Mental health advocates and former patients say the finding could help chip away at the stereotypes that have provoked unnecessary fear and driven misguided public policy for years.
"For the vast majority . . . this stigma of violence and other persistent and inaccurate myths keep us in the closet," says Ken Steele, a schizophrenic from New York who now fights for the rights of the mentally ill.
Discharged mental patients with substance abuse problems are five times as likely to commit acts of violence as people without drug problems, according to the study, published in the May edition of the Archives of General Psychiatry.
Non-patients with substance abuse problems had three times the violence rate of the general population. But the violence rate was about the same for patients and non-patients who were drug-free.
The study followed 951 acute psychiatric patients in the year after their discharge in 1994 from hospitals in Pittsburgh, Kansas City and Worcester, Mass. Researchers compared the findings with a sample of 519 non-patients who lived in the same neighborhoods as the patients discharged in Pittsburgh.
John Monahan, one of the study's authors, says several recent surveys have shown that most Americans believe mentally ill people are prone to violence.
"I think the public's fears are greatly exaggerated," said Monahan, a psychologist at the University of Virginia School of Law.
He hopes the study's findings will help undo some of those fears, which he believes led to some unfortunate practices in the past
The researchers did find that alcohol and other drugs made study participants dangerous to others, particularly family members, a finding that is prompting Monahan and his colleagues to call for better integration between providers of mental health services and substance abuse treatment.
"Often times, the discharged patients don't get from one to the other," Monahan says. "They fall between the cracks."
Steele, who's been on medication for three years, says that even when he was abusing alcohol he didn't hurt anyone.
Now on medication that has made him "delusion-free and voice-free" for three years, Steele is well enough to help plan public events for the mentally ill.
"How often do you hear the word schizophrenic said in a positive way or in association with something that's being done positively?" he said.
Robert Bernstein, executive director of the Bazelon Center for Mental Health Law in Washington, said the public generally becomes aware of serious mental illness only when "something has gone wrong."
"But for the most part, mentally ill people live successfully, and they're good neighbors, and you don't hear about violence," he said. "You don't hear abut it because you don't necessarily know they have mental illness."
By Martha Irvine