Comparison of DSM-III-R chronic major depression and major depression superimposed on dysthymia (double depression): Validity of the distinction

The nosology of chronic depression has become increasingly complex since th e publication of the revised third edition of the Diagnostic and Statistica l Manual of Mental Disorders (DSM-III-R; American Psychiatric Association, 1987), but there are few data available to evaluate the validity of the dis tinctions between the subtypes of chronic depression. The validity of the d istinction between DSM-III-R chronic major depression (CMD) and major depre ssion superimposed on dysthymia (double depression, DD) was examined. Parti cipants were 635 patients with chronic depression in a 12-week trial of ant idepressant medications. Patients with CMD, DD, and a 3rd group with a chro nic major depressive episode superimposed on dysthymia (DD/CMD) were compar ed on demographic and clinical characteristics, family history, and respons e to treatment. Few differences were evident, although the depression of pa tients with DD/CMD tended to be more severe.