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What drives mass shooters? Grievance, despair, and anger are more likely triggers than mental illness, experts say.

Law enforcement and other first responders gather outside Robb Elementary School in Uvalde, Texas, following the shooting there last week.Dario Lopez-Mills/Associated Press

In an effort to make sense of the horrors of mass shootings, politicians and the public are quick to blame mental illness as the root cause of the violence. Last week, in the aftermath of the shooting at an Uvalde, Texas, elementary school, which took the lives of 21 people including 19 children, Governor Greg Abbott attributed the attack to mental illness rather than lenient gun laws.

“Anybody who shoots somebody else has a mental health challenge. Period,” Abbott said, although he acknowledged the shooter had no documented criminal or mental health history. “We as a government need to find a way to target that mental health challenge and do something about it.”


Clearly, no one who commits mass murder is mentally well or emotionally stable. But the assumption that mental illness begets or predicts heinous acts of violence is false, according to experts on school shootings and mass violence. Mass shooters’ desire for death and destruction, experts have found, stems from a variety of circumstances and is rooted in entrenched grievance, despair, and anger, regardless of whether they experience symptoms of mental illness.

“No mass shooter is a mentally healthy person, but to blame mental illness as the cause of mass shootings fundamentally just isn’t supported by case evidence and by scientific study,” said Mark Follman, a journalist and author of the new book “Trigger Points: Inside the Mission to Stop Mass Shootings in America.”

A decade ago, Follman (along with this reporter) created the first open-source database documenting US mass shootings. Far from having delusional thoughts or hallucinations, most mass shooters believe they are making reasoned and calculated choices based on real or perceived injustices in their lives, Follman and other experts contend. Their violent thinking is often validated in the dark corners of the Internet, where they are radicalized even further. Some study other perpetrators and try to emulate them.


“They don’t just come out of nowhere,” Follman said. “It’s not just crazy people who are snapping. It’s not an impulsive act. None of that is true.”

Mass shootings in the United States are rare, accounting for less than half a percent of all homicides, and therefore difficult to study or reach firm conclusions about. The motivations of mass shooters are also hard to parse because many die at the scene of their attacks and leave nothing behind to explain their actions. But research has shown the causal link between mental illness and mass violence is tenuous.

“Age, social networks, access to firearms, past history of violence, substance use — those are generally far more predictive of violence than a mental illness diagnosis,” said Jonathan Metzl, director of the Department of Medicine, Health, and Society at Vanderbilt University. “In fact, a mental illness diagnosis is predictive of [being a victim of] violence.”

A 2018 study by the FBI’s Behavioral Analysis Unit evaluating 63 active shooters between 2000 and 2013 found that a quarter were known to have been diagnosed with any kind of mental illness, and just 3 of the 63 had a verified psychotic disorder.

Although 62 percent of shooters showed signs that they were struggling with issues like depression, anxiety, or paranoia, their symptoms, the study notes, may ultimately have been “transient manifestations of behaviors and moods” that would not qualify them for a formal diagnosis.


Formally diagnosed mental illness, the study concludes, “is not a very specific predictor of violence of any type, let alone targeted violence,” given that roughly half of the US population experiences symptoms of mental illness over the course of their lifetimes.

Forensic psychologist Jillian Peterson, cofounder of The Violence Project, a think tank dedicated to reducing violence, said mass shooters are typically younger men, channeling their pain and anger through acts of violence and aggression. For many mass shooters, Peterson said, their path to violence begins with early childhood trauma. They often share a sense of “entitlement,” she said — to wealth, power, romance, and success. When they don’t achieve those goals, they become enraged and search for a scapegoat.

”As they get older, you see a lot of despair, hopelessness, self-hate — many of them attempt suicide — isolation. And then that kind of despair, isolation, that self-hatred turns outward,” Peterson said. “School shooters blame their schools. Some people blame a racial group or women or a religious group or the workplace.”

But mental illness, she said, is rarely an exclusive motive for mass shooters. In a study published last year, Peterson and her colleagues analyzed a dataset of 172 mass shooters for signs of psychosis — features of schizophrenia and other mood disorders. Although mental illness and psychotic disorders were overrepresented among the mass shooters they studied, Peterson’s study found most mass shooters were motivated by other factors, such as interpersonal conflicts, relationship problems, or a desire for fame.


Peterson’s study found psychotic symptoms, such as delusions or hallucinations, played no role in almost 70 percent of cases, and only a minor role in 11 percent of cases, where the shooters had other motives. In just 10 percent of cases, perpetrators were directly responding to their delusions or hallucinations when they were planning and committing their attacks.

“People tend to think the people who do this, they’re just evil and they’re insane. But that really prevents us from being able to engage in the type of prevention work we need to do,” Peterson said. “We need to be able to recognize that people in our lives can go down this pathway.”

Although they are often stereotyped as friendless loners, mass shooters do not all fit a single psychological profile, according to school shooting expert Peter Langman, a psychologist and author of several books, including “Warning Signs: Identifying School Shooters Before They Strike.” But many follow similar patterns, he said.

In the months or year preceding the attack, mass shooters often experience social setbacks and personal failures, according to Langman. Some were bullied, faced disciplinary action at school, endured romantic rejection, or were abused by their parents.

“There’s a lot of different things that can contribute to putting someone on the path of violence,” Langman said. “Often there’s a sense of a grievance.”

Mass shooters, on average, experienced 3.6 distinct “stressors” in the year preceding their attacks, according to the FBI study. Those stressors included financial strain, problems at work, or conflicts with their peers and spouses, in addition to issues with their mental health.


They also exhibited an average of 4.7 “concerning behaviors,” observable by others, the FBI found. More than half, for example, leaked their intent to cause violence prior to carrying out their attacks. More than 40 percent had school- or work-related performance issues, and a third showed signs of anger and physical aggression.

“These perpetrators are in crisis. Their behavior is changing. They’re acting differently. People around them are noticing,” Peterson said. “We don’t have to connect that to a diagnosable mental illness to know that we need intervention there.”

In every shooter’s life, the FBI found, these behaviors caught the attention of at least one person. But in more than half the cases — 54 percent — those who observed the potential warning signs did nothing, while 41 percent reported what they had noticed to law enforcement.

Indeed, there were several warning signs that Uvalde gunman Salvador Ramos intended to cause harm. He threatened teenage girls online and posted photos of semiautomatic rifles on Instagram. He even wrote of his plans to “shoot an elementary school” in a private Facebook message. Minutes later, authorities say, he barricaded himself in a classroom and launched his deadly rampage.

“The message has to be: report threats you hear,” Langman said. “If you see something, say something.”

Deanna Pan can be reached at Follow her @DDpan.