Only 7.5 percent of crimes committed by people with serious mental disorders were directly linked to their symptoms, says a new study by the American Psychological Association.
The study was published in the “APA journal Law and Human Behavior” as How Often and How Consistently do Symptoms Directly Precede Criminal Behavior Among Offenders With Mental Illness?
“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.”
Researchers studied 429 crimes that were committed by 143 mentally ill offenders who were former defendants in a Minneapolis mental health court.
Nearly two-thirds of the study participants were men around the age of 40. Researchers reviewed the offenders’ criminal histories and social worker files to determine their association with three major mental health disorders: schizophrenia disorders (delusions and hallucinations), major depression (hopelessness and suicidal thoughts), and bipolar disorder (risk-taking behavior and impulsivity). The crimes were rated as:
No relationship between symptoms of mental illness and the crime
A crime could be rated as mostly related or unrelated if the symptoms contributed to crime but were not soley responsible for the act. The participants were also interviewed for two hours about their mental health symptoms and criminal history over average period of 15 years.
Researchers did not find predictable patterns that linked the symptoms of mental illness and criminal conduct
In a small number of cases, crimes were directly related to the symptoms of the offenders’ mental disorders: schizophrenia disorders (4 percent); major depression (3 percent); and bipolar disorder (10 percent)
Two-thirds of mentally ill offenders who committed crimes related to symptoms also committed crimes for other reasons such as homelessness, unemployment, poverty and substance abuse
“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.
The U.S. Bureau of Justice Statistics states that there are more than 1.2 million prisoners with mental illness in U.S. prisons or jails. Mentally ill people are also on probation or parole at a rate that is two to four times the rate of the general population.