Is There a Schizophrenia-Violence Link?

August 17, 2009

British researchers in the Department of Psychiatry at the University of Oxford have demonstrated an association between schizophrenia and violence, and more importantly, that the association is greatly increased with drug and alcohol abuse.

British researchers in the Department of Psychiatry at the University of Oxford have demonstrated an association between schizophrenia and violence, and more importantly, that the association is greatly increased with drug and alcohol abuse. However, their study results also show that the risk of violence among those with psychoses and a “substance use disorder is no greater than those who have a substance use disorder but who do not have a psychotic illness,” leading to the conclusion that schizophrenia and other psychotic illnesses don’t seem to be a cause for any further risk of violence beyond that associated with substance abuse. This latter finding suggests that the focus for reducing violence among the public be aimed at drug and alcohol abuse as opposed to mental illness. “As substance use disorders are three to four times more common than the psychoses, public health strategies to reduce violence could focus on the prevention and treatment of substance abuse at an individual, community and societal level,” wrote the authors.

Led by Seena Fazel, the researchers reviewed all previous studies that looking at psychotic illness and violence risk, attempting to resolve the various, and sometimes conflicting, conclusions. Their efforts could help put rest an “opinion emerging in the last couple of decades that there is a modest association between schizophrenia and violence [that] is thought to have influenced policy and legal developments, with the number of patients in secure hospitals increasing in Western countries.”

Fazel’s team identified 20 studies that compared to the general population to people with a psychotic illness in regards to violence risk, using statistical tools to account for differences between them. They did find that “men with schizophrenia or other psychoses were typically four to five times as likely to commit a violent act as a man in the general population; for women with schizophrenia or other psychoses there was an eight times greater risk of violence than women in the general population,” the latter finding perhaps due to a lower prevalence of drug and alcohol use among the general female population.

However, after analyzing the differing characteristics between the 20 studies, the team found that the only factor that caused variation between the studies was substance abuse. And although risk of violence was greatly increased with substance use among those with psychotic illnesses, the increased risk was similar to that seen in the general population with substance abuse.