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N-acetylcysteine for Restricted and Repetitive Behaviors in Autism

This study is looking into whether N-acetylcysteine (NAC), a common dietary supplement, can help reduce restricted and repetitive behaviors in children with Autism Spectrum Disorder (ASD). NAC is generally well-tolerated and has shown some promise in smaller studies. The researchers want to understand how NAC works and if it can lessen these behaviors. You may be able to join if you are a child between 3 and 12 years old with a confirmed diagnosis of ASD and at least moderate restricted and repetitive behaviors. The study will measure changes in these behaviors and brain chemicals over 12 weeks to see if NAC is effective. The current status of this study is unclear.

Study design
This is a 12-week study that will compare N-acetylcysteine (NAC) to a placebo (an inactive substance). It is designed as a double-blind, randomized, placebo-controlled trial, meaning neither you nor the study team will know if you are receiving NAC or the placebo.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
The study will measure changes in behaviors and brain chemicals at 12 weeks after the start of the study.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05664789

Targeting the Neurobiology of RRB in Autism Using N-acetylcysteine: Trial

Recruiting
PHASE2Ages 3–12InterventionalTreatment
Stanford University
~144 participants
Updated 2026-05-15 on ClinicalTrials.gov
What's tested:N acetyl cysteinePlacebo

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Change in Children's Yale Brown-Obsessive Compulsive Scale for Autism Spectrum Disorder (CYBOCS-ASD) at 12 weeks
Measured over Screening and week 12
+1 more outcome measured

Conditions

Autism Spectrum Disorder

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Autism Spectrum Disorder

NCT05664789

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Department of Psychiatry and Behavioral Sciences

    Palo Alto, Californiastudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • John Hegarty, PhD · PRINCIPAL_INVESTIGATOR · Stanford University

Who to contact

Ramy Chebbo
[email protected]
(650)723-7845
Email the study team

Opens a ready-to-send draft in your own email app — review before sending.

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Eligibility criteria

Inclusion

children between 3 years and 12 years 11 months
diagnosis of autism spectrum disorder confirmed with the Autism Diagnostic Interview- Revised and the Autism Diagnostic Observation Schedule-2, Brief Observation of Symptoms of Autism, or Childhood Autism Rating Scale
at least moderate severity of restricted and repetitive behaviors defined by a Children's Yale-Brown Obsessive Compulsive Scale for Autism Spectrum Disorder score ≥ 11
physical development indicative of prepubescence as defined by criteria for Tanner Stage 1
if home address is within 300 miles of the primary study site, participants must pass MR safety screening (e.g., no metal in the body) and attempt baseline neuroimaging (MRI or EEG), otherwise baseline neuroimaging is not required for participation
have stable medication regimens (≥ 30 days) and psychosocial treatments (≥ 60 days) prior to randomization with no anticipated changes during the trial

Exclusion

presence of known genetic abnormalities associated with ASD (e.g. Fragile X)
current or life-time diagnosis of severe psychiatric disorder (e.g., schizophrenia)
presence of significant medical problems
the inability of at least one caregiver to speak and read English to a sufficient level
participants taking glutathione agents/prodrugs
history of any adverse effects to glutathione agents/prodrugs
the inability to drink a sample study compound dissolved in liquid

What this trial measures

  • Change in Children's Yale Brown-Obsessive Compulsive Scale for Autism Spectrum Disorder (CYBOCS-ASD) at 12 weeksScreening and week 12

    Severity of restricted and repetitive behaviors, higher scores indicate more severe behaviors

  • Change in Glutamatergic neurometabolites at 12 weeksBaseline and week 12

    Glu and Glx measured by magnetic resonance imaging