Understanding causal paths between mental illness and violence

The stigma associated with mental illness is a major concern for patients, families, and providers of health services. One reason for the stigmatization of the mentally ill is the public perception that they are violent and dangerous. Although, traditionally, mental health advocates have argued against this public belief, a recent body of research evidence suggests that patients who suffer from serious mental conditions are more prone to violent behaviour than persons who are not mentally ill. It is a point of contention, however, whether the relationship between mental illness and violence is only one of association, or one of causality; that mental illness causes violence. A proven causal association between mental illness and violence will have major consequences for the mentally ill and major implications for caregivers, communities, and legislators. This paper outlines the key methodological barriers precluding casual inferences at this time. The authors suggest that a casual inference about mental illness and violence may yet be hasty. Because a premature statement advocating a causal relationship between mental illness and violence could increase stigma and have devastating effects on the mentally ill the authors urge researchers to consider the damage that may be produced as a result of poorly substantiated causal inferences.