title: Gender differences in incidence and age at onset of mania and bipolar disorder over a 35-year period in Camberwell, England.
abstract: 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.
  
  
  METHODS
  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.
authors.affiliation: Section of General Psychiatry, Division of Psychological Medicine, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK. N.Kennedy@iop.kcl.ac.uk
authors.forename: Noel
authors.initials: N
authors.lastname: Kennedy
authors.forename: Jane
authors.initials: J
authors.lastname: Boydell
authors.forename: Sri
authors.initials: S
authors.lastname: Kalidindi
authors.forename: Paul
authors.initials: P
authors.lastname: Fearon
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000987:Antisocial Personality Disorder / Q000175:diagnosis / Q000453:epidemiology; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology*; D002391:Catchment Area, Health / Q000706:statistics & numerical data; D002648:Child; D002653:Child Behavior Disorders / Q000175:diagnosis / Q000453:epidemiology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012737:Sex Factors