Researchers Issue First Report on Mass Shootings from the Columbia Mass Murder Database

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 Gary Brucato, PhD and Ragy R. Girgis, MD have published their first report on mass shootings from the Columbia Mass Murder Database (CMMD), appearing online in Psychological Medicine on February 17, 2021. The investigators sought to gain much-needed insight into the relationship between serious mental illness and mass shootings. Creating the CMMD involved extensive review of 14,785 murders publicly described in English in print or online, occurring worldwide between 1900 and 2019. 

The investigators identified 1,315 mass murders of all types, from all over the world, to better understand mass shooting events. Brucato, Girgis and colleagues found, contrary to popular belief, that serious mental illness was present in only 11% of all mass murderers and in only 8% of mass shooters. 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 report 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 Paul S. Appelbaum, MD, 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."


The Columbia University Department of Psychiatry is among the top ranked psychiatry departments in the nation and has contributed greatly to the understanding and treatment of brain disorders. Co-located at the New York State Psychiatric Institute on the NewYork-Presbyterian Hospital/Columbia University Irving Medical Center campus in Washington Heights, the department enjoys a rich and productive collaborative relationship with physicians in various disciplines at the Columbia University Vagelos College of Physicians and Surgeons. Columbia Psychiatry is home to distinguished clinicians and researchers noted for their clinical and research advances in the diagnosis and treatment of depression, suicide, schizophrenia, bipolar and anxiety disorders, eating disorders, substance use disorders, and childhood psychiatric disorders.

Columbia University Irving Medical Center provides international leadership in basic, preclinical, and clinical research; medical and health sciences education; and patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the Vagelos College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Columbia University Irving Medical Center is home to the largest medical research enterprise in New York City and State and one of the largest faculty medical practices in the Northeast. For more information, visit or


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