Recurrent brief depression : the Zurich study

The initial conception of manic depressive illness by Kraepelin included short and mild depressive and hypomanic states in the nosologic category of affective illnesses. A longitudinal epidemiologic study in Switzerland (the Zurich Study) identified brief, but recurrent, episodes of depression with severity of symptoms, impairment, and distress equivalent to major depression. The concept of recurrent brief depression was further confirmed in recent community and general practice studies. The diagnostic criteria for recurrent brief depression require the presence of at least five of nine depressive symptoms analogous to the symptoms of major depression, yet a duration of less than 2 weeks (in general 1 to 3 days), a recurrence of at least 12 times a year, and the evidence of work impairment