Early age at onset as a risk factor for poor outcome of bipolar disorder

The primary aim of our study was to investigate the effect of the age at onset (AAO) of Bipolar Disorder (BP) on the clinical course of the illness. We studied 320 subjects with a diagnosis of BP I or BP II who had been previously recruited for a genetic research protocol. All subjects gave their informed consent to participate in the study. Each subject was interviewed using the SCID I. The main clinical variables were compared between subjects with early (/=18 years) age at onset of BP (chi square tests and t-tests for independent samples). In addition, a logistic regression analysis was applied to the variables that were significantly related to earlier onset of BP in the exploratory analyses. We found a significantly earlier AAO in subjects with anxiety disorders (t=2.44, P=0.015) and rapid cycling course (t=3.16, P=0.002). When we compared a number of clinical characteristics between early and later onset of BP, subjects with early AAO had more frequent suicidal ideation/attempts (chi(2)=12.12, P=0.002), Axis I comorbidity (chi(2)=8.12, P=0.004), substance use disorders (chi(2)=5.45, P=0.019) and rapid cycling course (chi(2)=9.87, P=0.002). The Odds Ratios associated with these variables were: 1.407 (suicide ideation), 1.646 (Axis I comorbidity), 1.468 (substance abuse), and 2.082 (rapid cycling course). Overall, these results suggest a role of early AAO as a significant predictor of poor outcome in BP and, if replicated, they may have important clinical implications.