Objective: This study evaluated the efficacy and safety of naltrexone, an opiate blocker, in the treatment of autism.
Method: Thirteen children with autistic disorder, aged 3.4 to 8.3 years (mean 5.4), were studied in home, school, and outpatient laboratory. Naltrexone, 1.0 mg/kg, was given daily in a randomized, double-blind, placebo-controlled crossover design. Dependent measures included parent and teacher Clinical Global Impressions (CGI), Conners Rating Scales, and Naltrexone Side-Effects (SE) Rating Scale; laboratory CGI, movement actometer readings, and a 10-second interval recording system analysis of on-task, communication initiations, disruptive behavior, and self-stimulation.
Results: Eight of 13 subjects improved in two or more settings. Changes in parent measures (CGI, Conners Impulsivity-Hyperactivity Factor, and SE-Restlessness) and Teacher CGI achieved statistical significance. Teacher SE-Restlessness and initiation of communication in the clinic showed a trend toward improvement. Actometer readings improved in two children who were very active at baseline. Adverse side effects were behavioral, mild, and transient. Administering the bitter tablet was a challenge.
Conclusions: Naltrexone offers promise as an agent for modest improvement of behavior and social communication in young children with autism. Parent and teacher measures can be useful in outpatient trials to evaluate change.