When it comes to preventing gun-related violence, President Barack Obama and the National Rifle Association agree on one key priority: Both call for measures aimed at preventing people with mental illnesses from owning firearms.
In the days after a lone gunman massacred 20 schoolchildren in Newtown, Conn., Obama called for an expansion of mental health services and more stringent background checks for gun buyers to screen out those who may pose a danger. The NRA proposed the creation of a national registry of people with mental illnesses to help limit their ability to purchase guns.
But public health and firearms experts assert that focusing on mental illness is unlikely to achieve a significant reduction in gun violence, because the vast majority of shootings are the handiwork of people who do not fit the profile of those deemed dangerous. Moreover, by shifting the debate away from gun control and toward mental health concerns, proponents run the risk of further stigmatizing mental illness, discouraging those who confront it from seeking professional help.
"Gun violence is a mental health issue only to a very small extent and to a much smaller extent than most people assume," said Paul Appelbaum, a psychiatrist and the director of the Columbia University College of Physicians and Surgeons' Division of Law, Ethics and Psychiatry.
"Most gun violence is just not committed by people with mental illness," he said. “Were we somehow to stop violence by anyone with a mental illness -- as unlikely as that outcome might be -- we would be safer, but only a teeny bit safer. As much as these incidents attract everybody's attention and concern, they are a tiny fraction of the people who get killed in this country every year."
Despite the earnest discussion of mental illness that follows seemingly every headline-capturing mass shooting, people with mental illnesses are responsible for no more than 5 percent of all violent acts in the United States, according to research published by the Institute of Medicine in 2005. By contrast, an estimated 20 percent of American adults reported having some form of mental illness in 2011, and 5 percent reported a serious mental illness, according to a survey from the Substance Abuse and Mental Health Services Administration released this month.
Mental illness is the cause of fewer mass shootings than the public perceives, Appelbaum said. "If you look at the lists that are put together of those kinds of events, they are primarily family and workplace violence episodes," he said.
But in the policy arena, public perception functions as effective reality, given the dearth of data. No thorough study exists establishing a connection between mental illnesses and mass shootings, Appelbaum said. Neither does a database of mass shootings that would allow researchers to flesh out a useful profile of those seemingly prone to horrific violence.
What's more, experts say many if not most of the gun-related tragedies that have captured national attention in recent years appear unlikely to have been prevented, even had stronger rules been in place barring people with mental illnesses from owning weapons.
Adam Lanza, the 20-year-old shooter in Newtown, Conn., had no known history of mental illness, despite unconfirmed reports that he was diagnosed with a form of autism. He used firearms legally purchased by his mother, herself one of his victims.
Nor does mental illness appear to explain other widely publicized mass murders, including the slaying of six people at a Sikh temple in Wisconsin last year, or the shooting rampage that took the lives of eight people in Manchester, Conn., in 2010.
Other mass murderers, including Virginia Tech shooter Seung-Hui Cho and Long Island Rail Road killer Colin Ferguson, may have failed background checks had a federal database been more complete. James Holmes, who allegedly killed 12 people in Aurora, Colo., last year, had been treated for mental illness but didn't meet the legal standards that would have blocked him from buying guns.
Zeroing in on mental health problems in the face of an overwhelming preponderance of shootings involving people without such conditions threatens to mislead the public about the nature of the epidemic at hand, argues Garen Wintemute, the director of the Violence Prevention Research Program at the University of California-Davis School of Medicine.
"We're focused on mass shootings and those perpetrators are thoroughly investigated and we come away thinking that they're mentally ill," when that isn't always the case, said Wintemute, who is also a medical doctor. "The vast majority of firearms violence is not committed by people who are crazy. It is committed by people like us."
This disconnect in public understanding of gun violence stems from the nature of the events that tend to stimulate attention, such as the tragedy in Newtown. The media saturation that follows turns the likes of Adam Lanza and James Holmes into representatives of the much broader issue of gun violence, while prompting revulsion over the scope of the problem.
The problem is indeed vast by any statistical measure. Homicides and suicides using guns made up 57 percent of violent deaths in the United States in 2010, according to data compiled by the Centers for Disease Control and Prevention. That year, guns killed 30,470 people.
But those with mental illness are flawed examples of the causes of American gun violence, and putting a spotlight on their cases oversimplifies the problem while effectively demonizing their ailments, said Stephen Hoge, a professor at the Columbia University Department of Psychiatry and a forensic psychiatrist.
"People want to believe that the problem is easy to solve, and that they can somehow insulate themselves from the risks of gun violence by insulating themselves from people with mental illness," said Hoge.
In reality, gun violence tends to be provoked by commonplace situations faced by people who do not stand out as particularly remarkable in terms of their mental well-being, he added. "In some cases, the perpetrators are motivated by delusions or psychotic beliefs,” Hoge said. “In other cases, they're motivated by jealousy, rage, feelings of having been intimidated, disrespected, abused.”
In short, they rarely fit neatly into a readily identifiable profile that lends itself to prevention.
"There are so many people who need mental health care," said Ronald Honberg, the national director for policy and legal affairs at the National Alliance on Mental Illness. "It's unfortunate that we only talk about the holes in our mental health system and the need for better mental health care in this country when really horrible things happen."
But advocates for expanded mental health services also fear that such attention comes at a profound cost that sets back effective treatment.
"There's an undeniable stigmatizing impact of discussing mental health in the context of gun violence," said Appelbaum, of Columbia University. This furthers the stereotype that people with mental illnesses are more violent than the rest of society, he said.
That public perception is reflected in a survey published in the New England Journal of Medicine this week: 46 percent of respondents said they believe those with serious mental illnesses are more dangerous than others, 71 percent said they wouldn't want to work closely with a person who had a mental illness, and 67 percent said they wouldn't want a neighbor with a mental illness.
Opponents of stricter limits on firearms ownership, like bans on assault weapons and high-capacity magazines, stress that keeping guns out of the wrong hands is the key to reducing violence. NRA CEO Wayne LaPierre has called for a "national registry" of people with mental illnesses, and pro-gun-rights lawmakers emphasize addressing mental health over policies that would reduce firearms ownership.
In testimony before the Senate Judiciary Committee Wednesday, LaPierre expressed support for items on Obama's mental health agenda while rejecting gun-control measures like universal background checks.
"We need to look at the full range of mental health issues, from early detection and treatment, to civil commitment laws, to privacy laws that needlessly prevent mental health records from being included" in the background check system, he said.
The NRA surveyed its members this month and found 86.4 percent of them believe that "strengthening our laws regarding mental health records to keep all firearms out of the hands of the mentally ill" would be the most effective way to prevent mass murders.
To gun-control advocates, these arguments smack of changing the subject.
"It is a political strategy to distract," said Richard Aborn, the president of the Citizens Crime Commission of New York City. "It would be as foolhardy as saying, 'Well, if we just ban assault weapons, we solve the gun violence problem,' as to say, 'If we just solve the mental health issue, we solve the gun violence problem.'"
Mental health professionals say there's no reliable way to predict violence unless patients declare their intentions to hurt themselves or others.
"It is virtually impossible to identify who among the mentally ill are likely to be violent," Columbia University's Hoge said. "To have a policy that is based on identifying individuals who are likely to become violent is a failed policy from the beginning."
Federal law already prohibits gun ownership by some people with mental illnesses. Under statutes dating to 1968, people who have been involuntarily committed to mental institutions or subject to legal sanctions related to mental health conditions aren't permitted to possess firearms.
But the federal database for gun-sales background checks is missing millions of records regarding buyers' mental health histories, largely because states aren't submitting the appropriate information to the Federal Bureau of Investigation, Mayors Against Illegal Guns reported in 2011.
The definition of who should be prohibited from obtaining firearms is flawed, so it limits people who don't pose a threat while at the same time allowing potentially dangerous people to get guns, said Ladd Everitt, the director of communications for the Coalition to Stop Gun Violence.
"The problem with mental health and guns is that we haven't updated that standard since 1968 and the standard is arbitrary, nondescript and totally unfair," Everitt said. "I don't think it's stopping many people at all."
Factors such as previous acts of violence or the combination of mental illness and substance abuse may be more predictive of future violence, and the prohibitions against gun ownership could be broadened to reflect that fact, Everitt said.
As part of Obama's overall strategy, he ordered Attorney General Eric Holder to make recommendations for altering the current restrictions on firearms ownership "to ensure dangerous people aren't slipping through the cracks," the White House's summary of the president's plan says.
Wintemute, the University of California expert, said if policymakers hope to actually reduce gun violence, they must be willing to deprive larger numbers of people of the right to own firearms, despite the limitations of forecasting individual threats.
"Are we, in those instances at least, willing to say this person whose individual risk cannot be told with certainty is a member of a group of people that, as a group, are reliably at higher risk than other people?" he said. "That's as good as the science can get."
Need help? In the U.S., call 1-800-273-8255 for the National Suicide Prevention Lifeline.