A double-blind, placebo-controlled study of the efficacy of transdermal clonidine in autism

Autistic individuals often exhibit hyperarousal behaviors (e.g., stereotyped body movements, self-stimulation, hypervigilance, and hyperactivity). Clonidine, an alpha 2-adrenergic receptor agonist, has been shown to be effective in reducing impulsivity, inattention, and hyperactivity associated with attention deficit disorder with hyperactivity. This study investigated the efficacy and safety of transdermal clonidine in reducing hyperarousal behaviors associated with autism.

A double-blind, placebo-crossover study with transdermal clonidine was performed in nine autistic males (aged 5 to 33 years). Subjects received either clonidine (approximately 0.005 mg/kg/day) or placebo by a weekly transdermal patch. Each trial lasted 4 weeks with a 2-week washout period between treatment phases. Subjects were evaluated every 2 weeks by clinician raters and weekly by parents.

The clonidine treatment showed a significant difference from placebo treatment on three subscales of the Ritvo-Freeman Real Life Rating Scale (i.e., social relationship to people, affectual responses, and sensory responses). The Clinical Global Impressions scale indicated that clonidine produced a significant improvement on severity of illness, global improvement, and efficacy index for therapeutic effect of the drug. A patient global rating scale showed clonidine treatment resulted in significant improvement in comparison with placebo. Adverse effects included sedation and fatigue during the first 2 weeks of clonidine treatment.

Results from this preliminary study show that clonidine was effective in reducing several hyperarousal behaviors and improved social relationships in some autistic subjects. Further studies are needed in a larger autistic population to determine the dose-response relationship of clonidine.