The short-term benefit of risperidone in ameliorating severe disruptive behavior in pediatric patients with autism spectrum disorders is well established; however, only one placebo-controlled, long-term study of efficacy is available.

Thirty-six children with an autism spectrum disorder (5-17 years old) accompanied by severe tantrums, aggression, or self-injurious behavior, started 8-week open-label treatment with risperidone. Responders (n = 26) continued treatment for another 16 weeks, followed by a double-blind discontinuation (n = 24; two patients discontinued treatment because of weight gain) consisting of either 3 weeks of taper and 5 weeks of placebo only or continuing use of risperidone. Relapse was defined as a significant deterioration of symptoms based on clinical judgment and a parent questionnaire.

Risperidone was superior to placebo in preventing relapse: this occurred in 3 of 12 patients continuing on risperidone versus 8 of 12 who switched to placebo (p = .049). Weight gain, increased appetite, anxiety, and fatigue were the most frequently reported side effects.

This study indicates the effectiveness of risperidone during a period of several months, reducing disruptive behavior in about half of the children with autism spectrum disorders. The results provide a rationale for the continuing use of risperidone beyond 6 months, although considerable weight gain can limit the use of this agent.