Two articles published today in Mayo Clinic Proceedings question the effectiveness of trying to prevent mass shootings by keeping guns away from "mentally ill individuals." The longer essay, by forensic psychiatrists Ryan Chaloner Winton Hall and Susan Hatters Friedman, notes that people on both sides of the gun control debate tend to agree that restricting the rights of people diagnosed with mental disorders is a sensible response to massacres like those in Tucson, Aurora, and Newtown. Yet it is hard to see how such crimes could be prevented by improving the background check system that aims to enforce the federal ban on selling guns to people who are involuntarily committed or adjudicated as "mentally defective":

Even if the Brady law is fully implemented and expanded, questions remain regarding whether it would have been able to prevent school shootings like the ones that have occurred. Many times, individuals already own guns by the time they would meet criteria to be added to this list, and the waiting period does not seem to be a deterrent or obstacle because most school-based or mass shootings are planned in advance. Furthermore, shootings such as those at Columbine High School in Littleton, Colorado, and Sandy Hook Elementary School in Newtown, Connecticut, would not have been prevented because the individuals obtained the guns from family and friends.

Mass shooters generally do not have psychiatric histories that would disqualify them from gun ownership under current law, meaning they would not be stymied by background checks even if the records were complete and they had no alternative way to obtain firearms. But Hall and Friedman argue that expanding the category of people disqualified by a psychiatric assessment would undermine civil liberties while doing little to improve public safety. New York's SAFE Act, for example, requires mental health professionals to report patients they believe may harm themselves or others so their guns can be confiscated. This year Florida's legislature considered a bill that would have required "health care providers with direct knowledge of an individual's mental health status and propensity for violence to provide identifying information to law enforcement for inclusion in the automated database of persons prohibited from purchasing a firearm." The bill asserted that "prohibiting persons who have mental illness from having access to firearms is an important state interest." National Rifle Association Executive Vice President Wayne LaPierre, who after the Newtown massacre demanded "an active national database of the mentally ill," seems to agree.

As I noted at the time, that would be a pretty big database, since survey results indicate that nearly half of all Americans will qualify for a psychiatric diagnosis at some point in their lives. Maybe LaPierre has in mind an especially dangerous subset of the mentally ill. But which one? "The condition that may most commonly come to mind when the public refers to mental illness and guns is schizophrenia," write Hall and Friedman, but data from the National Comorbidity Survey indicate that "the mental illnesses actually most likely to result in increased threatening behavior with a gun are bipolar disorder type 1…and drug dependence…both potentially fluctuating, unpredictable states." In a major study by the MacArthur Foundation, "a diagnosis of major mental disorder was correlated with a lower violence risk."

A companion editorial by Mayo Clinic psychiatrist J. Michael Bostwick notes that a Swedish study found that "individuals discharged from psychiatric hospitals with severe psychotic or affective diagnoses did have 3.8 times the odds of committing [violent] crimes than did their non–mentally ill countrymen," although "their number relative to the general populace was so low that only 1 in 20 violent crimes could be attributed to them." Similarly, American studies have "estimated a 2- to 4-fold increase in the risk of violence by individuals with schizophrenia but only a 3% to 5% population-attributable risk."

Both essays note that even if people who receive certain diagnoses are more likely to commit acts of violence than the general population, the vast majority of them do not. According to the American Psychiatric Association, "96% of people with serious mental illnesses never act violently." Any attempt to prevent all of them from owning guns would be highly inefficient as well as unfair (and unconstitutional, given the weakness of the public safety rationale). And as both essays emphasize, psychiatrists not only admit they are bad at predicting which individuals will turn violent; they insist upon it, lest they be held liable for their failure to prevent future crimes. Hall and Friedman quote a 1983 decision in which the U.S. Supreme Court observed that "neither petitioner nor the APA suggests that psychiatrists are always wrong with respect to future dangerousness, only most of the time." Research suggests even that assessment is excessively generous.

Bostwick says he was inclined to disagree with Hall and Friedman's assessment when he was asked to comment on their article but was persuaded that the mass shootings they discuss "were not and could not have been prevented by more restrictive gun legislation." He also agrees that "a diagnosis of mental illness…does not justify stripping Second Amendment rights from all who carry such a diagnosis, most of whom will never commit violent acts toward others." Bostwick urges his colleagues to reject "the fallacy that they can predict gun-related tragedies" as well as "the passive and simplistic dogma that guns are evil and should simply go away." He adds:

[Hall and Friedman] have resoundingly dispelled any lingering belief I might have entertained that laws designed to keep firearms from the mentally ill can prevent horrific school shootings such as those in Arizona, Colorado, and Connecticut or killings on military bases such as the recent Washington Naval Yard massacre. They have convinced me that firearms are here to stay and that wishing them away serves neither my patients nor myself.

More on the limitations of the mental health solution to gun violence here and here.

[Thanks to Mark Sletten for the tip.]