title: The incidence and onset-age of hospitalized bipolar affective disorder in Finland.
abstract: BACKGROUND
  Some studies have indicated that there are wide variations on incidence and prevalence of bipolar disorder in specific populations.
  
  
  METHODS
  The occurrence of bipolar affective disorder and the age at onset was studied in both genders among the hospitalized Finnish population.
  
  
  RESULTS
  The annual rate of all hospitalized patients with bipolar disorder was 0.03%. Of these, 2% were under 20 years, 14% under 30 years, 61% under 50 years and 81% under 60 years of age. The 1-year incidence was highest in the age group 50-59 years in males and 40-49 years in females.
  
  
  CONCLUSIONS
  The low prevalence and incidence of bipolar disorder in Finland may be due to late onset-age.
  
  
  CONCLUSIONS
  The study is based on hospital-treated bipolar disorder patients.
  
  
  CONCLUSIONS
  We have presented previously unreported differences between the age of onset of bipolar disorder in Finland compared with other countries.
authors.affiliation: Department of Psychiatry, University of Oulu, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Räsänen
authors.forename: J
authors.initials: J
authors.lastname: Tiihonen
authors.forename: H
authors.initials: H
authors.lastname: Hakko
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000453:epidemiology* / Q000523:psychology / Q000534:rehabilitation*; D002648:Child; D005260:Female; D005387:Finland / Q000453:epidemiology; D006760:Hospitalization; D006778:Hospitals, Psychiatric; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D017678:Sex Distribution