Age at onset of bipolar II depressive mixed state

Depressive mixed state (DMS) (a major depressive episode [MDE] with some concurrent hypomanic symptoms) is understudied. The aims of the study were to find if the prevalence of DMS, and its clinical correlates, in bipolar II depressed outpatients changed according to bipolar II age at onset. A consecutive sample of 92 bipolar II MDE outpatients were interviewed with the Structured Clinical Interview for DSM-IV. DMS was defined as an MDE with two or more concurrent hypomanic symptoms (DMS2). Prevalence of DMS2 in bipolar II with onset after 30 and 40 years was significantly lower than prevalence in bipolar II with onset before 31 and 41 years. There was a significant negative association between DMS2 and age at onset. There were no significantly different clinical correlates between DMS2 in bipolar II with onset after 30 and before 31 years. Limitations of the study include use of a single interviewer, non-blind assessment, cross-sectional design and bipolar II diagnosis based on history. DMS2 was more likely in bipolar II with a younger age at onset. Different bipolar II ages at onset did not have an effect on DMS2 clinical correlates.