title: Polarity at illness onset in bipolar I disorder and clinical course of illness.
abstract: OBJECTIVE
  Studies have suggested that episode polarity at illness onset in bipolar disorder may be predictive of some aspects of lifetime clinical characteristics. We here examine this possibility in a large, well-characterized sample of patients with bipolar I disorder.
  
  
  METHODS
  We assessed polarity at onset in patients with bipolar I disorder (N = 553) recruited as part of our ongoing studies of affective disorders. Lifetime clinical characteristics of illness were compared in patients who had a depressive episode at first illness onset (n = 343) and patients who had a manic episode at first illness onset (n = 210).
  
  
  RESULTS
  Several lifetime clinical features differed between patients according to the polarity of their onset episode of illness. A logistic regression analysis showed that the lifetime clinical features significantly associated with a depressive episode at illness onset in our sample were: an earlier age at illness onset; a predominantly depressive polarity during the lifetime; more frequent and more severe depressive episodes; and less prominent lifetime psychotic features.
  
  
  CONCLUSIONS
  Knowledge of pole of onset may help the clinician in providing prognostic information and management advice to an individual with bipolar disorder.
authors.affiliation: Department of Psychological Medicine, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Liz
authors.initials: L
authors.lastname: Forty
authors.forename: Lisa
authors.initials: L
authors.lastname: Jones
authors.forename: Ian
authors.initials: I
authors.lastname: Jones
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Smith
authors.forename: Sian
authors.initials: S
authors.lastname: Caesar
authors.forename: Christine
authors.initials: C
authors.lastname: Fraser
authors.forename: Katherine
authors.initials: K
authors.lastname: Gordon-Smith
authors.forename: Sally
authors.initials: S
authors.lastname: Hyde
authors.forename: Nick
authors.initials: N
authors.lastname: Craddock
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001714:Bipolar Disorder / Q000145:classification* / Q000503:physiopathology* / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D003866:Depressive Disorder / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D018709:Statistics, Nonparametric; D055815:Young Adult