Risk and Prevention of Aggression in Patients With Psychotic Disorders

Aggression is an important negative outcome, and its prediction and prevention are among the top priorities in psychosis care. In their contribution in this issue of the Journal, Krakowski et al. (1) compare the effects of antipsychotics on violent schizophrenia patients with and without comorbid conduct disorder. As expected, patients with a history of comorbid conduct disorders had more frequent and severe physical assaults compared with patients without conduct disorders. Interestingly, clozapine and olanzapine had more pronounced antiaggressive effects compared with haloperidol in patients with conduct disorders than in patients without this comorbidity. We put this new, important finding into perspective.

The exact magnitude of the problem at hand is not completely clear because studies use different definitions, methods, populations, and settings. In a 38-year follow-up study that included the total population in Sweden, the adjusted odds ratio for convictions of any violent offense—including homicide, sexual offenses, assault, and intimidation—in patients with psychotic disorders (N=24,297) was 7.4 (95% CI=7.1–7.8) compared with the general population (2). A recent study in two U.K. regions that used police data of patients with first-episode psychosis (N=177) found that 14.7% were arrested or charged for violent offenses within 12 months after their first contact with specialized mental health care (3). In contrast to increased rates of violence, patients with psychotic disorders are also more vulnerable for victimization. A meta-analysis found that 20% of patients with psychotic disorders reported violent victimization over a 3-year period, some five times higher than in the general community (4). For a national census in Norway, mental health clinicians performed an unstructured risk assessment on inpatients and outpatients in psychiatric treatment, which included 60%−65% of all patients. Risk was rated as none, low to moderate, high, or very high. Results showed that 7% of outpatients and 27% of inpatients were considered to be at low to moderate risk and that 5% of inpatients and less than 1% of outpatients were at high or very high risk (5). These risk assessments are considerably lower than the actual odds ratio for violent offenses, indicating a gap between estimated risk and actual occurrence of violence, yet reliable identification of patients at risk is crucial in the prevention of aggression. Several recent studies present interesting findings on risk factors.

First, a 6-year follow-up study of patients with psychotic disorders confirmed earlier studies that childhood trauma is a risk factor for aggression (hazard ratio=1.74, 95% CI=1.03–2.93) (6). Another important and well-known childhood risk factor, conduct disorder, was confirmed in the article by Krakowski et al. (1). Interestingly, Oakley et al. (7) found that conduct disorder was associated with childhood adversities and with later violence among a sample of 54 male patients with schizophrenia. The authors therefore suggested that there is a complex interplay between childhood adversity, conduct disorder, and later violent behavior in psychotic disorders (7).

Second, substance abuse has long been confirmed as an important risk factor for aggression. Lamsma et al. (8) synthesized two nationwide psychosis studies from the United Kingdom and the Netherlands. Compared with nondaily or no illicit drug use, daily use of cannabis (pooled odds ratio=1.6, 95% CI=1.2–2.0), stimulants (pooled odds ratio=2.8, 95% CI=1.7–4.5), and sedatives (opiates and inhalants) (pooled odds ratio=2.2, 95% CI=1.1–4.5) all increased the risk for violence (8). Kalk et al. (9) analyzed data of first-time admitted patients in an emergency psychiatric detention facility in the United Kingdom (N=1,089) and found that psychotic symptoms combined with recent cannabinoid use largely increased the risk for aggression (odds ratio=7.1, 95% CI=3.7–13.6). The risk was also increased, but to a lesser extent, among patients without psychotic symptoms but with recent use of both cannabinoids and stimulants (odds ratio=3.3, 95% CI=1.4–7.9).

Third, results from a cohort study in Switzerland that included patients with first-episode psychosis (N=265) confirmed that impulsivity increased the risk for violence (odds ratio=1.53, 95% CI=1.22–1.93), although not spectacularly. This relationship was not mediated by substance abuse (10). In more chronic psychotic disorders, 26% of the safety needs related to aggression were attributable to impulsivity 3 years earlier, assuming causality (6).

Fourth, Buchanan et al. (11) recently analyzed data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial, in which patients with schizophrenia (N=1,435) were followed for 18 months, and found that medication nonadherence was related to injurious violence (hazard ratio=1.39, 95% CI=1.04–1.86). Other risk factors in this study included recent violent victimization (hazard ratio=3.52, 95% CI=1.62–7.64) and severity of illicit drug abuse (hazard ratio=2.93, 95% CI=1.65–5.18).