Depression with DSM-IV atypical features: a marker for bipolar II disorder

The aim of the study was to find the prevalence of atypical features in bipolar II depression versus unipolar depression. Five hundred and fifty seven unipolar and bipolar II depressed outpatients were interviewed with the Structured Clinical Interview for DSM-IV. the Montgomery Asberg Depression Rating Scale, and the Global Assessment of Functioning Scale. DSM-IV atypical features were significantly more common in bipolar II patients than in unipolar patients (45.4% vs 25.4%, odds ratio 2.4). As the diagnosis of bipolar II disorder is often based on diagnosis of past hypomania, which may not be very reliable, depression with atypical features may point to bipolar II disorder diagnosis.