Sunita Sohrabji
American Community Media
Only 5% of mass shootings in the United States are caused by serious mental illness, a finding that sharply contradicts a narrative often repeated after high-profile attacks.
“95% of mass shootings are not related to mental illness,” said Dr. Ragy Girgis, Associate Professor of Clinical Psychiatry at the Columbia University Department of Psychiatry and New York State Psychiatric Institute.
Girgis based his analysis on data collected from the Columbia Mass Murder Database, the largest database of mass murder in existence. The CMMD examined 2300 cases worldwide, dating back to 1900. The database, built by Girgis and his colleagues, included every type of mass murder—defined as three or more fatalities by mass shootings, and attacks carried out with knives, vehicles or other means.
At a Dec. 19 American Community Media news briefing, Girgis was joined by speakers Dr. Daniel Webster, Bloomberg Professor of American Health at Johns Hopkins University; and Sarah Lerner, a teacher at Marjory Stoneman Douglas High School in Parkland, Florida. Webster discussed the dramatic drop in overall gun violence and community-based solutions addressing the crisis.
Portrait of a Mass Shooter
“For a mass murder to be caused by mental illness, it can only really be caused by a psychotic illness,” Girgis said. “Someone who is delusional or hallucinating—believing their life is in danger or hearing voices telling them to kill. That’s very rare, but it does happen.”
About 45–50% of mass shooters have some form of mental illness, but that mirrors the 40–45% lifetime prevalence of mental illness in the general population.
“That five percent difference is not causation,” Girgis said. “People misunderstand correlation.”
The data instead points to a consistent psychological and situational profile of a mass shooter, one shaped by suicide, grievance, gun fascination, and cultural reinforcement of violence.
Suicide
One of the most significant factors is suicide. More than 50% of mass shooters now die by suicide during the attack, a proportion that has steadily increased over time.
“The number one reason people choose firearms is because firearms are the method that they use to take their own life,” Girgis said.
Once someone decides to die, he explained, a key barrier to violence disappears.
“There are three barriers to perpetrating a mass shooting,” Girgis said. “Your moral system, the values you internalize from family and society, and the fear of being caught and incarcerated. Once you decide to take your life, that third barrier has been removed.”
Mass shooters also tend to show an intense fascination with firearms, Girgis said, a factor that has increased immensely as violent movies, video games, television, and music are romanticized in popular culture. While mass murder rates were relatively stable from 1900 through the 1970s, he said, per-capita rates have increased fourfold since then.
Nihilism and Narcissism
A combination of nihilism — a profound sense of emptiness and meaninglessness — and a form of narcissism rooted not in arrogance, but in grievance, are also characteristics found in mass shooters. Nikolas Cruz, currently serving 34 consecutive life sentences for killing 17 people and injuring 17 others on Feb. 14, 2018 at Marjory Stoneman Douglas High School told a psychologist that he chose Valentine’s Day because he felt no one loved him and he wanted to ruin the holiday for everyone.
“This is not narcissism as people commonly understand it,” said Girgis. “It’s very low self-esteem that gets externalized and taken out on other people.”
Gun Violence Rates Are Dropping
While mass shootings capture national attention, they represent only a fraction of gun violence in the United States. Gun homicides in the U.S. have fallen about 40% from their peak in 2021 and 2022, based on 12-month rolling averages compiled by the Real-Time Crime Index, noted Webster.
“The data tell a different story than the headlines,” Webster said. “Nearly all places in the United States have enjoyed much lower rates of homicides in recent years.”
Some cities have seen even sharper declines. Detroit’s homicides are down 76%, while Baltimore, Philadelphia, and New Orleans are down about 60% from their recent peaks.
If current trends hold, Webster said, the U.S. could record its lowest murder rate since national data collection began in 1960.
Interventions
But the country nonetheless continues to remain a global outlier: its homicide rate is eight times higher than other high-income countries, and its firearm homicide rate is 25 times higher. Nearly 80% of U.S. homicides involve guns.
Still, Webster said the recent decline reflects effective policy and investment choices.
After a historic surge during the COVID-19 pandemic — the largest one-year increase in firearm homicides ever recorded — violence began to fall as social systems stabilized. 22,134 murders recorded by the FBI in 2020, the first full year of the pandemic, representing a roughly 34% increase from 2019. 22,830 murders were recorded the following year.
But since then, rates have dropped: in 2024, 16,935 murders were recorded by the FBI.
“Police, courts, schools, health care—all of these systems were strained during the pandemic,” Webster said. “As they strengthened, violence declined.”
Community Action
The 2022 Bipartisan Safer Communities Act — sponsored by Sen. Marco Rubio, R-Florida and signed into law by former President Joe Biden — expanded background checks and injected billions of dollars into community violence intervention programs, mental health services, and local prevention efforts.
Cities expanded group violence reduction strategies, which combine focused law enforcement with social services and support for individuals at highest risk.
Webster also highlighted the impact of regulating ghost gun kits: untraceable firearms that surged during the pandemic. “These guns were going directly to underage youth and people with violent criminal histories,” he said of his research in Baltimore. “After 2022, ghost guns dropped off a cliff.”
Both Webster and Girgis emphasized that firearm policy is central to reducing both mass shootings and everyday gun violence.
“Weaker state firearm laws are very strongly associated with both the number of mass shootings per capita and the number of victims per capita,” Girgis said, noting that most weapons used in mass shootings are legally acquired.
Webster echoed that conclusion. “Stronger gun laws do not eliminate mass shootings entirely,” he said. “But they do lead to fewer of them.”
