The overwhelming majority of people with mental illness never commit violence — they're more likely to be victims of it than perpetrators. But in America today, a tiny number of people may be drawn to express mental distress through mass murder, in ways they never would have been before. The availability and visibility of guns may have changed the way some people respond to internal strife. A number of experts believe that mental illness changes with time, and that our cultures affect the way we express psychological pain.
Medical historian Edward Shorter pioneered the idea of a "symptom repertoire" to explain how the ways people express mental illness have changed over time. Essentially, he says, every society has a certain group of possible symptoms with which mentally ill people express their inner distress. Cultural factors can help determine what these symptoms are.
In the 19th century, when American society was highly religious, Shorter says people with psychosis might smear crosses with excrement or commit other blasphemous acts. But over time, the symptom repertoire for psychosis began to change: "Psychotic people started pulling out a symptom that says, kill other people."
Shorter traces some of this change to the popularization of TV in the late 1940s and 1950s, which let millions of people watch cowboy shows with characters shooting one another, right in their homes. This was "the beginning of a wave that made killing a part of mass culture" — and the advent of violent video games, he says, has accelerated this process. The numbers are still small, but people with psychosis may now express their inner turmoil with gun violence, in ways they wouldn't have a century ago. In America today, mass murder may have become part of the symptom repertoire.
Laurence Kirmayer, a professor of social and transcultural psychiatry, notes that mental illness is by no means the only explanation for gun violence. But, he says, "there are certainly cultural differences in the ways that various forms of distress are expressed." American culture may predispose people toward gun use: "The prevalent discourse in the U.S. around guns as a positive social force or tool ('to prevent government tyranny') makes the use of guns to settle personal grievances or work out imagined slights and humiliations much more thinkable for many people." And pop-cultural depictions of "heroic figures who use guns and other acts of violence to exact revenge" may influence gun crime as well.
Richard McNally, a psychologist who studies mental illness at Harvard, says it's hard to say for sure whether people are expressing mental illness with violence more often now than in the past. But he agrees with Shorter that the form such illness takes can change with time. He notes that post-traumatic stress disorder looks much different than it once did: "shell-shocked" soldiers after World War I exhibited neurological symptoms that today's veterans rarely do, but reported very few of the flashbacks that have since become common.
He also says that, perhaps more clearly than any cultural factor, the sheer availability of guns can influence how mentally distressed people behave. He cites research on Israeli soldiers — when they were allowed to take weapons off-base with them on weekends and holidays, suicide was a problem. But when the soldiers were barred from taking their weapons home with them, suicides on weekends and holidays declined, and didn't go up on other days. People who are considering suicide are actually often ambivalent, says McNally, and "anything that can delay them can often result in the crisis waning."
The evidence is less clear for homicide, but McNally notes that Sandy Hook gunman Adam Lanza also committed suicide. Columbine killers Eric Harris and Dylan Klebold killed themselves as well. Says McNally, "the moral of the story is if we're concerned about people expressing emotional distress in especially dangerous ways, we might think of the ways that might make it difficult for them to do that."
One way to this might be to make semiautomatic weapons more difficult to obtain. Kirmayer offers a similar prescription: "Restrict access to guns and improve access to mental health services." And, he says, we need to lift the stigma against mental illness so that people can seek help rather than harming others or themselves.