title: [Early onset bipolar disorder: validation from admixture analyses and biomarkers].
abstract: OBJECTIVE
  Bipolar affective disorder (BD) is a multifactorial disorder with heterogeneous clinical presentations, in particular according to age at onset (AAO). The relevance of such an indicator has been discussed as a potential specifier in future nosographical classification.
  
  
  METHODS
  We summarize available evidence of admixture analyses and biomarkers in early onset BD.
  
  
  RESULTS
  Numerous clinical arguments have led us to conclude that the early onset BD subgroup is clinically homogeneous, with particular, recurrent, and severe characteristics.Eight admixture studies have demonstrated the existence of 3 subgroups of patients with BD according to AAO (early, intermediate, and late AAO), with 2 cut-off points of 21 (21.33) [SD 1.41]) and 35 years (34.67 [SD 5.52]). Differential clinical features and outcome measures characterize the early onset subgroup: higher rate of suicide attempts, rapid cycling, alcohol and drugs misuse, psychotic symptoms, and comorbid anxiety disorders. This may partially explain the delayed diagnosis and late initiation of mood stabilizers. Genetic, biological, imaging, and cognitive arguments may be considered as potential markers in providing external validity of the existence of this early onset subgroup. Implementation of AAO in the algorithms of treatment may be discussed, although the level of proof for focused medication strategies remains to be consolidated.
  
  
  CONCLUSIONS
  Given the high frequency (44.80%) of early onset BD, awareness of clinicians should be stimulated to provide an early and accurate detection, preventive strategies, and possibly specific treatments.The forthcoming DSM-5 should include AAO as a specifier, given its relevance for course and outcome.
authors.affiliation: Hôpital H. Mondor-A. Chenevier, Pôle de psychiatrie, et Fondation Fonda Mental, Créteil, France.
authors.forename: Pierre Alexis
authors.initials: PA
authors.lastname: Geoffroy
authors.forename: Bruno
authors.initials: B
authors.lastname: Etain
authors.forename: Stéphane
authors.initials: S
authors.lastname: Jamain
authors.forename: Frank
authors.initials: F
authors.lastname: Bellivier
authors.forename: Marion
authors.initials: M
authors.lastname: Leboyer
mesh_terms: D017668:Age of Onset; D001008:Anxiety Disorders / Q000453:epidemiology / Q000523:psychology; D015415:Biomarkers / Q000378:metabolism; D001714:Bipolar Disorder / Q000453:epidemiology / Q000378:metabolism / Q000523:psychology*; D015897:Comorbidity; D006801:Humans; D019966:Substance-Related Disorders / Q000453:epidemiology / Q000523:psychology; D013406:Suicide, Attempted / Q000523:psychology / Q000706:statistics & numerical data
chemical_list: D015415:Biomarkers