Autism is a developmental disorder that affects a person’s ability to communicate and socialize with others. One of its hallmarks is irritability, which affects 60 to 70 percent of all children with the disorder. “We’re not talking about mild things,” notes Antonio Hardan, MD, associate professor of psychiatry and behavioral science at Stanford University. “This is throwing, kicking, hitting or the child needing to be restrained. It can affect learning, vocational activities and the child’s ability to participate in autism therapies.”

Commonly, autistic children are given antipsychotic drugs to help manage their symptoms. But during a new study at Stanford University, Harden and his research team found that a widely used antioxidant called N-acetylcysteine (NAC) may safely help soothe irritability and repetitive behaviors in some children with the disorder. 

The study, which appeared in the June 1, 2012, issue of Biological Psychiatry, tested 31 children between the ages of 3 and 11 who had previously been diagnosed with autism. Each of the participants was evaluated before the study began, and then every four weeks thereafter, using standardized tests that measure social and behavioral problems, autistic preoccupations and side effects. During the 12-week study, each child received either a placebo or 900 mg of NAC once a day for four weeks, twice a day for another four weeks, and then three times a day for the final four weeks. 

By the end of the study the researchers found that those taking NAC showed a significant improvement in irritability and aggression compared to those given a placebo. They also showed a marked decrease in repetitive behavior. One reason may be due to NAC’s ability to maintain and restore levels of glutathione, a key antioxidant that helps protect brain cells. NAC may also help balance certain neurotransmitters involved in behavior. And unlike antipsychotic drugs, which can cause weight gain, involuntary motor movements and metabolic syndrome, NAC has few side effects.