Crime Scene – Police Line Tape

(© aijohn784 -

STANFORD, Calif. — There is no understanding the motive behind an act as heinous as a mass shooting, but a new study may have uncovered a medical explanation. The first ever analysis of available medical evidence pertaining to U.S. mass shooters finds most perpetrators had a psychiatric disorder for which they hadn’t received any medication or treatment.

“Without losing sight of the larger perspective that most who are violent are not mentally ill, and most of the mentally ill are not violent, our message is that mental health providers, lawyers, and the public should be made aware that some unmedicated patients do pose an increased risk of violence,” says Ira D. Glick, MD, of Stanford University School of Medicine and colleagues, via a media release.

Study authors focused on 115 individuals who had committed a mass shooting in the United States between 1982 and 2019. Notably, the database used to identify the perpetrators excluded shooting incidents related to “conventionally motivated” crimes such as an armed robbery or act of gang violence.

“In the vast majority of the incidents identified in the database, the perpetrator died either during or shortly after the crime,” researchers note.

Analyzing the mind of a mass shooter

So, researchers decided to focus solely on the 35 cases in which the shooter survived and went to trial. These were the only cases that provided enough information on the individuals’ mental state. From there, the team spent countless hours analyzing files from the shooters’ psych evaluations and speaking with the doctors and psychologists who had interviewed the perpetrators. They also examined public records, court proceedings, video recordings of interviews, and social media posts or other writings by each shooter.

“Based on this data, 32 of the 35 perpetrators had signs and symptoms of brain illness, which fit scientific diagnostic criteria for a clinical psychiatric disorder,” Dr. Glick comments.

Study authors report 18 of the examined shooters had schizophrenia. Another 10 had a variety of conditions including delusional disorder, bipolar disorder, personality disorders, and substance-related disorders. For three shooters, researchers did not have enough information to make an informed diagnosis and four perpetrators did not appear to have any psychiatric disorder.

Astoundingly, not a single one of the 28 surviving shooters with an apparent psychiatric issue received treatment or had taken any medication prior to their crimes.

Can better psychiatric care save lives?

Researchers then examined another 20 mass shooters who died at the scene of their crimes using any available data. Researchers say eight of those shooters had schizophrenia, seven had other disorders, and five had unknown conditions. Once again, not a single one was being treated for any psychiatric condition.

The frequency of U.S. mass shootings in recent years is deeply unsettling. Yet, this is one of the first research projects to focus on the brain health of the shooters. With these findings in mind, ensuring psychiatric help and support for the people who need it is imperative.

“The psychiatric disorders seen in perpetrators of mass shootings are serious brain illnesses – as much in need of proper diagnosis and treatment as heart disease or any other medical condition,” Dr. Glick concludes. “We need to reduce the stigma associated with these diseases to enable patients to receive appropriate and adequate psychiatric medication and other treatments. By actually talking to patients and their significant others, we have the opportunity to save lives.”

The study appears in the Journal of Clinical Psychopharmacology.

About John Anderer

Born blue in the face, John has been writing professionally for over a decade and covering the latest scientific research for StudyFinds since 2019. His work has been featured by Business Insider, Eat This Not That!, MSN, Ladders, and Yahoo!

Studies and abstracts can be confusing and awkwardly worded. He prides himself on making such content easy to read, understand, and apply to one’s everyday life.

Our Editorial Process

StudyFinds publishes digestible, agenda-free, transparent research summaries that are intended to inform the reader as well as stir civil, educated debate. We do not agree nor disagree with any of the studies we post, rather, we encourage our readers to debate the veracity of the findings themselves. All articles published on StudyFinds are vetted by our editors prior to publication and include links back to the source or corresponding journal article, if possible.

Our Editorial Team

Steve Fink


Chris Melore


Sophia Naughton

Associate Editor