NCT05664789 · Stanford University
Targeting the Neurobiology of RRB in Autism Using N-acetylcysteine: Trial
What this study is about
The goal of this study is to target the neurobiology of restricted and repetitive behaviors in children with autism spectrum disorder using N-acetylcysteine (NAC), a well-tolerated nutritional supplement that has shown promise for reducing symptom severity in recent small-scale trials.
View original scientific description
The goal of this study is to target the neurobiology of restricted and repetitive behaviors in children with autism spectrum disorder using N-acetylcysteine (NAC), a well-tolerated nutritional supplement that has shown promise for reducing symptom severity in recent small-scale trials. The findings from this research will shed light on the mechanisms of action underlying the clinical benefits of NAC and the effects of NAC on altering restricted and repetitive behavior symptom severity in children with autism spectrum disorder. This is a 12-week double-blind, randomized, placebo-controlled trial of NAC.
Interventions
DRUG
N acetyl cysteine
N-acetylcysteine (NAC) is an over-the-counter dietary supplement that is relatively well tolerated and exhibits minimal side effects, even at high dosages. N
DRUG
Placebo
matched placebo
Primary outcome measures
Change in Children's Yale Brown-Obsessive Compulsive Scale for Autism Spectrum Disorder (CYBOCS-ASD) at 12 weeks
Time frame: Screening and week 12
Severity of restricted and repetitive behaviors, higher scores indicate more severe behaviors
Change in Glutamatergic neurometabolites at 12 weeks
Time frame: Baseline and week 12
Glu and Glx measured by magnetic resonance imaging
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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 criteria
- 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
Where
- Palo Alto, California
Collaborators
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 15, 2026 · Source of record for eligibility and locations