Highly recurrent unipolar may be related to bipolar II.

Unipolar and bipolar disorders may be subgroups of a single mood disorder, of which the key feature is not polarity, but the episodic, recurrent course. The aim of this study was to determine whether highly recurrent unipolar was related to bipolar II, by comparing clinical and family history features. Eighty-nine consecutive unipolar and 151 consecutive bipolar II outpatients, presenting for major depressive episode (MDE) treatment, were interviewed using the Structured Clinical Interview for DSM-IV (SCID) and the Family History Screen. Unipolar patients were divided into highly recurrent (>4 MDEs) (HRUP) and low recurrent (</=4 MDEs) (LRUP). HRUP had significantly fewer atypical features and less bipolar II family history than bipolar II, while age at onset, axis I comorbidity, and depression chronicity were not significantly different. HRUP had statistically significant lower age at onset, more axis I comorbidity, more depression chronicity, and clinically significant more atypical features and more bipolar II family history than LRUP. Results suggest that HRUP could be midway between bipolar II and LRUP. Pages and Dunner (1997) view that recurrent unipolar and bipolar II could be part of a single mood disorder, and Goodwin and Jamison (1990) view that recurrence is the key feature of mood disorders are partly supported by the findings. Copyright 2002, Elsevier Science (USA). All rights reserved.