Atypical bipolar II depression compared with atypical unipolar depression and nonatypical bipolar II depression.

Aim of the study was to find out whether atypical bipolar II depression was distinct from both atypical unipolar depression and nonatypical bipolar II depression. Seventy-nine consecutive atypical bipolar II depressed outpatients were compared with 42 consecutive atypical unipolar depressed outpatients and with 53 consecutive nonatypical bipolar II depressed outpatients. Among the variables studied (age at intake, age at onset, female gender, duration of illness, psychosis, comorbidity, chronicity, recurrences, severity), age at intake and onset were significantly lower in the atypical bipolar II group than in the other groups. The other variables, apart from psychosis, were not significantly different. Findings suggest that atypical bipolar II depression may have an age at onset different from that of atypical unipolar depression and nonatypical bipolar II depression. As different ages at onset may identify distinct subtypes of depression, this finding might suggest that atypical bipolar II depression may be distinct from both atypical unipolar depression and nonatypical bipolar II depression.