title: An increased proportional representation of bipolar disorder in younger depressed patients: analysis of two clinical databases.
abstract: OBJECTIVE
  To pursue the suggested increased incidence of bipolar disorder by examining for a cohort effect in the proportional representation of Bipolar Disorder in two independent clinical samples of depressed patients.
  
  
  METHODS
  Assessment of polarity status was undertaken with some consistency over defined collection periods in two independent samples.
  
  
  RESULTS
  The lifetime proportional rates of bipolar disorder declined with age from some 60% to 30% in both samples.
  
  
  CONCLUSIONS
  The strikingly similar age-related pattern in both samples and the linear trajectory support a cohort effect where the incidence of bipolar disorder may be increasing disproportionately in younger individuals.
authors.affiliation: School of Psychiatry, University of New South Wales; Black Dog Institute, Sydney, Australia. g.parker@unsw.edu.au
authors.forename: Gordon
authors.initials: G
authors.lastname: Parker
authors.forename: Heather
authors.initials: H
authors.lastname: Brotchie
authors.forename: Kathryn
authors.initials: K
authors.lastname: Fletcher
mesh_terms: D000328:Adult; D017677:Age Distribution; D001714:Bipolar Disorder / Q000453:epidemiology*; D015897:Comorbidity; D003866:Depressive Disorder / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged