Researchers have found that a specific antioxidant, called N-Acetylcysteine (NAC), may reduce irritability in children with autism.

The pilot trial, conducted by researchers at Stanford University School of Medicine and Lucile Packard Children’s Hospital, involved 31 children aged 3 to 12 years with autism. The study is published in Biological Psychiatry.

The researchers found that NAC reduced irritability and repetitive behaviors of the children. However, before NAC can be recommended for children with autism, larger trials are needed in order to verify results from the pilot trial.

Between 60-70% of children with the disorder suffer from irritability. Antonio Hardan, M.D., an associate professor of psychiatry and behavioral sciences at Stanford and director of the Autism and Developmental Disabilities Clinic at Packard Children’s explained:

“We’re not talking about mild things: This is throwing, kicking, hitting, the child needing to be restrained. It can affect learning, vocational activities and the child’s ability to participate in autism therapies.”

One of the top priorities for researchers is to find new medications to treat autism and its symptoms. At present, aggression, irritability, and mood swings are all associated features of the disorder and are treated with second-generation antipsychotics.

However, these medications cause serious adverse effects including:

  • involuntary motor movements
  • metabolic syndrome – which increases the risk of developing diabetes
  • weight gain

According to the researchers, the side effects of NAC are usually mild. These adverse effects include decreased appetite, diarrhea, constipation, and nausea.

Another major problem of autism is the state of drug treatments for its core features, such as repetitive behaviors, social deficits, and language impairment. Hardan said: “Today, in 2012, we have no effective medication to treat repetitive behavior such as hand flapping or any other core features of autism.”

If results from this trial can be confirmed in larger trials, NAC could be the first drug available to treat repetitive behavior in autism.

The children who participated in the study were physically healthy and had no plans to change their established autism treatments during the trial. The children were given either NAC or placebo for 12 weeks and were assessed before the study and then every 4 weeks during the trial. The researchers used a number or different surveys in order to measure social behaviors, problem behaviors, adverse effects, and autistic preoccupations.

The researchers found that NAC reduced irritability scores from 13.1 to 7.2 on the Aberrant Behavior Checklist, a clinical scale for evaluating irritability. Although, NAC did not reduce irritability as much as antipsychotics, “this is still a potentially valuable tool to have before jumping on these big guns,” said Hardan.

In addition, the team found that NAC also reduced repetitive and stereotyped behaviors in the study participants.

Hardan explained:

“One of the reasons I wanted to do this trial was that NAC is being used by community practitioners who focus on alternative, non-traditional therapies. But there is no strong scientific evidence to support these interventions. Somebody needs to look at them.”

According to Hardan, the NAC used in the trial is different from the NAC for sale as a dietary supplement at pharmacies and grocery stores, and that the over-the-counter version may not produce the same results.

Hardan explained: “When you open the bottle from the drugstore and expose the pills to air and sunlight, it gets oxidized and becomes less effective.”

Even though the team did not examine how NAC works, they believe that it increases the capacity of the body’s main antioxidant network. Furthermore, other studies has indicated that the disorder is associated 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.

Hardan concluded: “This was a pilot study. Final conclusions cannot be made before we do a larger trial.”

Written By Grace Rattue