Past research indicates that mental illness is noted to be a modest risk factor for violence, with only 4% of violence in the United States attributed to individuals with mental illness”(Monahan et al., 2001 and Swanson, 1994, as cited in Skeem, Kennealy, Monahan, Peterson, & Appelbaum, 2015). Rather, violent acts committed by individuals with mental illness is only associated with a fraction or a small subgroup of this population.
Unfortunately, little is known about how often and how consistently high-risk individuals with mental illness experience delusions or hallucinations prior to violent acts (Skeem et al., 2015). Thus, in order to determine if psychosis preceded violence, Skeem, Kennealy, Monahan, Peterson, and Appelbaum (2015) used data from the MacArthur Violence Risk Assessment study to examined 305 violent incidents committed by 100 former inpatients.
Results indicated that in 12% of the 305 incidents, delusions and hallucinations immediately preceded the act. Also the data indicated that for a large portion of the sample, violence was consistently not preceded by psychosis (80%) whereas a smaller group of individuals reported some psychosis-preceded violence (20%). Again, this suggests that within the sample, groups can be disaggregated into the majority with non-psychosis preceding violence from those with psychosis-preceding violence.
This study does not indicate a causal link between psychosis and violence; rather, it indicates a relationship or temporal ordering for these events. Overall, the data indicate that psychosis sometimes preceded violence for high-risk individuals. Yet, psychosis-preceded violent acts tend to be concentrated within a subgroup of high-risk patients. Treatment implications note that for individuals with psychosis-preceded violence, delusions and hallucinations should be a focus of treatment targeting violence prevention. Even still, providers must consider other precipitating factors associated with violence.
References
Skeem, J., Kennealy, P., Monahan, J., Peterson, J., & Appelbaum, P. (2015). Psychosis uncommonly and inconsistently precedes violence among high-risk individuals. Clinical Psychological Science. Advance Online Publication. doi: 10.1177/2167702615575879
Dannie S. Harris, M.A., M.A., M.A.Ed., Ed.S.
WKPIC Practicum Trainee