A research team at the Center of Prevention and Evaluation (COPE) at Columbia University Irving Medical Center and the New York State Psychiatric Institute, led by Drs. Gary Brucato and Ragy R. Girgis, found that, contrary to popular belief, serious mental illness was present in only 11% of all mass murderers and in only 8% of mass shooters.
The study—the first published report on mass shootings from the Columbia Mass Murder Database—appeared online Feb. 17th in Psychological Medicine.
The investigators sought to gain much-needed insight into the relationship between serious mental illness and mass shootings. Creating the database involved extensive review of 14,785 murders publicly described in English in print or online, occurring worldwide between 1900 and 2019.
In the study, the investigators analyzed 1,315 mass murders of all types, from all over the world, to better understand mass shooting events.
People who committed mass murder by other means, such as fire, explosives, poison, stabbing, bludgeoning, or driving vehicles into crowds, had a prevalence of serious mental illness of 18%. Although almost two-thirds of all mass murders were committed with firearms, non-firearm means resulted in significantly more casualties per event.
Examining a wide array of demographic, psychological and other background features of mass murderers available in multiple public reports, the researchers also found that U.S.-based mass shooters were more likely to have legal histories, use recreational drugs or misuse alcohol, or have histories of non-psychotic psychiatric or neurologic symptoms.”
They also reported that non-automatic firearms are the weapon of choice of most mass shooters. Furthermore, the investigators found that, among mass shooters in the U.S., the only distinguishing factor between those who used non-automatic vs. semi-automatic weapons is that individuals with any psychiatric or neurologic condition were more likely to use semi-automatic weapons. These findings may have key implications for the way background checks preceding weapon purchases should be conducted.
The authors also found that since 1970 the rate of mass shootings has been far greater than the rate of non-firearm mass murder, with the vast majority of mass shootings occurring in the United States.
Dr. Brucato remarked, “The findings from this potentially definitive study suggest that emphasis on serious mental illness, such as schizophrenia or psychotic mood disorders, as a risk factor for mass shootings is given undue emphasis, leading to public fear and stigmatization.”
Coauthor Dr. Paul S. Appelbaum, known for his work on violence in psychiatric samples, noted, “These data suggest that other difficulties, such as legal problems, substance and alcohol use, and difficulty coping with life events seem more useful foci for prevention and policy than an emphasis on serious mental illness.”