The naturalistic course of unipolar major depression in the absence of somatic therapy.

The goal of the study was to describe the naturalistic course of unipolar major depression in subjects not receiving somatic therapy for their depressive illness. Affectively ill individuals were recruited into the Collaborative Depression Study and followed prospectively for up to 15 years. One hundred thirty subjects who recovered from their intake episode of major depression subsequently experienced a recurrence that went untreated for at least 4 weeks following onset of the recurrence. The duration of the recurrent episode was examined using survival analytic techniques. Of the 130 subjects, 46 obtained somatic therapy at some time during the course of their depressive illness, while 84 subjects received no somatic therapy throughout their entire depressive episode. Survival analysis, which accounts for these 46 individuals by censoring their episodes at the time treatment was obtained, yielded a median time to recovery of 23 weeks. In the subsample of 84 subjects whose depressive illness went untreated from its inception through its resolution, the median time to recovery was 13 weeks. These results suggest that there is a high rate of recovery in individuals not receiving somatic treatment of their depressive illness, particularly in the first 3 months of an episode. Because treatment-seeking behavior is known to be associated with a worse prognosis, 23 weeks probably represents a lower-limit approximation of the median duration of an untreated depressive episode.