Criminal Conduct and Mental Illness: Are there Predictable Patterns?

First Posted: Apr 21, 2014 12:01 PM EDT

Crimes committed by mentally ill individuals may receive frequent headlines. However, a recent study shows that many with serious mental disorders are unlikely to commit illegal acts.

For the study, researchers analyzed 429 crimes committed by 143 offenders with three major types of mental illnesses, including symptoms of major depression, schizophrenia and bipolar disorder.

Findings showed that only 7.5 percent of crimes committed by people with serious mental disorders were directly related to symptoms of 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, via a press release. "The vast majority of people with mental illness are not violent, not criminal and not dangerous."

Former defendants of a mental health court in Minneapolis conducted the study, based on a two-hour interview regarding criminal history and mental health symptoms on an average of 15 years.

The study showed that two-thirds of the offenders who committed crimes directly related to symptoms of their mental illness typically committed unrelated offenses related to other issues, including unemployment, homelessness, poverty and/or 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, via the release.

Almost two-thirds of the study participants were male, with an average age of 40 and evenly divided into white and black offenders. Eighty-five percent of the participants also had substance abuse disorders, and offenders with serious violent crimes were not included in the study.

When researchers examined criminal history and social work files of the participants, findings showed the following, courtesy of the release: "When the directly related and mostly related categories were combined, the percentage of crimes attributed to mental illness symptoms increased from 7.5 percent to 18 percent, or less than one in five of the crimes analyzed in the study. Of crimes committed by participants with bipolar disorder, 62 percent were directly or mostly related to symptoms, compared with 23 percent for schizophrenia and 15 percent for depression. Some participants may have described their mood as "manic" during a crime even though they could have just been angry or abusing drugs or alcohol, so the percentage of crimes attributed to bipolar disorder may be inflated."

As this study further examines the link between mental illness and criminal thinking, other findings have shown more of a direct connection between behavioral disorders and illegal activity.

James Boyd, a homeless man with a history of mental illness, was shot and killed by police in the Sandia Foothills near Albuquerque, after he threatened surrounding officers with a knife. The fatal attack that occurred in March has prompted protests and even an inquiry by the Federal Bureau of Investigation into the death. It has also drudged up concern regarding inadequate mental health services in the country, and the dual roll some are having to take on in the criminal justice system: One as police officer, and the other, as social worker.

"It's like if we stopped treating heart disease until people had heart attacks," said Ronald S. Honberg, director of policy and legal affairs at the National Alliance on Mental Illness, via The New York Times. "We'd be seeing lots of people having heart attacks in the street. That's what's happened in our mental health system. Once people get to the point of crisis, that's a difficult time to start treatment."

Statistics show that in the United States alone, more than 1.2 million people with mental illnesses are in jail or prison, according to the Federal Bureau of Justice Statistics. Those on probation or parole are also two to four times the rate of the general population.

More information regarding the findings can be seen via the APA journal Law and Human Behavior

See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone

©2017 All rights reserved. Do not reproduce without permission. The window to the world of science news.

Join the Conversation

Real Time Analytics