Polarity sequence, depression, and chronicity in bipolar I disorder

Five independent studies show that polarity sequence is associated with pro gnosis in bipolar I disorder. Episodes in which major depression precedes m ania (DMI) lead to higher morbidity than biphasic episodes which begin with mania (MDI). However, little is known about the prognostic significance of polarity sequence for long-term outcome. This study examined polarity sequ ence across multiple episodes among 165 bipolar I patients followed prospec tively for up to 15 years as part of the NIMH Collaborative Study of Depres sion. Episodes beginning with major depression were significantly longer th an those beginning with mania for the first three prospectively observed ep isodes when pooling all episode types-monophasic, biphasic, and polyphasic. Furthermore, affective polarity at onset for the first prospectively obser ved episode was associated with polarity at onset for the remaining three e pisodes. Patients whose first prospectively observed episode began with dep ression had higher overall morbidity during the entire follow-up period.