medicine (Biopsychosocial Medicine)." Section 15, Chapter 185 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2000.

Selye, Hans. The Stress of Life. Revised edition. New York: McGraw-Hill Book Company, Inc., 1976.

PERIODICALS

Adler, N. E., and K. Newman. "Socioeconomic Disparities in Health: Pathways and Policies. Inequality in Education, Income, and Occupation Exacerbates the Gaps Between the Health 'Haves' and 'Have-Nots.'" Health Affairs (Millwood) 21 (March-April 2002): 60-76.

Evans, O., and A. Steptoe. "The Contribution of Gender-Role Orientation, Work Factors and Home Stressors to Psychological Well-Being and Sickness Absence in Male- and Female-Dominated Occupational Groups." Social Science in Medicine 54 (February 2002): 481-492.

Levenstein, Susan. "Stress and Peptic Ulcer: Life Beyond Helicobacter." British Medical Journal 316 (February 1998): 538-541.

Lombroso, Paul J. "Stress and Brain Development, Part 1." Journal of the American Academy of Child and Adolescent Psychiatry 37 (December 1998).

McEwen, Bruce. "Stress and Brain Development, Part 2." Journal of the American Academy of Child and Adolescent Psychiatry 38 (January 1999).

Matthews, K. A., and B. B. Gump. "Chronic Work Stress and Marital Dissolution Increase Risk of Posttrial Mortality in Men from the Multiple Risk Factor Intervention Trial." Archives of Internal Medicine 162 (February 2002): 309-315.

Mayer, Merry. "Breaking Point (Job Stress and Problem Employees)." HR Magazine 46 (October 2001): 79-85.

Olstad, R., H. Sexton, and A. J. Sogaard. "The Finnmark Study: A Prospective Population Study of the Social Support Buffer Hypothesis, Specific Stressors and Mental Distress." Social Psychiatry and Psychiatric Epidemiology 36 (December 2001): 582-589.

Pastel, R. H. "Radiophobia: Long-Term Psychological Consequences of Chernobyl." Military Medicine 167 (February 2002): 134-136.

Schuster, Mark A., Bradley D. Stein, Lisa H. Jaycox, and others. "A National Survey of Stress Reactions After the September 11, 2001, Terrorist Attacks." New England Journal of Medicine 345 (November 15, 2001): 1507-1512.

Summerfield, Derek. "The Invention of Post-Traumatic Stress Disorder and the Social Usefulness of a Psychiatric Category." British Medical Journal 322 (January 13,2001): 95-98.

van der Kolk, Bessel. "The Body Keeps the Score: Memory and the Evolving Psychobiology of PTSD." Harvard Review of Psychiatry 1 (1994): 253-265.

ORGANIZATIONS

The American Institute of Stress. 124 Park Avenue, Yonkers, NY 10703. (914) 963-1200. Fax: (914) 965-6267. <www.stress.org.>.

Anxiety Disorders Association of America. 11900 Parklawn Drive, Suite 100, Rockville, MD 20852-2624. (301) 231-9350. <www.adaa.org>.

Stress and Anxiety Research Society (STAR). <www.star-society.org>.

See also Creative therapies; Diets; Nutrition and mental health

Rebecca J. Frey, Ph.D.