Heterogeneity of the Risk of Suicidal Behavior in Bipolar-Spectrum Disorders

The distribution of suicides & suicide attempts in 539 subjects from 78 families of probands with major affective disorders, all responders to lithium prophylaxis, was studied. A Cox proportional hazard regression model was used to assess the contribution of several independent variables to the risk of affective disorders, bipolar disorder, & suicidal behaviour. The lifetime prevalence of bipolar disorder was significantly greater among first-degree relatives of suicide than non-suicide probands & the prevalence of bipolar disorder in families was associated with an increased risk of developing mood disorder & subsequently dying by or attempting suicide. Results suggest that partially overlapping sets of genetic factors may underlie bipolar disorder & suicide. (51 refs.)