It has been shown in placebo controlled studies of prophylactic treatment of suicidal behaviour in patients not suffering from major depression that brief episodes of depression predict further suicidal behaviour. 2. In a prospective follow up study of patients with a history of repeated suicidal behaviour it appears that almost all suffered recurrent episodes of brief depression, mainly of moderate to severe intensity. Two thirds of the episodes lasted between two and four days. The recurrences were frequent, irregular, and apparently unpredictable. 3. The episodes were distinguishable from major depression only by the short duration.
