Violent crimes rates are no higher for mentally ill people with substance abuse than for others who abuse drugs and alcohol, The Guardian reported Sept. 6.

Researchers in Sweden and the United Kingdom reviewed crime-registry data for 3,700 patients with bipolar disorder and 8,000 patients with schizophrenia over a 30-year period and compared results with the general population. Crime rates were six to seven times higher for patients with mental illness and substance abuse than for the population overall, but no higher than those for people with substance abuse who had no mental-health problems.

In addition, when drugs and alcohol were removed from the equation, violent crime was only marginally higher among mentally-ill patients than people in the general population.

“The relationship between violent crime and serious mental illness can be explained by alcohol and substance abuse,” said Dr. Seena Fazel, M.D., forensic psychiatrist and senior lecturer at the University of Oxford and lead author of the research. “It's probably more dangerous walking outside a pub on a late night than walking outside a hospital where patients have been released.”

The findings appear in the September 2010 issue of Archives of General Psychiatry and the May 20, 2009 issue of the Journal of the American Medical Association.