Are behavioral problems in childhood and adolescence associated with bipolar disorder in early adulthood?

Several recent studies have found an association between conduct problems and bipolar disorder in adolescents. However, prospective studies are rare and most do not apply multivariable analysis strategies to control for important variables (e.g. socio-demographics). The aim of this study was to test the association between certain conduct problems and bipolar disorders. The sample consisted of 591 adolescents (male and female) representative for 2,600 persons from the Canton of Zurich in Switzerland. Data were prospectively collected through an interviewing procedure, with the first screening taking place at the age of 19-20. The incidence rate was computed using sampling weights, and risk factors of bipolar II disorder were estimated using a multivariable logistic regression model. The 9-year incidence rate of bipolar II disorder in the canton of Zurich was 8.4% (n = 65). Adolescents and children showing behavior such as repeated running away from home and physical fighting were 2.6-3.5 times more likely to experience a bipolar II disorder than those with no indication of conduct problems. Sensitivity analysis showed that the conduct problems were not the result of low socio-economic status.