Schizophrenia, alcohol abuse, and violent behavior: a 26-year followup study of an unselected birth cohort.

It has been suggested that schizophrenia and alcoholism are associated with violent behavior. But so far there are no published studies from unselected cohorts quantifying the actual risk associated with schizophrenia both with and without comorbid alcoholism. In this study, an unselected birth cohort (n = 11,017) was prospectively followed to the age of 26, and data on psychiatric disorders and crimes were collected from national registers. The odds ratios for violent offenses and recidivism were calculated for each diagnostic group. Men who abused alcohol and were diagnosed with schizophrenia were 25.2 (95% confidence interval (CI) 6.1-97.5) times more likely to commit violent crimes than mentally healthy men. The risk for nonalcoholic patients with schizophrenia was 3.6 (95% CI 0.9-12.3) and for other psychoses, 7.7 (95% CI 2.2-23.9). None of the patients with schizophrenia who did not abuse alcohol were recidivists (> 2 offenses), but the risk for committing more crimes among alcoholic subjects with schizophrenia was 9.5-fold (95% CI 2.7-30.0). This study suggests that to prevent the crimes being committed by people with schizophrenia, it is important that clinicians watch for comorbid alcohol abuse.