The dexamethasone suppression test in depression.

The DST does appear to be abnormal in a sizable subgroup of patients with major depressive disorder, particularly those characterized as "endogenomorphic" or "melancholic." At present the available data seem clear in indicating this abnormality is significantly less common in normal controls and patients without affective illness. The test holds considerable promise in helping to define new subgroups of depressed individuals for further study. In terms of its ability to predict treatment response to an adequate course of somatic therapy, the test does not appear to be of value, and the clinician should still be guided by the clinical presentation and history in initiating or choosing between various somatic treatments. With further attention to issues of diagnosis and DST methodology this strategy could help in addressing questions of differential diagnosis in potential "variants" of affective illness and providing a better understanding of the pathophysiology of depression.