Early-onset versus late-onset bipolar II chronic depression

Age at onset is an important dimension in the classification of mood disorders. Recent findings on early-onset (EO) versus late-onset (LO) unipolar chronic depressions support this subtyping. The aim of the present study was to determine clinical differences between EO and LO bipolar II chronic depression and to support this subtyping also in bipolar II. Eighty-seven consecutive bipolar II chronic depression outpatients were interviewed with the Structured Clinical Interview for DSM-IV, the Montgomery Asberg Depression Rating Scale, and the Global Assessment of Functioning scale. EO cut-offs were 21 and 23 years of age. Variables, studied with linear and logistic regression, were age, gender, age at onset, illness duration, recurrences, atypical, melancholic, and psychotic features, axis I comorbidity, and severity. Lower age at onset was significantly associated with lower age, longer illness duration, less psychosis, less severity, more atypical features, and more axis I comorbidity. Results support the subtyping of bipolar II chronic depression in EO and LO on the basis of different clinical features.