The influence of treatment attendance on subsequent aggression among severely mentally ill substance abusers.

The interrelationships between severe mental illness, substance use, and aggression are of longstanding importance with implications for community treatment programs, treatment research and public policy. Through the analysis of longitudinal data collected from 278 patients over a 6-month period following admission to an outpatient dual diagnosis treatment program, this study examined the association between dual diagnosis treatment attendance and subsequent aggression among individuals diagnosed with both a severe mental illness and a substance use disorder. We also tested substance use and psychiatric symptoms as mediators of this treatment-aggression relationship. The results of structural equation modeling analyses indicated that dual diagnosis treatment was associated with lower levels of subsequent aggression. Mediational analyses indicated that greater treatment involvement was associated with reduced substance use, which was associated with lower levels of aggression; thus, substance use was found to mediate the relationship between dual diagnosis treatment and aggression. Surprisingly, severity of psychiatric symptoms did not predict later aggression. These findings suggest that targeting substance use reduction in treatment may have the additional benefit of reducing the risk of later aggression among dual diagnosis patients.