The antioxidant, N-Acetylcysteine, or NAC, was found to lower irritability in children with autism as well as reduce the children’s repetitive behaviors in a small pilot study. While further, larger studies are necessary; NAC could provide promising support for addressing repetitive behavior in autism. Currently, there is no medication to treat repetitive behavior.
Irritability affects about 70% of children with autism and can hinder learning, as well as other activities and therapies. Currently, irritability, mood swings and aggression, are mostly treated with medication that can have significant side effects such as weight gain, involuntary motor movements and metabolic syndrome. The side effects of NAC are generally mild, with gastrointestinal problems such as constipation, nausea, diarrhea and decreased appetite being the most commonly experienced.
This double-blind pilot study tested children with autism ages 3 to 12. Children received NAC or a placebo for 12 weeks. Subjects were evaluated before the trial began and every 4 weeks during the study using several standardized surveys that measure problem behaviors, social behaviors, autistic preoccupations and drug side effects.
During the 12-week trial, the children given NAC had decreased irritability scores from 13.1 to 7.2 on the Aberrant Behavior Checklist, a widely used clinical scale for assessing irritability. In addition, according to two standardized measures of autism mannerisms and stereotypic behavior, children taking NAC showed a decrease in repetitive and stereotyped behaviors.
Researchers speculate two possible mechanisms. 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.
Hopefully larger trials will support the use of NAC for helping children with autism.