One of a newer class of anti-psychotic medications was successful and well tolerated for the treatment of serious behavioral disturbances associated with autistic disorder in children ages 5 to 17. The findings of the large, multi-site, eight-week, placebo-controlled clinical trial was funded by the National Institute of Mental Health (NIMH).

Autism is a chronic condition that appears in early childhood and is characterized by core symptoms of impaired social relatedness, delayed language, and restricted patterns of behavior. It affects as many as 20 children per 10,000. Although the causes of autism are unknown for most cases, available evidence implicates abnormalities in brain development. Twin and family studies indicate a strong genetic contribution.

In addition to core symptoms, children with autism frequently exhibit serious behavioral disturbances, such as self-injury, aggression, hyperactivity, and tantrums in response to routine environmental demands. For these disturbances, behavioral therapy and medications are the two main forms of treatment.

In this multi-site study, researchers randomly assigned 101 children and adolescents, 82 boys and 19 girls, age 5 to 17, to receive either placebo or risperidone, one of a new class of atypical anti-psychotic medications.

The study found risperidone to be significantly more effective than placebo in improving behavior. Using a stringent definition of improvement, 69 per cent of the children randomly assigned to risperidone were much or very much improved at the end of the study, as compared with only 12 per cent in the placebo group. This is the largest positive effect by a medication ever observed in children with autism.

Risperidone was well tolerated, with few neurological side effects. However, risperidone was associated with a substantial increase in body weight (an average of about a six-pound increase in the 8 week-period).

The atypical anti-psychotic medications are of great interest in treating children with autism because studies have shown them to be beneficial in adults with schizophrenia, with fewer neurological side effects than the older medications.

Few studies of atypical anti-psychotic medications have been conducted in children with autism. The primary goal of this study was to evaluate the efficacy and safety of risperidone, the first widely available atypical anti-psychotic medication, in children with autism accompanied by serious behavioral disturbances.

The study was conducted at five sites of the Research Units of Pediatric Psychopharmacology (RUPP) network, which is funded by NIMH. The RUPP network is composed of research units devoted to conducting studies to test the efficacy and safety of medications commonly used by practitioners to treat children and adolescents (off-label use) but not yet adequately tested.