Violence of young criminals predicts schizophrenia: a 9-year register-based followup of 15- to 19-year-old criminals.

Violent and aggressive behavior in preschizophrenia adolescents has been described in several studies. Our aim was to investigate the extent to which violent conviction in late adolescence predicted later schizophrenia in a cohort of young criminals. We performed a 9-year register-based followup of a complete national cohort of young convicted criminals. A total of 780, 15- to 19-year-old subjects identified in 1992 were followed up in 2001 with register linkage of the Danish Psychiatric Central Register, the Danish National Criminal Register, and the Danish National Cause of Death Register. Analyses with Cox regression were performed to identify predictors of later schizophrenia. We found at followup that 3.3 percent of the cohort had been diagnosed with schizophrenia and 4.5 percent with any psychosis. Conviction of violence in late adolescence was significantly associated (odds ratio = 4.59 [95% confidence interval (1.54; 13.74)]) with future diagnosis of schizophrenia. Violent behavior can thus be seen as part of the preschizophrenia phase of young criminals.