Black men, particularly civil rights activists, have historically received an incorrect diagnosis of schizophrenia at five times the rate of any other group of people, according to a new book by Jonathan Metzl, MD, PhD, an associate professor of psychiatry and women’s studies at the University of Michigan in Ann Arbor.

Race-based misdiagnosis of mental illness was a significant problem during the civil rights struggles of the 1960s and ’70s, when medical professionals labeled activists of color as mentally ill, Metzel argues in The Protest Psychosis: How Schizophrenia Became a Black Disease, published by Beacon Press earlier this month.

For his book, Metzl examined archived medical records from the now-defunct Ionia State Hospital for the Criminally Insane. He found that black men frequently had their diagnosis changed to schizophrenia even when their clinical symptoms hadn’t changed.

According to Metzl, “In the 1920s–1940s, doctors considered the illness as affecting non-violent white individuals (mainly women) but later changed the language to violent, hostile, angry and aggressive as a way to label black men.”

“It’s an easy thing to say this was racism, but it’s a much more complicated story—that’s still playing out in present day,” Metzl added.

Metzl said that despite an increase in cultural competency training for health care professionals, over-diagnosis of schizophrenia in black men remains a problem. “Multicultural training is important,” he concluded, “but it often does little to address how assumptions about race are structurally embedded into health care delivery systems.”