Olanzapine versus haloperidol in children with autistic disorder: an open pilot study

Conventional neuroleptics ameliorate symptoms in children with autistic disorder; however, they are known to cause dyskinesias. Atypical neuroleptics, including olanzapine, may have less risk for dyskinesia, but their efficacy in autistic disorder is not established. This study was designed to investigate the safety and effectiveness of open-label olanzapine as a treatment for children with autistic disorder by using haloperidol as a standard comparator treatment.

In a parallel groups design, 12 children with DSM-IV autistic disorder (mean age 7.8+/-2.1 years) were randomized to 6 weeks of open treatment with olanzapine or haloperidol. Mean final dosages were 7.9+/-2.5 mg/day for olanzapine and 1.4+/-0.7 mg/day for haloperidol. Outcome measures included the Clinical Global Impressions (CGI) and the Children's Psychiatric Rating Scale (CPRS).

Both groups had symptom reduction. Five of six in the olanzapine group and three of six in the haloperidol group were rated as responders according to the CGI Improvement item. Subjects showed improvement on the CPRS Autism Factor (F1,9 = 24.4, p = .0008). Side effects included drowsiness and weight gain.

The findings suggest that olanzapine is a promising treatment for children with autistic disorder. Further placebo-controlled and long-term studies of olanzapine in autistic disorder are required.