The National Rifle Association and other gun rights groups have blamed inadequate care of the mentally ill for mass shootings. Such claims not only distract from the core problem—easy access to firearms—but stigmatize the mentally ill as being prone to violent behavior, says Paul S. Appelbaum, a professor of psychiatry, medicine and law at Columbia University Medical Center. Appelbaum argued in JAMA Psychiatry last year that identifying people with mental illness as a primary cause of violence “is misleading, counterproductive and just plain mean.”

Q: Are people with mental illnesses more likely than others to commit violence?
A: The bulk of data suggests that mental illness appears to elevate the rate of violent behavior somewhat. However, only about 4% of violent behavior in the United States is attributable to mental illness. We have the most data about people who have schizophrenia and other psychotic disorders; they may commit violence two to four times more frequently than people in the general population. And studies suggest that other disorders, such as depression, may elevate rates of violence to an even greater extent. Those who have mental illnesses are much more likely to be victims of violence, not perpetrators. Indeed, suicide is much more of a problem among people with mental illness than is aggression toward others.

Q: Didn’t the perpetrators of several recent mass killings have histories of mental illness or erratic behavior?
A: Many of the most highly publicized of those shootings have involved people, usually young men, with histories of mental disorders that went untreated. However, violence occurs for many reasons, including feelings of anger, jealousy and humiliation in family relationships or in the workplace. Even when someone who has been diagnosed with mental illness commits violence, the connection is not always clear cut. The Newtown shootings are an example of just how quickly we jump to the assumption that mental illness lies at the core of mass killings. We have no evidence that the perpetrator was ever diagnosed with any mental condition other than Asperger’s syndrome, which we know is not associated with higher rates of violence. We ought not to assume that a killer is mentally ill until we have clear evidence of the fact.

Q: What’s known about the biology of violence?
A: There’s conflicting data about testosterone and its relationship to violence. Boys become more violent in the postpubertal period when their blood levels of testosterone rise. Yet violent men don’t necessarily have higher than average overall levels of testosterone. Some evidence links low serotonin levels and violence, but there, too, the studies aren’t consistent. Neuroimaging findings suggest that some violent offenders, particularly those with psychopathy—who display callous, antisocial behavior—have reduced brain activity in regions of the frontal lobe that are associated with planning, forethought and impulse control, and in parts of the brain associated with emotional regulation, including the amygdala. But the studies were small and it’s not clear how much we can generalize. If there’s anything that appears to be true, it’s that there is no one path to violent behavior.

Q: You’ve been critical of a New York State law requiring health care workers to notify government authorities if they think a patient may harm him- or herself or others. Why?
A: Mental health professionals have a responsibility to intervene to prevent violence, but that doesn’t necessarily mean reporting the patient to a state-operated database. The most effective interventions are likely to be those that take place within the context of a treatment relationship. My concern about the New York law is that it once again puts the focus exclusively on people with mental illness, as if they were the problem and if we only keep guns away from them, there will be no more violence to worry about. The law is also likely to be counterproductive. The very people we would most want to have in treatment may be exactly those who will be dissuaded from getting it if they’re aware they will be reported to a state database.

Q: Are Americans more violent than others?
A: We do appear to be more seriously violent than our peer countries in the developed world. Our murder rate is around three gun homicides per 100,000 Americans each year. That’s more than three times what it is in Canada and most of Europe. There are certainly reasons to suspect that the easy availability of guns helps drive our murder rate to where it is.

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