Patients' Violence Risk Tied to Specific Factors

The relationship between mental illness and violence is complex and unsettled, and it is likely to remain so, even after publication of a new study drawing on nationwide survey data.

Tragedies like recent mass shootings on university campuses, especially when perpetrated by people described as formerly in psychiatric treatment, connect violent acts with mental illness in the public's mind.

Yet Sally Johnson, M.D., a professor of psychiatry at the University of North Carolina (UNC) at Chapel Hill, told Psychiatric News,“ the issue of dangerousness is more complicated than meets the eye.”

A decade ago the MacArthur Violence Risk Assessment study reported that patients discharged from psychiatric facilities were no more likely to commit violent acts than anyone else. Other scholars disagreed, and the published record is divided. Some research concluded that there is a causal connection between some mental illnesses and violent behavior while other studies say that the link appears only when mental illness is accompanied by drug or alcohol abuse, or other risk factors.

Now, Johnson and her colleague Eric Elbogen, Ph.D., an assistant professor of psychiatry at UNC, have contributed a new study to the debate. Drawing on data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), the two researchers, both affiliated with UNC's Forensic Psychiatry Program and Clinic, found that severe mental illness alone did not predict violent behavior.

“[P]eople with mental illness did report [engaging in] violence more often, largely because they showed other factors associated with violence,” wrote Elbogen and Johnson in the February Archives of General Psychiatry.

They used NESARC data collected by the National Institute on Alcohol Abuse and Alcoholism in two waves from people living in the United States in 2001-2003 and 2004-2005. There were 43,093 respondents in the first wave, and 34,653 who completed the second wave. The sample was weighted to reflect the general population. Respondents were asked if they had lifetime or recent (in the prior 12 months) diagnoses of a major mental disorder or substance dependence, as well as if they had engaged in violence.

The NESARC data allowed researchers to look at respondents at two time points and see if their earlier psychiatric status predicted later violence.

About 10.9 percent of respondents said they had been diagnosed with schizophrenia, bipolar disorder, major depression, or substance abuse disorder alone, while 9.4 percent had co-occurring mental and substance abuse disorders. The researchers also included other factors in their analysis. These included dispositional factors (age, race, gender, education, income), historical factors (parental criminal history), and contextual factors (victimized in past year, divorced or separated, unemployed), as well as clinical factors.

The incidence of violent behavior was significantly higher among persons with severe mental illness only when other factors—particularly substance abuse or dependence—were present, reported Elbogen and Johnson.

“[T]he current results show that if a person has severe mental illness without substance abuse and a history of violence, he or she has the same chances of being violent during the next three years as any other person in the general population,” they wrote. “Multivariate analyses confirmed that severe mental illness alone did not significantly predict committing violent acts; rather, historical, dispositional, and contextual factors were associated with future violence.”

Overall, this study is fairly consistent with previous reports, said Renée Binder, M.D., a professor of psychiatry at the University of California at San Francisco, who has also studied dangerousness.

“The study is strengthened because it is based upon data from more than 34,000 individuals, but it has severe limitations,” she said. Those include the self-report format of the survey, the absence of personality disorder or traumatic brain injury in the original survey, and lack of information on the stage of mental illness during which violent behavior occurred.

“A person diagnosed with schizophrenia may have a greater risk for violence when delusional, but much less when stabilized on medication,” said Binder in an interview.

Elbogen agreed, noting that the NESARC survey was primarily designed to gather data about alcohol use and consequences, but its size and the scope of its questions could still be useful.

For one, it allowed Elbogen and Johnson to go beyond previous cross-sectional research and make use of a survey that was both longitudinal and representative.

Binder also said the inclusion of “perceived threats of violence” by a mentally ill person as a factor was valuable, since it went beyond simple paranoia to include elements of the respondent's life that posed genuine threats to safety.

“We started with no preconceptions in the context of the dangerousness debate,” said Elbogen. “We're trying to talk to both camps, and we hope it helps clarify the discussion.”

Johnson noted that there were potential policy implications to their research, especially in an age when public mental health budgets are dwindling.

“We have to look more closely at how we assume that treating people for mental illness is the only or even the best intervention needed to help them and to lessen the risk of danger,” she said. “More broadly based social interventions like job training and placement, family therapy, housing, and so on might also lessen the risk of violence.”

“The Intricate Link Between Violence and Mental Disorder” is posted at<http://archpsyc.ama-assn.org/cgi/content/full/66/2/152>.▪