Bipolar II disorder and suicidal behavior.

Despite the fact that the nosologic position of bipolar II disorder continues to be debated, several lines of research indicate that it is a distinct nosologic category that should be separated from both bipolar I and unipolar major depression. This review of the authors' and others' work demonstrates that the lifetime risk of suicide attempts is highest in bipolar II and lowest in unipolar patients, whereas risk is intermediate in bipolar I patients. Moreover, two reports show that bipolar II patients are over represented among suicide victims. Clinicians must take great care in not missing this diagnosis, which, when untreated, has ominous prognostic implications.