Early risk factors for criminal offending in schizophrenia: a 35-year longitudinal cohort study.

BACKGROUND: Recent evidence suggests that factors predicting offending among individuals with no mental disorder may also predict offending among individuals with schizophrenia.

AIMS: The aims of the study were (1) to explore the prevalence of risk factors for criminal offending reported at age 18 among males later diagnosed with schizophrenia, (2) to explore the associations between risk factors reported at age 18 and lifetime criminal offending, (3) to predict lifetime serious violent offending based on risk factors reported at age 18, and (4) to compare the findings with those in males with no later diagnosis of schizophrenia.

METHODS: The study was a prospective, longitudinal study of a birth cohort followed up through registers after 35 years. The cohort consisted of 49,398 males conscripted into the Swedish Army in 1969-1970, of whom 377 were later diagnosed with schizophrenia.

RESULTS: Among the subjects later diagnosed with schizophrenia, strong associations were found between four of the items reported at age 18 and lifetime criminal offending: (1) low marks for conduct in school, (2) contact with the police or child care authorities, (3) crowded living conditions, and (4) arrest for public drinking. Three of these four risk factors were found to double the risk of offending among males with no later diagnosis of schizophrenia.

CONCLUSIONS: Criminality in individuals with schizophrenia may at least partly be understood as a phenomenon similar to criminality in individuals in the general population.