Time to recovery of an inception cohort with hitherto untreated unipolar major depressive episodes

Background Generalisability of existing studies on the naturalistic history of major depression is undermined by overrepresentation of in-patients and tertiary care academic centres, inclusion of patients already on treatment and/or incomplete follow-up. Aims To report the time to recovery of an inception cohort of unipolar major depressive episodes. Method A multi-centre prospective follow-up study of patients with a mood disorder, who had been selected to be representative of the untreated first-visit patients at 23 psychiatric settings from all over Japan. Results The median time to recovery of the index episode after treatment commencement was 3 months (95% CI 2.5-3.6): 26% of the cohort reached asymptomatic or minimally symptomatic status by I month, 63% by 3 months. 85% by 12 months and 88% by 24 months. Conclusions Our estimate of the episode length was 25-50% shorter than estimates reported in the literature.