Pituitary-adrenal disinhibition in depression: marker of a subtype with characteristic clinical features and response to treatment?

The data from a series of studies in different patient samples are consistent in showing that resistance to dexamethasone suppression is selectively associated with primary major depressive disorder. In addition, nonsuppressors appear to have more depressive episodes, show greater improvement during hospitalization, tend to be older than suppressors, and may have a specific disturbance in cognitive function. Preliminary data suggest that nonsuppressors and suppressors respond preferentially to different antidepressants. These data raise the possibility that pituitary-adrenal disinhibition, as assessed by the dexamethasone suppression test, is associated with a depressive subtype having a distinctive pathophysiology, clinical course, and treatment response.