Successful Aging: A Neuroscientist Explores the Power and Potential of Our Lives

by Daniel J. Levitin

When a situation is perceived as being stressful (because it is novel, unpredictable, uncontrollable, or painful), two major classes of stress hormones are secreted, catecholamines and glucocorticoids. They are the first hormonal systems to respond to stress. The short-term secretion of these hormones in the face of a challenge serves an adaptive purpose and leads to the fight-or-flight response (allostasis). However, the same stress hormones that are essential for survival can have damaging effects on both physical and mental health if they are secreted over a longer period of time (called allostatic load). This happens because when these primary stress hormones are increased for long periods of time, it leads to dysregulation of other major biological pathways in the body and the brain, for example, insulin, glucose, lipids, and neurotransmitters. This in turn causes a dysregulation of various other operations, such as the immune system, the digestive system, the reproductive system, cardiac health, and mental health.