The association between stress and health has been documented for decades. Stress can affect health both directly through its physiological effects and indirectly from maladaptive behaviors such as overeating or smoking. While great advances have been made in our understanding the role of stress and its deleterious effects on health, much still remains to be elucidated.
The term “stress” is used to represent a variety of concepts including: (a) an environmental situation; (b) appraisal of this situation; (c) the response to the situation or appraisal; and (d) a person’s capacity to respond to environmental situations in general. The latter three are described here while the first is referred to as a stressor.
Much of the early work on stress focused on the “fight-or-flight” reaction to stress originally described by Cannon in 1932. This work was extended by Hans Selye as a three-step process called the general adaptation syndrome (GAS). Selye speculated that people exhibited changes in response to stressors including an alarm reaction, resistance, and exhaustion. Each stage would produce both physiological and behavioral changes, so if curative measures were not taken, then both physical and psychological deterioration would occur.
Stress was speculated to help species survive under a variety of conditions. The early response to acute stress enables the organism to face the stressor by enhancing immune function and increasing blood pressure and heart rate to prepare them to meet the physical demands from the stressor, and in the longer run, make more fuel available for sustained activity. However, as seen from observations of animals in their natural habitat, the stressors are most often for a limited duration. The stress system was not designed to adequately face stressors of lingering duration, such as unemployment or unreasonable job demands. When the system is overburdened by constant or consistent stressors, there is a chronic “wear and tear” that can render the organism more vulnerable to disability and disease.
While the “fight-or-flight” response has been studies for many years, recent research has suggested that women may respond differently to stressors than men. Some researchers argue that while women do experience the “fight-or-flight” phenomena when under acute stress, another stress response that women utilize is the “tend and befriend.” “Tend and befriend” means that women under stress will nurture themselves and their children (i.e., tend) and will form alliances with others (i.e., befriend). This stress response also is associated with the survival of species in that females would need to protect their young in stressful situations.
Stress is described as one of several factors (e.g., lifestyle, sleep) that contribute to allostatic load, which was described by McEwen and Stellar in 1993. When the body is subjected to consistent and repeated strain, the body is predisposed to disease. This state is called allostatic load. Allostatic load can affect health states via three mechanisms. First it can affect the primary mediators, meaning the chemical mediators such as cortisol, norepinephrine, and the like. Alternatively, it can affect the systems that are mediated by the primary mediators, such as cellular events. Finally, allostatic load can affect health states by secondary mediators, meaning via more integrated processes such as blood pressure or metabolic profiles.
Stress has been shown to be involved in a variety of illnesses including hypertension, atherosclerosis, osteoporosis, irritable colon, and peptic ulcers. Stress has also been related to exacerbation of multiple sclerosis and hampering control of both types of diabetes. Fibromyalgia, chronic fatigue syndrome, and rheumatoid arthritis are related to processes resulting from chronic stress. Finally, it has been estimated that approximately two thirds of all visits to the family doctor are for stress-related disorders.
While stress has been associated with a number of illnesses, it is difficult to identify the precise mechanism that is responsible for disease. Animal studies of mice and primates allow for controlled studies, which have shown that inducing psychological stress results in distinct illness including atherosclerosis and hypertension. However, studies in humans are complicated by the fact that responses to stressors are variable and characteristics of the individual experiencing the stressor become important. In addition, the duration, frequency, and severity of stressors are also difficult to measure. Over the past 30 years, social scientists have grappled with these measurement and conceptual difficulties and have tried to refine measurements and theoretical frameworks to better elucidate the complicated role between stress and subsequent illness or disease.
In the 1960s and 1970s, social scientists expanded the lines of research on stress and developed ways to identify and measure potential stressors. Life event scales were developed to measure both positive and negative life events that might be considered stressful. Researchers found that those who reported high scores on the scales (meaning more stressful life events) were also more likely to experience illness compared to those with low scores. This research was extended to measuring the participant’s subjective rating of the impact of the event, rather than just whether the event happened. This meant that a given event could be perceived differently depending on the person experiencing the event. Researchers believed it was the subjective perception that was important in determining deleterious effects of stress.
Subsequent research has shown that some personality types and/or psychological states are related to stress and disease. Early research focused on “type A” personalities, which are characterized by aggressiveness, haste, hurriedness, competitiveness, and the like. This personality trait is considered a risk factor for cardiovascular disease and angina, although conflicted research exists that finds no effect or effects only for certain groups of individuals (i.e., men in white-collar jobs).
Psychological states also include dispositional coping styles, which are enduring traits of an individual thought to influence coping efforts. These coping styles can moderate the association between stress and coping efforts. Optimism is the most widely researched disposi-tional coping style. Optimism is defined as having positive rather than negative expectations for the future. These positive expectations are consistent over time and across situations. Optimistic individuals have been found to recover faster after myocardial infarction and experience fewer physical symptoms during life stres-sors. Furthermore, optimists have been shown to have better psychological adjustment during and after major illnesses such as cancer and HIV.
Another dispositional trait that has received a lot of attention is locus of control. Locus of control is defined as a person’s belief in his or her ability to control events through their own efforts. Persons with an internal locus of control believe that they can control events through their efforts (i.e., the environment is controllable) while those who have an external locus of control feel that outside influences control events in their lives. Those with an internal locus of control have been found to have different coping mechanisms for stress. Specifically, people with an internal locus of control are more likely to use acting coping styles and increase their efforts to control the outcome.
Two different information-seeking styles, monitoring and blunting, have been shown to be related to various health-related outcomes. Monitoring is the seeking of relevant information and is related to a perceived heightened risk and excessive worry. This excessive worry has been related to negative outcomes, such as increased nausea and vomiting in cancer patients undergoing chemotherapy. Blunting, on the other hand, is the avoidance of such information. While monitoring has been shown to have negative effects from excessive worrying, it can also have beneficial effects. Monitors may be more likely to actively seek important health information when they are ill or suspect that they are ill and may also be more likely to adhere to recommended health practices.
Several factors have been shown to buffer or moderate the effects of stress, in particular, social support and stress management interventions. A buffering or moderating effect means that stress would not be deleterious under certain situations where there was a protective element. Social support has beneficial direct effects on well-being but has also been shown to have “stress-buffering” effects on well-being. In addition, stress management interventions such as biofeedback have shown promise in reducing the harmful effects of stress.
Women, in particular, can face stress from a variety of different areas including love relationships, personal success, job stress, physical health, parent-child relationships, personal time, and social relationships. The stress from each of these areas has been shown to vary across age groups. Furthermore, many women today face challenges from trying to balance stress from multiple areas simultaneously, such as stress from work, children, and love relationships. While men often face more immediate occupational hazards, women are more prone to stress-related illnesses. In addition to dealing with the multiple roles previously described, women as a group are less likely to be in positions of power and therefore less likely to be able to control their environment, a situation which has been shown to be related to increased stress. Researchers have speculated that women today may be disadvantaged in that they are expected to achieve a (previously deemed) “male” standard of achievement at work and at the same time achieve an old-fashioned female standard for perfection at home as well.