The significance of past mania or hypomania in the course and outcome of major depression.

Patients with primary major depression (N = 372) were followed for 2 years to determine the prognostic importance of past manic or hypomanic episodes. While bipolar I and bipolar II patients were more likely to relapse and bipolar I patients were more likely to attempt suicide, these patients resembled nonbipolar depressed patients in likelihood of recovery and psychosocial impairment in various areas. Compared to nonbipolar patients, those with bipolar I depression were much more likely to develop mania, while bipolar II patients were more likely to develop hypomania. Cycling during the index episode predicted a relatively low likelihood of recovery for bipolar I patients but had no apparent prognostic significance for patients with bipolar II illness.