Neuroendocrine mechanisms and the precipitation of depression by life events.

It is now generally accepted that stressful life events and chronic difficulties can trigger the onset of depression in predisposed individuals. However, although much is known of the neurobiology of stress, few attempts have been made to provide a biological explanation for the mechanisms whereby life events might trigger depression. Enough is now known of the central control of hypothalamic pituitary adrenal (HPA) function and its response to stress to permit an examination of its role in the neurobiology of the triggering of depression by stress. This evidence is reviewed, and the proposal explored that stress triggers depression by a genomic action of corticosteroids.