Mental disorders associated with driving under the influence of alcohol and/or drugs: a register-based study.

BACKGROUND/AIMS Mental disorders are associated with driving under the influence (DUI), but the evidence is scarce and mostly focused on a limited group of repeat drunken drivers. Thus, the aim of this study was to examine which mental disorders were risk factors for DUI of alcohol only (DUIA), of illicit drugs (DUID) or of alcohol and psychoactive prescription drugs (DUIAP), and whether and how the risk differs over time. METHODS A register-based case-control study was conducted. Cases (n=44,188) suspected by the police of DUI during 1997-2007 and controls (n=45,148) were drawn from the general Finnish population. The official national register of hospital treatments was the data source for mental disorders. The effects of mental disorders on DUI were estimated using logistic regression analysis. RESULTS Substance use disorders increased the risk of DUI overall. Childhood- and adolescence-onset disorders were a strong predictor of DUID, and bipolar and depressive disorders predicted DUIAP. The risk was highest soon after hospital admission with a psychiatric diagnosis, but it decreased over time. CONCLUSIONS Actions to prevent DUI should be developed and implemented during the treatment of mental disorders.