Violent Behavior in Mental Illness: The Role of Substance Abuse

THAT COMORBID SUBSTANCE USE DISORDERS SUBSTANtially increase the risk for violence in mental illness has been known for decades. However, the prevailing view, based on US and Scandinavian epidemiologic studies, has been that serious mental illness also confers a significant relative risk for violence even in the absence of such comorbidity. Accordingly, a broad clinical consensus has emerged that violence risk management in psychiatric patients with dual diagnoses requires treatment of both the underlying psychopathology and comorbid substance abuse. Recent epidemiologic studies have prompted reexamination of this prevailing view. These new studies report little if any increased risk for violence associated with serious mental illness (such as schizophrenia, bipolar disorder, or major depressive disorder) unless there is comorbidity with substance use disorder. However, there is substantial evidence that substance use comorbidity is only one of several factors that may increase the risk of violent behavior for individuals with severe mental illness. Converging lines of evidence indicate that violence in schizophrenia is heterogeneous in its etiology and manifestation, and that violent behavior can neither be fully understood nor successfully managed without specifying different causal pathways and perhaps types of that behavior. Thus, attempts to characterize a general relationship between violence and mental disorder are inherently inadequate, both conceptually and empirically. Emerging evidence suggests that irrespective of comorbidity with substance abuse disorder, at least 2 alternative pathways to violence may occur in patients with schizophrenia: one pathway that is associated with a history of long-standing antisocial behavior problems typically beginning in childhood, and another pathway without such history. Antipsychotic medications may do little to reduce risk for the first type of violence, but may be highly effective in reducing the second type, which is more related to acute psychotic symptoms. Along these same lines, factor analysis has suggested etiological subtypes of violence in psychiatric inpatients. The first (antisocial) pathway is consistent with the literature on comorbidity between schizophrenia and personality disorder. For individuals with schizophrenia complicated by substance abuse disorder, there may be several pathways to violent behavior. Acute pharmacological effects of alcohol and certain drugs such as cocaine can increase violence risk. In patients with underlying mental illness, pharmacological effects of alcohol and other substances may increase inherent violence risk by exacerbating psychiatric symptoms. Specifically, violence may become much more likely when substance abuse is added to the combinations of impaired impulse control and symptoms such as hostility, threat perception, grandiosity, and dysphoria. Substance use disorders are also associated with treatment nonadherence, which is well known to increase the risk for violence in outpatients with serious mental illness. Several general criminogenic mechanisms can lead to violence, independently or in tandem with substance abuse. For example, illicit drug trade occurs typically in the poorest neighborhoods or in predatory social environments in which respect is achieved by violence. Criminogenic mechanisms underlying violence in patients with schizophrenia and comorbid drug abuse disorders have been little studied. Most discussions of violence risk in relation to serious mental illness and substance abuse pertain to patients living in the community. However, violent behavior also occurs on secure wards of psychiatric inpatient facilities. Some persistently violent inpatients may have a history of substance abuse, but inpatient violence can persist months or years after ingested alcohol or drugs have been metabolized. Continued access to illicit substances on inpatient wards is unlikely. The fact that violent behavior in psychotic inpatients responds to antipsychotic medications, particularly clozapine, makes it unlikely that such violence occurring on closed wards can be explained by substance abuse or that it could be prevented by substance abuse treatment. Such treatment, however, should be provided to inpatients with