Cyclothymic disorder: validating criteria for inclusion in the bipolar affective group.

The authors identified 46 cyclothymic probands from a random pool of 500 psychiatric outpatients and prospectively followed them over a 2-3 year period. They used 50 bipolar patients with a definite history of mania and 50 patients with personality disorders as control groups. Although 66% of the cyclothymic outpatients had previously received the diagnosis of hysteria or sociopathy, their pedigrees were similar to those seen in classical bipolar manic-depressive illness; furthermore, 44% of the cyclothymic group experienced brief hypomanic episodes while taking tricyclic drugs, and 35% developed full-blown hypomanic, manic, or depressive episodes during drug-free follow-up. The authors conclude that these findings provide evidence for a cyclothymic-bipolar spectrum.