This study will determine the short- and long-term safety and effectiveness of the drug olanzapine (Zyprexa®) for reducing symptoms of autism in children.

Autism is a serious childhood disorder that can significantly impair functioning and development. Educational and psychosocial programs are standard treatments for autistic children, but drug therapy is often needed as well. Haloperidol is the drug most commonly prescribed for symptoms of autism. However, long-term administration of haloperidol has been associated with adverse effects such as blurred vision, constipation, and nausea. The investigation of alternative drug treatments is necessary. This study will determine whether the antipsychotic drug olanzapine may be a safe and effective alternative to haloperidol for treating symptoms of autism in children.

This study will last 36 weeks and will comprise 2 phases. In Phase I, participants will be randomly assigned to receive either olanzapine or placebo for 12 weeks. Participants who do not respond to treatment will complete their participation in the study. Participants who respond to their assigned Phase I treatment will continue onto Phase II. All Phase II participants will receive olanzapine daily for 6 months. Self-report scales and checklists will be used to assess participants after each phase; these measures will be completed by participants and their parents.

Inclusion Criteria:

• Diagnosis of autism
• Parent or guardian willing to provide informed consent

Exclusion Criteria:

• Uncontrolled seizure disorder
• Medical illness other than autism affecting the whole body
• Obesity
• History of psychosis
• Impairment of voluntary movement
• History of olanzapine treatment