title: Clinical expression of bipolar disorder type I as a function of age and polarity at onset: convergent findings in samples from France and the United States.
abstract: BACKGROUND
  The clinical presentation, course, and comorbidities of bipolar disorder type I are highly heterogeneous, and this variability remains poorly predictable. Certain onset characteristics (eg, age and polarity at onset) may delineate subgroups differing in clinical expression and outcome.
  
  
  METHODS
  We retrospectively investigated the association between both age and polarity at onset and the clinical characteristics of bipolar I disorder (DSM-IV) in 2 independent adult samples: 480 French patients assessed in 1992-2006 (patients had been recruited from 3 university-affiliated psychiatry departments) and 714 US patients assessed in 1991-2003 (data were extracted from the Bipolar Disorder Phenome Database).
  
  
  RESULTS
  Polarity at onset correlated with subsequent predominance (P < .001). Most patients experienced a depressive onset (57.9% in France vs 71.0% in the United States; P < .001) associated with a higher density of depressive episodes, suicidal behavior, and alcohol misuse. A manic onset was associated with a higher density of manic episodes. Early onset was frequent in both countries (42% in France vs 68% in the United States; P < .001) and was associated with suicidal behavior and cannabis and cocaine/opiate misuse. Sensitivity for the prediction of clinical characteristics was 1%-35% for age at onset and 26%-47% for polarity at onset.
  
  
  CONCLUSIONS
  Onset characteristics are associated with subsequent predominant polarity, suicidal behavior, and substance misuse in bipolar I disorder. These findings may facilitate personalized treatment strategies based on type of onset and may also facilitate early focused strategies for preventing comorbidity. Given the relatively low sensitivity and specificity of these onset characteristics for predicting clinical variables, the relevance of age and polarity at onset as specifiers in nosographical classifications will require further studies. However, polarity at onset may be the more relevant specifier, with further investigation required for age at onset.
authors.affiliation: Institut national de la santé et de la recherche médicale (INSERM), Créteil, France. bruno.etain@inserm.fr
authors.forename: Bruno
authors.initials: B
authors.lastname: Etain
authors.forename: Mohamed
authors.initials: M
authors.lastname: Lajnef
authors.forename: Frank
authors.initials: F
authors.lastname: Bellivier
authors.forename: Flavie
authors.initials: F
authors.lastname: Mathieu
authors.forename: Aurélie
authors.initials: A
authors.lastname: Raust
authors.forename: Barbara
authors.initials: B
authors.lastname: Cochet
authors.forename: Sébastien
authors.initials: S
authors.lastname: Gard
authors.forename: Katia
authors.initials: K
authors.lastname: M'Bailara
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Kahn
authors.forename: Orly
authors.initials: O
authors.lastname: Elgrabli
authors.forename: Renaud
authors.initials: R
authors.lastname: Cohen
authors.forename: Stéphane
authors.initials: S
authors.lastname: Jamain
authors.forename: Eduard
authors.initials: E
authors.lastname: Vieta
authors.forename: Marion
authors.initials: M
authors.lastname: Leboyer
authors.forename: Chantal
authors.initials: C
authors.lastname: Henry
mesh_terms: D000328:Adult; D017668:Age of Onset; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology