Stress as a Medical and Scientific Idea and Its Implications

Abstract

Publisher Summary Stress is defined as a state of threatened homeostasis, which is re-established by a complex repertoire of physiological and behavioral adaptive responses of the organism. Hormones participate in a crucial fashion in the coordination of both basal and threatened homeostasis. The stress response is subserved by a complex system located in both the central nervous system (CNS) and the periphery. This system receives and integrates a large diversity of neurosensory (visual, auditory, somatosensory, nociceptive, visceral), blood-borne, and limbic-cortical signals, which arrive through distinct pathways. Activation of the stress system leads to behavioral and physical changes that are remarkably consistent in their qualitative presentation. These changes are normally adaptive and improve the chances of the individual for survival. There has been an exponential increase in knowledge regarding the interactions among the components of the stress system and between the stress system and other brain elements involved in the regulation of emotion, cognitive function, and behavior, as well as with the axes responsible for reproduction, growth, and immunity. This new knowledge has allowed association of stress system dysfunction characterized by sustained hyperactivity or hypoactivity to various pathophysiologic states that cut across the traditional boundaries of medical disciplines. These include a range of psychiatric, endocrine, and inflammatory disorders and/or susceptibility to such disorders. Of special interest is atypical-seasonal depression, which is associated with a hypofunctional stress system with weight gain in the dark winter months and/or autoimmune manifestations, and melancholic depression, which is associated with a hyperfunctional stress system and immunosuppression.