Chronicity of depressive episode in relation to antidepressant-placebo response

Pooled data from three 6-week placebo-controlled, double-blind, phase III clinical trials, designed to assess the efficacy of newer antidepressants, were retrospectively analyzed to study the relationship between chronicity of presenting depressive episode and response to placebo, imipramine, and adinazolam. One hundred forty-six depressed outpatients met criteria for inclusion into this study; 80 received placebo treatment, 27 imipramine and 39 adinazolam treatment. Consistent with our hypothesis the response to placebo was low in subjects who were depressed for 1 year or longer (22.6%) as compared to a higher response rate (44.9%) among those who were not as chronically depressed. The response to imipramine and adinazolam was not related to the duration of presenting depressive episode. The implications of these findings are discussed.