This study is designed to determine the effectiveness of risperidone, a drug treatment for
the interfering symptoms of Autistic Disorder in children and adolescents between the ages of
5 and 17. Between 100 and 120 patients will be participating in this research study at five
academic medical centers in the United States. The primary aim of the treatment is to reduce
impairing behavioral symptoms such as aggression, explosive outbursts, or self-injurious
behavior, without significant side effects. A secondary aim is to evaluate possible
improvement in the level of social relatedness, attention, motor coordination, and short-term
memory.
This study is a placebo-controlled, double-blind study (neither the investigators nor
patients know if the treatment being given is risperidone or an inactive substance, placebo).
Patients will be asked to participate for 6 to 8 months. For the first 8 weeks, patients will
receive either risperidone or placebo, randomly chosen. At the end of the 8 weeks, those
patients who have improved and were on risperidone will be asked to continue on this
medication for another 4 months. The last two months of the study are again double-blind
(neither patients nor investigators know treatment). Patients will either continue
risperidone treatment or be gradually tapered from risperidone (placebo-substitution). This
blinded discontinuation phase will last 2 months during which patients will be closely
monitored for recurrence or worsening of symptoms. Patients who have been treated with
placebo in the first 8 weeks of the study and have not improved will be treated with
risperidone. Weekly visits are required for the first 8 weeks of the study, monthly visits
for the following 4 months, and weekly visits during the last 2 months of the study.