Serial dexamethasone suppression test results during antidepressant therapy: Relationship to diagnosis and clinical change

Thirty-two outpatients with major depression of mild to moderate severity were given a 1 mg dexamethasone test (DST) after 1 week of placebo. Those who failed to show a response to placebo began a 6-week course of desipramine treatment. Severity ratings and the DST were repeated during biweekly visits. DST results robustly validated Winokur's familial subtyping and the primary/secondary distinction only when multiple results were considered. The use of multiple DSTs doubled the sensitivity of this test to primary depression and to familal pure depressive disorder without affecting specificity. Based on these data, a single abnormal DST result is considerably more meaningful than a single normal one. This finding may have particular importance to outpatients.