title: A comprehensive review and model of putative prodromal features of bipolar affective disorder.
abstract: BACKGROUND
  Identifying prodromal features that predate the onset of bipolar disorder (BD) may enable the prevention of BD and aid early intervention. This review addresses two key questions: Is there a bipolar prodrome? And, if there is, what are its characteristic features?
  
  
  METHODS
  A comprehensive search of databases (PubMed, Medline, EMBASE and PsycINFO) supplemented by hand searches was used to identify studies of symptoms preceding the onset of BD.
  
  
  RESULTS
  Fifty-nine studies were identified, of which 14 met inclusion criteria. Symptoms can predate the onset of BD by months to years and can be categorized as attenuated forms of BD symptoms, general symptoms common to a range of mental disorders, and personality traits, particularly cyclothymia. Two studies provided sufficient data to enable sensitivity and specificity to be calculated. Specificity of several of the features was high (>90%) but sensitivity was generally low (all <60%). We propose a model based on the findings in the studies reviewed to illustrate the potential trajectory to BD and the points at which it may be possible to intervene.
  
  
  CONCLUSIONS
  Clinical features preceding the onset of BD can be identified. However, conclusions about whether there is a distinct prodrome to BD are restricted by the limitations of current evidence. The high specificity of some features suggests they may be useful in clinical practice. Large-scale longitudinal studies are needed to validate these features and characterize their specificity and sensitivity in independent samples.
authors.affiliation: Psychiatric Imaging Group, MRC Clinical Sciences Centre, Imperial College Hammersmith Campus, London, UK. oliver.howes@kcl.ac.uk
authors.forename: O D
authors.initials: OD
authors.lastname: Howes
authors.forename: S
authors.initials: S
authors.lastname: Lim
authors.forename: G
authors.initials: G
authors.lastname: Theologos
authors.forename: A R
authors.initials: AR
authors.lastname: Yung
authors.forename: G M
authors.initials: GM
authors.lastname: Goodwin
authors.forename: P
authors.initials: P
authors.lastname: McGuire
mesh_terms: D001714:Bipolar Disorder / Q000175:diagnosis / Q000523:psychology*; D018450:Disease Progression; D042241:Early Diagnosis; D006801:Humans; D008960:Models, Psychological; D012307:Risk Factors; D012680:Sensitivity and Specificity