The course of development of mania in patients with recurrent depression.

The authors attempted to assess the extent to which bipolar patients are misdiagnosed as unipolar by evaluating the development of mania in patients who had recognized bipolar illness and by means of follow-up data on patients who had recurrent depressions. Mania occurred early in the course of bipolar illness: almost 80% of the bipolar patients were initially hospitalized for mania. Follow-up data and theoretically based calculations suggest that the chance of a patient with recurrent depressions becoming bipolar is about 5%. Based on these findings, the authors make suggestions for the classification of unipolar patients.