It's rare that people with mental illness have hallucinations and delusions before they commit violent crimes, researchers say.
"High-profile mass shootings capture public attention and increase vigilance of people with mental illness. But our findings clearly show that psychosis rarely leads directly to violence," said study lead authour Jennifer Skeem, associate dean of research at University of California, Berkeley's School of Social Welfare.
How the study was done
Researchers analysed 305 violent incidents committed by high-risk psychiatric patients in the United States. They found that only 12 percent of the incidents were preceded by hallucinations and delusions, collectively referred to as psychosis.
The study was recently published online in the journal Clinical Psychological Science.
Numerous studies have found that violence is often associated with anger, access to guns and substance abuse, but this is the first to examine how often psychosis occurs before violent crimes, the study authours said.
The findings challenge the widespread belief that many acts of violence are due to mental illness, the investigators added.
"None of this detracts from the message that people with mental illness need access to psychiatric services," Skeem said in a university news release. "But it's important to remember that risk factors for violence - such as substance abuse, childhood maltreatment, neighbourhood disadvantage -- are mostly shared by people with and without mental illness, and that's what we should be focused on if maximizing public safety is our goal."
A study published earlier this year in the American Journal of Public Health found that fewer than 5 percent of the 120,000 gun murders in the United States between 2001 and 2010 were committed by people with a mental illness diagnosis, the researchers pointed out. That study also said that people with mental illness are far more likely to be victims of violent crime than people in the general population.
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