After a lone gunman opened fire on US congresswoman Gabrielle Giffords and her constituents, one can't be blamed for asking if it could happen in Canada. In fact it has happened. More than once. Consider the Dawson College shooting (2006), the Concordia University murders (1992), the École Polytechnic massacre (1989), not to mention two fatal Ontario high school shootings in the mid-seventies. The latter events prompted Canadian gun control laws but failed to prevent further tragedies.
These shootings happened in schools, and these schools are also workplaces, each with more than a thousand employees, all of whom must have wondered, why here, why now? Now, two studies have shed light on the risk factors for extreme violence.
The evidence shatters our assumptions.
Without the kindling effect of alcohol or drugs, mental illness does not predict future violence. "People with schizophrenia who are violent are people who have substance abuse problems, " says Warren Steiner, the psychiatrist-in-chief at the McGill University Health Centre and one of the principal investigators of a follow-up study on the Dawson shooting. "Stimulants like crystal meth are the worst-people get very violent-but alcohol is a big problem too. The two major risks [for violence] are really substance abuse and a previous history of violence," not mental illness per se, Dr Steiner said. "Substance abuse comes with a potential for violent behaviour," and that's what employers should think about-not marginalizing those with mental illness.
His comments are echoed by two major studies, both published in 2009, on the causes of violence. In one study, 35,000 people were interviewed in depth and then followed for five years. The results showed that people with a history of mental illness were no more prone to violence than the average person, unless they also had a problem with alcohol or drugs, according to the study's authors, forensic psychologist Eric Elbogen and forensic psychiatrist Sally Johnson, both at the University of North Carolina School of Medicine.
What are the other risk factors? Being young and male stood out as two of the top risks. Then came a history of violence, a stint in juvenile detention, early physical abuse, parents with a criminal record, and a recent change in marital or employment status. Only then comes mental illness combined with substance abuse. "Recent divorce or recent unemployment were much more highly related to violence than mental illness," said Dr. Elbogen.
Oxford psychiatry professor Seena Fazel and his colleagues came to a similar conclusion. They analyzed 40 years of studies on interpersonal violence and found that severe mental illness on its own doesn't predict it. Substance abuse does.
The confusion may stem from the fact that people with mental illness who don't get timely professional help often self-medicate with alcohol or street drugs. This volatile mix was apparently true of Jared Loughner, the accused gunman in Tucson. Although the young man had not been medically evaluated, he was "probably developing schizophrenia," Dr. Steiner says. "Here was a kid who started to show signs of delusional behaviour at least a year before the incident," who had a drug habit that prevented him from enlisting in the army, and who was given to wild outbursts in classes at a local college. "The school did the right thing by saying he needs an evaluation," Dr. Steiner says. "But there's also a moral obligation to offer services" and not to expect a troubled person to find help on his own.