Polarity at illness onset in bipolar I disorder and clinical course of illness

• Published in: Bipolar disorders 2009-02, Vol.11 (1), p.82-88
• Main Authors: Forty, Liz, Jones, Lisa, Jones, Ian, Smith, Daniel J, Caesar, Sian, Fraser, Christine, Gordon-Smith, Katherine, Hyde, Sally, Craddock, Nick
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; affective disorder; Age of Onset; bipolar disorder; Bipolar Disorder - classification; Bipolar Disorder - physiopathology; Bipolar Disorder - psychology; Child; Child, Preschool; depression; Depressive Disorder - physiopathology; Depressive Disorder - psychology; Female; Humans; Infant; Logistic Models; Male; mania; Middle Aged; onset polarity; Psychiatric Status Rating Scales; Statistics, Nonparametric; Young Adult
• ISSN: 1398-5647; 1399-5618
• DOI: 10.1111/j.1399-5618.2008.00654.x

Objectives:  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.