Double depression and episodic major depression: demographic, clinical, familial, personality, and socioenvironmental characteristics and short-term outcome.

The authors compared 31 outpatients with double depression to 50 outpatients with episodic major depression. Patients with double depression exhibited significantly greater impairment, more severe depressive symptoms, greater comorbidity, more personality disturbance, lower levels of social support, more chronic strains, and higher rates of bipolar II and nonbipolar affective disorders in first-degree relatives. In addition, in a 6-month follow-up, the patients with double depression were significantly less likely to recover, and a higher proportion experienced hypomanic episodes than did patients with episodic major depression. These data provide strong support for the clinical significance of double depression.