Admixture analysis of age at onset in bipolar disorder

The aim of this study was to identify whether age at onset (MO) identifies Bipolar Disorder (BD) subtypes. and to test whether the subgroups were confirmed by different clinical profiles. Admixture analysis was applied to determine a model that best fit the observed distribution of MO in 964 BD patients. Three distributions of MO were identified, and age means were 16.1 (S.D. 4.2), 25.4 (S.D. 2.5) and 32.2 (S.D. 9.5) years. A significant increased rate of suicide attempts, Bipolar I (BD I) caseness, and depressive onset was observed in the early-onset group when compared to those with later-onset by means of chi(2). Findings from extant studies and our results are remarkably consistent in showing that BD can be subdivided into three groups based on MO distributions, and that early-onset is associated with higher rates of suicide attempts. (C) 2009 Elsevier Ireland Ltd. All rights reserved.