Stress, emotions and health: where do we stand?

Abstract

Our representation of the way stress influences the development and progression of disease has been shaped by physiological stress theories. According to these theories, the organism's reaction to any stimulus that threatens its homeostasis is stereotyped and involves both the sympathetic medullary adrenal axis and the pituitary-adrenal axis. These systems can overtax the organism's resistance, especially when they are chronically activated. However, physiological stress responses are not stereotyped. They depend qualitatively and quantitatively on the psychological dimensions of the situation, including the subject's ability to predict and control the occurrence of stressors. Studies of the effects of stress and emotions and immunity have confirmed the importance of predictability and controllability. In addition, they have made clear that if stress and emotions can influence emotions, reciprocally immune factors have profound influences on mood and behaviour. These reciprocal relationships between the brain and the immune system are mediated by an intricate network of neural and molecular connections. Because of this reciprocity, it is difficult if not impossible to isolate one term of the relationship and claim it is causally related to the other one. This explains why the field has moved away from the consideration of the role of psychosocial factors and emotions in the pathogeny of somatic diseases to more pragmatic questions such as the way patients cope with their disease and the medical system.