A new study finds that the severe mental disorder schizophrenia only marginally increases the risk of committing violent crime.

Rather, the overrepresentation of individuals with schizophrenia in violent crime is almost entirely attributable to concurrent substance abuse.

The new study, presented in the scientific journal JAMA, is the largest in this field to date. In it, researchers compared the rate of violent crime in over 8,000 people diagnosed with schizophrenia between 1973 and 2006, and a control group of 80,000 people from the general population of Sweden.

Twenty-eight percent of those with schizophrenia and co-occurring substance abuse were convicted of violent crime, compared to eight percent of those with schizophrenia and no substance abuse, and five percent of the general population.

“Hence, the idea that people with schizophrenia are generally more violent than those without is not true,” says Dr Niklas Långström, one of the researchers behind the study.

“People with schizophrenia but no co-occurring substance abuse are insignificantly more violent than people in general.”

Dr Långström hopes that the results could help alleviate fears about mental illness.

“The stigmatization of the mentally ill increases their alienation and makes people less likely to seek the help they need from mental health services,” he says.

“Our results demonstrate once again the importance of preventing, discovering and treating substance misuse in efforts to reduce violent crime.”

Source: Karolinska Institutet