"Writing in the Nov. 16, 2006, New England Journal of Medicine, Dr. Richard A. Friedman of the Weill Cornell Medical College notes that only about 3 to 5 percent of violence in the general population is attributable to those with 'serious mental illness,' conventionally defined as schizophrenia, major depression, or bipolar disorder. The combined lifetime prevalence of these conditions in the US general population is estimated at 19 percent - far larger than their contribution to violence. ..."
"A 1980s study from the National Institute of Mental Health found, using community surveys, that individuals with schizophrenia, major depression, or bipolar disorder were two to three times as likely as those without these illnesses to commit acts of violence. However, to put this in perspective, substance abusers had more than twice the rate of violence as those with these serious mental illnesses.
Moreover, the study found that the vast majority of individuals with serious mental illness were not violent: The lifetime prevalence of violence among people with schizophrenia, major depression, or bipolar disorder was 16 percent, versus 7 percent among people without a mental illness. Those with anxiety disorders had no increased risk of violence.
Even more reassuring is the 1998 MacArthur Violence Risk Assessment Study, led by John Monahan and Henry Steadman, now of Policy Research Associates, which advocates for better mental health services. Unlike the NIMH study, which surveyed people randomly in the community, the MacArthur study evaluated psychiatric patients recently discharged from the hospital. And unlike the NIMH study, which relied solely on self-reports of violence, the MacArthur study used a combination of self-reports, collateral informants, and police and hospital records.
The MacArthur study found that the prevalence of violence among discharged psychiatric patients without a substance abuse disorder was similar to that among community-dwellers who didn't abuse substances. Furthermore, violence by these discharged patients rarely involved vicious attacks on strangers or clinicians. Usually, it resembled violence committed by other community-dwellers, such as hitting a family member inside the home. Lethal violence among the discharged patients was very rare.
In the February 2008 issue of Psychiatric Services, Monahan and Steadman conclude: '. . . for people [with mental illness] who do not abuse alcohol and drugs, there is no reason to anticipate that they present greater risk than their neighbors.'
That said, mental disorders do increase susceptibility to substance abuse, and thus indirectly increase risk of violence. Moreover, as Eric Elbogen of University of North Carolina Chapel Hill School of Medicine wrote me in an e-mail, '. . . a subgroup of people with mental illness likely uses alcohol and drugs to 'self-medicate' psychiatric symptoms.' In my experience, this behavior may reflect the inadequate, fragmented care often provided to those with mental illness who also abuse drugs or alcohol so-called "dual diagnosis" patients.
The image of the violent mentally ill person must also be tempered by research from Linda A. Teplin, of Northwestern University. Teplin finds that those with mental illness are much more likely to be victims than perpetrators of a violent crime. Among psychiatric outpatients, about 8 percent reported committing a violent act, whereas about 27 percent reported being the victim of a violent crime."
Read the full editorial.