Gender Differences in Incidence and Age at Onset of Mania and Bipolar Disorder Over a 35-Year Period in Camberwell, England

OBJECTIVE: Despite clear gender differences in the symptoms and course of bipolar affective disorder, studies investigating age at onset by gender have yielded inconsistent results. The authors investigated gender differences in age at onset and incidence of first-episode mania and bipolar disorder in an epidemiological catchment area in southeast London over a 35-year period. METHOD: All adult cases of first-episode psychosis, mania, or hypomania presenting to services in Camberwell, southeast London (1965-1999), were identified. Computerized diagnoses for these cases were generated by using the Operational Checklist for Psychotic Disorders program. Incidence rates and rate ratios of DSM-IV bipolar I disorder, first manic episode, by gender and age (10-year age-at-onset categories) were calculated. Differences in age at onset of first-episode mania and bipolar disorder by gender were examined by using univariate and multivariate analyses. RESULTS: Men had a significantly earlier onset of first-episode mania and bipolar disorder, with childhood antisocial behavior also being significantly associated, after multivariate analysis. Women had higher incidence rates of bipolar I disorder throughout adult life, except for early life (ages 16-25 years), although gender differences in individual age bands did not reach statistical significance. CONCLUSIONS: Men appear to have an earlier onset of mania and bipolar disorder than women. The association of male gender and childhood antisocial behavior with early-onset bipolar disorder raised the possibility of the existence of an early-onset subgroup.