There is a lack of consensus on how to best define the concept of stress. Concerns related to the scientific status of the construct have led some authors to suggest that it be abandoned altogether or restricted to nontechnical usage. Even at the level of physiology, the mechanisms involved in a stress response cannot be adequately differentiated from anxiety or depression. Likewise, responses to stress are broad and can include anger and hostility, emotional suppression or repression, and disengagement, all of which are similarly confounded with other constructs. Further, the nature of stressors can be confounded with traumatic events depending on how the individual experiences the event.
There is compelling, albeit limited, research that has demonstrated a relationship between the experience of negative life events, especially those that are objectively measured and chronic in nature, and functional changes in the immune system. The possible association between stress and the development and progression of serious illnesses such as coronary heart disease and cancer will need to be studied more extensively before researchers have a better understanding of the potential interplay between them. Some effective interventions for stress have been developed, including stress management techniques, but these are closely related to relaxation treatment approaches designed to treat anxiety. It does appear that the treatment literature emphasizes a cognitive behavioral perspective that, given the role of appraisals and coping mechanisms, holds considerable promise.
The Concept of Stress
The term stress is typically meant to describe an individual’s response to negative life events and involves cognitive, behavioral, emotional, and physiological components. Due to its multifaceted nature, the concept of stress has proved to be an imprecise term for the purpose of scientific investigations. Stress has been operationalized in many ways, and as such, it is often confounded with depression, anxiety, lack of social support, Type A behavior, hostility, and anger. Although no consensus has been achieved regarding the definition of stress, one generally accepted conceptualization of stress is that it is a response to a threat or environmental challenge that exists on a continuum between excitement and anxiety and is normally experienced as tension or negative affect. The severity of the individual’s response depends on the degree to which he or she feels a sense of control over the challenge and the level of belief he or she has about the ability to cope effectively with the challenge. Stress has various dimensions, including its duration (acute vs. chronic), quantity (discrete events vs. cumulative events), and quality (interpersonal vs. noninterpersonal events).
Several factors contribute to a stress response. In order for a stress response to occur, there must be the presence of a stressor. Stressors are events or conditions that present a demand or challenge or in some way constrain the individual and may involve catastrophic events (e.g., a natural disaster or being the victim of violence or war), major life changes, minor events, or chronic conditions (e.g., occupational stress). Lazarus and Folkman also noted the importance of cognitive appraisal in the stress process. An event needs to be judged in two ways: One is its relevance to one’s physical and psychological well-being, and the other is whether one has the resources available to cope with the problem. This appraisal process influences the quality and intensity of one’s emotional response as well as guides the selection of either emotion-regulation or problem-solution strategies for coping.
Physiology of Stress
There also appears to be consensus that stress involves a physiological response. While Selye initially popularized the concept of stress, the first researcher to describe the phenomenon was Cannon, who described the “fight or flight” response. Selye later observed a set of generalized physical processes that he termed the general adaptation syndrome (GAS), which is the body’s response to the awareness of a harmful stimulus and the interpretation of that stimulus as threatening. Current conceptualizations underscore how stress is mediated through the nervous, endocrine, and immune systems. The autonomic nervous system, with its sympathetic and parasympathetic branches, serves a particularly important role in the fight or flight response. The interplay of these systems has implications for the effects of stress on health and illness. For example, the role of one of the cranial nerves, the vagus, is involved with sympathetic activity with regard to heart rate and heart rate variability (HRV). Reduced HRV has been implicated in cardiac disease as well as in both anxiety and depression. Similarly, a real or perceived threat involves the hypothalamic pituitary axis, which activates a number of hormonal responses that have long-term implications for physical functioning.
The Assessment of Stress
Due to its multifaceted nature, stress has been assessed in a variety of ways. Given that life change is commonly implicated in the onset of the stress response, it is not surprising that this has been one focus of stress assessment. Holmes and Rahe developed a scale that incorporates both positive and negative life events that are weighted based on the degree of stress involved. There are also measures that assess the impact of traumatic events as well as daily hassles. In addition to self-report measures, there are interview and observational measures, such as those developed to assess Type A personality. There is also a substantial body of research examining how personality may be a risk factor for illness, with emphases on constructs as broad as neuroticism, and including anger, attachment style, emotional suppression, resiliency, helplessness, shyness, and so on. Given the emphasis on biological systems, stress has also been assessed in the laboratory measuring such diverse characteristics as the heart rate and HRV, skin conductance, muscle tension, and catecholamine and neurohormone levels, among others.
The Relationship between Psychological Stress and Physical Illness
There is compelling empirical evidence supporting the connection between stressful life events and changes in the immune system. In a meta-analytic review of studies examining the influence of stress on immunity changes, researchers found a significant relationship between stress and both functional and enumerative immune measures. The results indicated that objective reports of stress were related to greater immune changes than subjective self-reports of stress were, interpersonal life events were related to greater changes in some immune outcomes compared to nonsocial life events, and long-term naturalistic stressors were associated with immunological changes. A second meta-analysis of over 300 investigations of the relationship between stress and changes in the immune system found that acute, time-limited stressors brought about adaptive immunological changes consistent with fight-or-flight responses, while chronic stressors were correlated with the suppression of cellular and humoral indices. Similar to the former meta-analysis, this review indicated that subjective reports of stress were not significantly related to immunological changes.
Conflicting evidence exists regarding the impact of stress on the onset or progression of coronary heart disease and cancer. There appears to be some evidence that acute and chronic stress may have important effects on coronary heart disease. However, this relationship has been viewed with some skepticism given the lack of consensus about how stress should be defined and measured as well as the complex nature of coronary disease. Stress may contribute to the development of cancer through its effects on primary cellular function, such as DNA repair, and it also appears that an individual’s level of adjustment to having cancer may affect the progression of the cancer. The mechanisms involved in the relationship between stress and specific diseases are highly complex and therefore require additional prospective community-based studies to define this relationship.
Despite 2 decades of research in the area of stress and coping, no gold standard interventions have been developed for managing stress. Research on coping behaviors indicates that the manner in which a person responds to stress is greatly influenced by longstanding characterological traits and therefore may be only somewhat amenable to psychological interventions. However, researchers have demonstrated that stress management interventions can bolster the immune system during treatment for HIV-positive patients and that stress management, coping skills training, and social support have been shown to affect progression of cancer. An emerging area of research is that of positive psychology, which focuses on catalyzing positive change in the face of overwhelming stress. There are a growing number of research studies that demonstrate that interventions consistent with positive psychology are able to promote positive mood in individuals suffering from chronic stress. For example, researchers were able to increase positive affect in AIDS caregivers with the use of problem-focused coping, positive reappraisal, and the reframing of ordinary life events with positive meaning.
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