The effect of the first manic episode in affective disorder: a case register study of hospitalised episodes

Abstract

Background. It is poorly understood how the course of illness in depressive patients is affected by a manic episode. Method. The course of hospitalised episodes was compared for patients with depressive episodes only, patients who presented with a manic or circular first episode and patients who presented with a depressive first episode and later developed mania. The Danish psychiatric central register was used as a study base, including all hospital admissions with primary affective disorder in Denmark during 1971–1993. Results. A total of 17,447 patients presented with a depressive first episode and 2903 patients with a manic or circular first episode. Among the 17,447 depressive patients, 762 patients presented with mania at later episodes (4.4%). Younger age at onset was associated with increased risk of developing mania. Patients who had a late first manic episode had the same rate of subsequent recurrence as patients with mania at first episode and this rate was higher than the rate of recurrence for patients who remained having depressive episodes only. Time since first manic episode was without importance in relation to the risk of subsequent recurrence. Conclusion. Patients who present with depression and later develop mania have from onset the same risk of recurrence as initially bipolar patients. Limitation. The data relate to admissions rather than episodes. Clinical relevance. Younger patients who present with depression have increased risk of developing bipolar disorder.