Rapid cycling in unipolar and bipolar affective disorders

To characterize the nature of rapid cycling affective disorders, the authors analyzed mood fluctuation patterns in 570 patients with affective disorders hospitalized in 1960, 1975, or 1985. Patients' records were rated for the frequency, duration, and complexity of distinct affective states. Very rapid mood fluctuations were absent among bipolar patients in 1960 but were evident in 1975 and 1985. In each year, bipolar patients displayed more frequent, complex, and mixed episodes than did unipolar patients. The results suggest that more frequent episodes occur among bipolar than unipolar patients and that very rapid switch processes have become more widespread for some bipolar patients.