A survey of 34,653 people by researchers at the University of North Carolina looked into the links between mental health and violence and also at some of the other factors linked to violence. Participants in the study filled out questionnaires between 2001 and 2003 and three years later they were asked whether they had commited any acts of violence. Those people with severe mental illness but who did not take drugs were no more likely than anyone else to be violent. However, those people with alcohol and/or drugs problems and severe mental illness were three times more likely to have been violent. Even so the combination of severe mental illness and substance abuse was only ninth out of the top ten predictors of violence behind factors such as youth, a history of juvenile detention, violence and physical abuse, criminal parents and unemployment. People with a prior history of violence, substance abuse and severe mental illness were nearly ten times as violent as those with mental illness only.
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