Low-dose risperidone as adjunctive therapy for irritable aggression in posttraumatic stress disorder.

Increased aggressive behavior can occur in association with posttraumatic stress disorder (PTSD). This study tested the hypothesis that low-dose risperidone reduces aggression and other PTSD-related symptoms in combat veterans. Subjects were male combat veterans with PTSD who scored 20 or higher on cluster D (hyperarousal) of the Patient Checklist for PTSD-Military Version (PCL-M). Subjects were randomly assigned to either risperidone or placebo treatment groups. Drugs were administered over a 6-week treatment period in a double-blind manner. Subjects received either risperidone (0.5 mg/day; n = 7) or matched placebo (n = 8) tablets during the first 2 weeks of the treatment period. The dose of risperidone could then be increased up to 2.0 mg/day on the basis of response. Prerandomization psychotropic regimens were continued. Subjects were evaluated with the PCL-M and the Overt Aggression Scale-Modified for Outpatients (OAS-M). In comparison with placebo treatment, reductions in scores between baseline and the last week of treatment were significantly greater for OAS-M irritability and PCL-M cluster B (intrusive thoughts) subscales and on the PCL-M total scale. These results suggest that low-dose risperidone administration reduces irritability and intrusive thoughts in combat-related PTSD.