May 26, 2009

Schizophrenia link to violence very low

[Posted: Sun 24/05/2009 by Joanne McCarthy]

Schizophrenia only very marginally increases the risk of committing violent crime, according to a new Swedish study.

The reason there is an over-representation of people with schizophrenia in violent crime is almost entirely attributable to substance abuse, according to the researchers.

Previous research suggests that people with schizophrenia, a major psychotic disorder, are at higher risk for violent behaviour. However, there has been some uncertainty as to the magnitude of this risk increase and whether it can really be attributed to schizophrenia itself or to other factors.

The new study is the largest in this field to date, comparing the rate of violent crime in over 8,000 people with schizophrenia, and a group of 80,000 people from the general population of Sweden.

Some 28% of those with both schizophrenia and substance abuse were convicted of violent crime, compared to 8% of those with schizophrenia and no substance abuse, and 5% of the general population.

“The idea that people with schizophrenia are generally more violent than those without is not true. People with schizophrenia but no co-occurring substance abuse are insignificantly more violent than people in general,” said Dr Niklas Langstrom of the Karolinska Institutet, one of the researchers behind the study.

It is hoped that the results will help alleviate fears about mental illness.

“The stigmatisation of the mentally ill increases their alienation and makes people less likely to seek the help they need from mental health services. Our results demonstrate once again the importance of preventing, discovering and treating substance misuse in efforts to reduce violent crime,” he said.

The results of the study have been published in the scientific journal JAMA.