A small pilot study (involving 31 children) conducted by the Stanford University School of Medicine has found that an antioxidant supplement may be an effective therapy for some features of autism. The researchers say the antioxidant, called N-Acetylcysteine (NAC), lowered irritability in children with autism as well as reducing the children's repetitive behaviors. NAC could be the first medication available to treat repetitive behavior in autism - if the findings hold up when scrutinized further.
Finding new medications to treat autism and its symptoms is a high priority for researchers. Currently, irritability, mood swings and aggression, all of which are considered associated features of autism, are treated with second-generation antipsychotics. But these drugs cause significant side effects, including weight gain, involuntary motor movements and metabolic syndrome, which increases diabetes risk. By contrast, side effects of NAC are generally mild, with gastrointestinal problems such as constipation, nausea, diarrhea and decreased appetite being the most common.
The study involved children with autism aged from 3 to 12 who received NAC or a placebo for 12 weeks. The subjects were evaluated before the trial began and every four weeks during the study using several standardized surveys that measure problem behaviors, social behaviors, autistic preoccupations and drug side effects.
According to the researchers, NAC treatment decreased irritability scores from 13.1 to 7.2 on the Aberrant Behavior Checklist, a widely used clinical scale for assessing irritability. Although significant, the change is not as large as that seen in children taking antipsychotics.
In addition, according to two standardized measures of autism mannerisms and stereotypic behavior, children taking NAC showed a decrease in repetitive and stereotyped behaviors.
Although the study did not investigate how NAC works, the researchers speculated on two possible mechanisms of action. NAC increases the capacity of the body's main antioxidant network, which some previous studies have suggested is deficient in autism. In addition, other research has suggested that autism is related to an imbalance in excitatory and inhibitory neurotransmitters in the brain. NAC can modulate the glutamatergic family of excitatory neurotransmitters, which might be useful in autism.
Researcher Antonio Hardan cautioned that the NAC for sale as a dietary supplement at grocery stores differs in some important respects from the individually packaged doses of pharmaceutical-grade NAC used in the study, and that the over-the-counter version may not produce the same results. "When you open the bottle from the drugstore and expose the pills to air and sunlight, it gets oxidized and becomes less effective," he said.
Stanford is filing a patent for the use of NAC in autism, and one of the study authors has a financial stake in a company that makes and sells the NAC used in the trial. The scientists are now applying for funding to conduct a large, multicenter trial in which they hope to replicate their findings. "This was a pilot study," Hardan said. "Final conclusions cannot be made before we do a larger trial."
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Source: Stanford University Medical Center