As US health secretary, Robert F. Kennedy Jr. has drawn a lot of attention for promoting pseudoscience and disproven theories, especially on vaccines. He is using that playbook on another major public health issue: gun violence, which remains the leading cause of death for kids in America. When it comes to school shootings and other mass shootings, here’s what RFK Jr. wants you to believe: It’s not the guns, he argues, it’s the pills.

The fringe theory that antidepressants can cause people to turn violent has been around for decades, focused primarily on selective serotonin reuptake inhibitors, or SSRIs, which are the most common class of these drugs. But extensive research by mental health and violence prevention experts has found no credible evidence that antidepressants cause or contribute to mass shootings.

The generalized claim that SSRIs can make people violent—and that they supposedly gave rise to the shootings epidemic—traces in part to an unscientific anti-Prozac campaign in the 1990s from the Church of Scientology and gained some traction in online forums after the Columbine High School massacre in 1999. Disgraced conspiracy theorist Alex Jones, who helped create a miasma of lies claiming that the 2012 mass shooting at Sandy Hook Elementary School was faked, has also peddled the theory.

Proponents of the SSRI theory use anecdotal, often unconfirmed details about shooters’ health histories to argue causation. But multiple studies from experts in psychiatry, law enforcement, and public health show that the theory has no merit. Data on shooters spanning more than a decade from the FBI’s Behavioral Analysis Unit has been used specifically to examine the claim that psychiatric drugs are at the root of school shootings; independent researchers concluded from the FBI data that “most school shooters were not previously treated with psychotropic medications—and even when they were, no direct or causal association was found.”