By Jared Keller
Among the many questions asked after every mass shooting: What, if anything, is the connection between mental illness and violence? It’s a link that’s reinforced regularly by the national news media: A 2016 John Hopkins University analysis found that more than a third of all news stories about mental-health conditions over the last two decades tied mental illness to violent crime.
A new study published in JAMA Psychiatry dispels that relationship. Study authors Jeffrey Swanson and Charles Belden found that, not only is the connection shoddy—the 44-plus million American adults with a mental illness account for between 3 and 5 percent of violent crimes—but in fact those who have a mental illness are more likely to be the victim of a violent crime. Further, one-quarter of all mentally ill Americans are the victim of a violent crime per year, a figure that’s well above the existing rates of violent victimization across the United States.
How then to explain the previously reported link between mental illness and violence? Swanson and Belden argue that, in past research, methodology regarding the relationship between mental health and crime were subject to limited sample sizes of a few thousand individuals. Swanson and Belden’s study, by contrast, incorporates the largest sample size yet, using data from a cohort of more than two million individuals in Denmark, tracked across several years. Their research found that the presence of mental illness tends to increase a subject’s long-term risk of enduring violent crime, a trend that they say “affects people with disorders across the diagnostic spectrum, including those with substance use and personality disorders.”