In a study of crimes committed by people with serious mental disorders, only 7.5 percent were directly related to symptoms of mental illness, according to new research published by the American Psychological Association.
Researchers analyzed 429 crimes committed by 143 offenders with three major types of mental illness and found that 3 percent of their crimes were directly related to symptoms of major depression, 4 percent to symptoms of schizophrenia disorders and 10 percent to symptoms of bipolar disorder.
“When we hear about crimes committed by people with mental illness, they tend to be big headline-making crimes so they get stuck in people’s heads,” said lead researcher Jillian Peterson, PhD. “The vast majority of people with mental illness are not violent, not criminal and not dangerous.”
The study was conducted with former defendants of a mental health court in Minneapolis. The participants completed a two-hour interview about their criminal history and mental health symptoms, covering an average of 15 years. The study, published online in the APA journal Law and Human Behavior, may be the first to analyze the connection between crime and mental illness symptoms for offenders over an extended period of their lives, said Peterson, a psychology professor at Normandale Community College in Bloomington, Minn.
The study didn’t find any predictable patterns linking criminal conduct and mental illness symptoms over time. Two-thirds of the offenders who had committed crimes directly related to their mental illness symptoms also had committed unrelated crimes for other reasons, such as poverty, unemployment, homelessness and substance abuse, according to the research. “Is there a small group of people with mental illness committing crimes again and again because of their symptoms? We didn’t find that in this study,” Peterson said.
In the United States, more than 1.2 million people with mental illness are incarcerated in jails or prisons, according to the federal Bureau of Justice Statistics. People with mental illnesses also are on probation or parole at two to four times the rate for the general population.