Residual symptoms in depression an emerging therapeutic concept.

Cushing's syndrome is due to chronic glucocorticoid excess that may have various etiologies. The most common endogenous form is pituitary-dependent bilateral adrenal hyperplasia, which is termed Cushing's disease. Major depression occurs in more than half of the cases. The presence of depressive symptoms connotes severity of clinical presentation and, in patients with hypothalamic-pituitary forms, entails prognostic value. Medical treatment may be used while awaiting more definitive solutions for the illness by surgery. The inhibitors of steroid production (e.g., ketoconazole, metyrapone and aminoglutethimide), rather than antidepressant drugs, are generally successful in lifting depression as well as other disabling symptoms. Since central serotonergic regulation could have a role in the course of Cushing's disease, serotonin antagonists (e.g., cyproheptadine, ritanserin and ketanserin) have been employed. Findings related to the pharmacological response of depression in Cushing's disease were found to have implications for the pathophysiology of depression and the potential involvement of the hypothalamic-pituitary-adrenal axis (HPA axis) in resistance and tolerance to antidepressant drugs. The use of serotonergic drugs in Cushing's disease may yield important insights in the understanding of serotonergic regulation both in Cushing's disease and in the HPA axis in nonendocrine major depression.