Effects of risperidone on conduct and disruptive behavior disorders in children with subaverage IQs

To determine whether risperidone is effective in reducing symptoms of disruptive behaviors (such as aggression, impulsivity, defiance of authority figures, and property destruction) associated with conduct disorder, oppositional defiant disorder, and disruptive behavior disorder-not otherwise specified in children with subaverage IQs.

The trial consisted of a 1-week, single-blind, placebo run-in period and was followed by a 6-week, double-blind, placebo-controlled period. One hundred ten children (aged 5-12 years inclusive) with an IQ of 36-84 with a disruptive behavior disorder and a score of at least 24 on the Conduct Problem subscale of the Nisonger Child Behavior Rating Form (NCBRF) were enrolled. Eighty percent of subjects had comorbid attention-deficit/hyperactivity disorder (ADHD). Risperidone doses ranged from 0.02 to 0.06 mg/kg per day. Subjects were rated on the NCBRF, Aberrant Behavior Checklist, Behavior Problems Inventory, Clinical Global Impressions (CGI), modified California Verbal Learning Test (CVLT), and a continuous performance task (CPT).

The intention-to-treat analysis of risperidone-treated subjects showed a significant (p < .001) reduction in mean scores (from 33.4 at baseline to 17.6 at end point; 47.3% reduction) versus placebo-treated subjects (mean baseline of 32.6 to 25.8 at end point; 20.9% reduction) on the Conduct Problem subscale of the NCBRF. Between-group differences in favor of risperidone were seen as early as week 1 and were significant at all post-baseline visits. Other subscales showed significant improvement with risperidone compared with placebo. CGI scale ratings of improvement showed highly significant gains for risperidone over placebo. A subanalysis demonstrated that the effect of risperidone was unaffected by diagnosis, presence/absence of ADHD, psychostimulant use, IQ status, and somnolence. Risperidone produced no changes on the cognitive variables (CPT/modified CVLT). The most common side effects included somnolence, headache, appetite increase, and dyspepsia. Side effects related to extrapyramidal symptoms were reported in 7 (13.2%) and 3 (5.3%) of the subjects in the risperidone and placebo groups, respectively (p = .245).

Risperidone appears to be an adequately tolerated and effective treatment in children with subaverage IQs and severe disruptive behaviors such as aggression and destructive behavior.