Stress, Health, and Illness
Angela Liegey Dougall
University of Pittsburgh Cancer Institute
The customary introduction to stress suggests that it is still a matter of scientific debate, despite the fact that it is a common and influential state. It shares aspects of mind and body, representing a good instance of more holistic integration of these constructs. It is also a crosscutting process, influencing a wide array of illnesses, health behaviors, and aspects of health and well-being. Despite the general lack of a consensus on a precise definition of stress or the best approach to measuring it, there is considerable evidence to suggest that stress has important effects on physical and mental states, pathophysiology of disease, and performance (for reviews see Baba, Jamal, & Tourigny, 1998; Biondi & Zannino, 1997; S. Cohen & Williamson, 1991; McEwen & Stellar, 1993). This chapter considers conceptual models of stress, the broad array of behaviors and bodily systems involved in the stress response, and the impact of stress on chronic disease processes. Differences in the consequences of acute and chronic stress, as well as the implications of observed differences between them are also explored.
Perhaps the most difficult aspect of studying stress is deriving a widely accepted definition of it. Most theorists agree that stress is (or can be) adaptive, that it is associated with threatening or harmful events, and that it is typically characterized by aversive or unpleasant feelings and mood. Beyond this, there are few areas of universal agreement. Some theorists have argued that stress can be positive, but others have insisted that it is a fundamentally aversive state (e.g., Baum, 1990; Selye, 1956/1984). Some have pointed out apparently simultaneous biological and psychological activation, suggesting that stress is an emotion, and some have described stress as a general state of arousal associated with taking strong action or dealing with a strong stimulus (e.g., Baum, 1990; Mason, 1971). Stress has been variously defined as a stimulus, as a response, and as a process involving both. It has been described as both specific and nonspecific responses to danger with little evidence to support one or another contention. However, it appears to be a fundamental component of adjustment and adaptation to environmental change, and as such has assumed a critical role in theories of human evolution. From these many notions have come a few major theories of stress that reflect integration and synthesis of prior theories and that describe a pattern of responses to threat, harm, or loss.
A history of the stress concept could begin with early philosophers, but modern stress theory really began with Cannon's work early in the 20th century. Cannon (1914) was interested in the effects of stress on the sympathetic nervous system (SNS) and with application of the concept of homeostasis to interaction with the environment. Stressful events elicited negative emotions associated with SNS activation and disequilibrium in bodily systems. This activation was associated with the release of sympathetic adrenal hormones (i.e., epinephrine, norepinephrine), which prepared the organism to respond to the danger posed, characteristically by fighting or fleeing. This early description of stress did not consider the measures of activation or persistence, focusing solely on SNS arousal and release of sympathetic hormones.