Empirical typology of bipolar I mood episodes

Much remains unknown about the phenomenology of bipolar I disorder.

To determine the type of bipolar I mood episodes that occur over time, and their relative frequency.

A total of 219 individuals with Research Diagnostic Criteria bipolar I disorder were prospectively followed for up to 25 years (median 20 years). Psychopathology was assessed with the Longitudinal Interval Follow-up Evaluation.

Overall, 1208 mood episodes were prospectively observed. The episodes were empirically classified as follows: major depression, 30.9% (n = 373); minor depression, 13.0% (n = 157); mania, 20.4% (n = 246); hypomania, 10.4% (n = 126); cycling, 17.3% (n = 210); cycling plus mixed state, 7.8% (n = 94); and mixed, 0.2% (n = 2).

Cycling episodes constituted 25% of all episodes. Work groups revising ICD-10 and DSM-IV should add a category for bipolar I cycling episode.