A Randomized, Placebo-Controlled, Blinded, Crossover, Pilot Study of the Effects of Dextromethorphan/Quinidine for the Treatment of Neurobehavioral Symptoms in Adults with Autism

Prior studies have demonstrated successful irritability treatment using dopaminergic antagonists in autistic patients. The purpose of this pilot study was to assess the effect of dextromethorphan/quinidine (DM/Q) in autistic adults (18–60 years of age). This was a randomized, blinded, crossover, study of 14 patients randomized to DM/Q or a placebo for 8 weeks, washed out for 4 weeks, then crossed over to the opposite treatment. There were no serious adverse events. Subjects were significantly lower on the Aberrant Behavioral Checklist for Irritability (ABC-IR) (F 1,10 = 7.42; p = 0.021). Improvements in aggression and Clinical Global Impression were also seen. The findings suggest that DM/Q is well-tolerated and associated with improvements in irritability and aggression in adults with autism.