Fluoxetine treatment of children and adults with autistic disorder and mental retardation.

An open trial of pharmacological treatment with fluoxetine, ranging from 20 mg every other day to 80 mg per day, led to a significant improvement in Clinical Global Impressions ratings of Clinical Severity in 15 of 23 subjects with autistic disorder and 10 of 16 subjects with mental retardation. Six of 23 patients with autistic disorder and 3 of 16 patients with mental retardation had side effects which significantly interfered with function, consisting predominantly of restlessness, hyperactivity, agitation, decreased appetite, or insomnia. Double-blind studies of the efficacy of pharmacological agents that potently inhibit 5-HT uptake in the treatment of mental retardation coexisting with Axis I psychiatric disorders (especially obsessive-compulsive disorder) and autistic disorder are warranted.