The usefulness of DST in predicting response to antidepressants: a placebo-controlled study.

Seventy-two out-patients, 55 years or older, suffering from major depression were treated with either nortriptyline or phenelzine for seven weeks under placebo-controlled double-blind conditions. The dexamethasone suppression test (DST) was administered at baseline and at weeks 3 and 7 of treatment, and its usefulness in predicting and/or paralleling clinical response was examined. No correlation was found between baseline DST results and treatment response with antidepressants. Of 13 patients whose abnormal baseline DSTs normalized during treatment, six were responders and seven were nonresponders (P = 0.24). However, all (seven) patients whose DSTs persisted to be abnormal throughout the seven weeks did not respond. The authors conclude that the DST has not been shown to have practical value as an indicator of impending recovery from major depression in the elderly, but its failure to normalize may have ominous prognostic significance.