While some mass shootings are committed by people with diagnosed mental illnesses, a life crisis is a better predictor of violence, researchers say.

Selected excerpts:

…mental illness is not a useful means to predict violence. About half of all Americans will experience mental health issues at some point in their lives, and the vast majority of people with mental illness do not kill.

“Do you or do you not have a mental health diagnosis?” said Jillian Peterson, a co-founder of the Violence Project, a research center that has compiled a database of mass shootings from 1966 on and studied perpetrators in depth. “In many cases, it doesn’t really matter. It’s not the main driver.”

Instead, many experts have come to focus on warning signs that occur whether or not actual mental illness is present, including marked changes in behavior, demeanor or appearance, uncharacteristic fights or arguments, and telling others of plans for violence, a phenomenon known as “leakage.”

This focus is far from perfect — it can be exceedingly difficult to weed out serious threats from many more that are idle, impetuous or exaggerated. But the warning signs approach has benefits: It can work even when the mental health system does not, and it sidesteps the complaint that blaming mass shootings on mental illness increases negative attitudes and stigma toward those who suffer from it.

“When someone treats you like a person when you don’t even feel like a human, it’ll change your entire world.”

Aaron Stark. From “I was almost a school shooter,” TEDxBoulder, June 26, 2018.

Crisis can be triggered or exacerbated by mental illness, but also by loss of a job, a breakup, divorce, death or other events. The mother of the Parkland [Florida] gunman died three months before he carried out his attack at the high school, from which he had been expelled.

This suggests that potential violence can be averted. In a TEDx talk called “I Was Almost a School Shooter,” a man named Aaron Stark recounted how a friend’s simple invitation to watch a movie helped divert him from his plans. “When someone treats you like a person when you don’t even feel like a human, it’ll change your entire world,” he said.

In interviews with perpetrators, Dr. Peterson said, “We would always ask, is there anything that could have stopped you? And they would always tell us, yes.” She added, “I think one of them said probably anyone could have stopped me, but there was just no one.”

— from Dewan, S. (2022, August 22). What are the real warning signs of a mass shooting? The New York Times.