Recruiting
Phase 2
Phase 3

N-acetylcysteine

Sponsor:

Stanford University

Code:

NCT05664789

Conditions

Autism Spectrum Disorder

Eligibility Criteria

Sex: All

Age: 3 - 12

Healthy Volunteers: Not accepted

Interventions

N acetyl cysteine

Placebo

Study Details

Brief summary:

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.

Conditions

Autism Spectrum Disorder

Study ID

NCT05664789

Start date

Apr 26, 2023

Status verified date

May, 2026

Completion date

Jul 31, 2028

Anticipated

Primary completion date

Jan 31, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 3 - 12

Healthy Volunteers: Not accepted

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

Study Design

Enrollment

144 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

active comparator: N-acetylcysteine

12 week administration of active study compound

placebo comparator: Placebo

12 week administration of matched placebo

Interventions

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

Placebo

matched placebo

Primary outcome measure

  • Change in Children's Yale Brown-Obsessive Compulsive Scale for Autism Spectrum Disorder (CYBOCS-ASD) at 12 weeks [ Time Frame: Screening and week 12 ]
  • Change in Glutamatergic neurometabolites at 12 weeks [ Time Frame: Baseline and week 12 ]

Central Contacts and Locations

Central contacts

Ramy Chebbo

(650)723-7845autismresearch@stanford.edu

John Hegarty, PhD

(650)723-7845autismresearch@stanford.edu

Locations

Department of Psychiatry and Behavioral Sciences

Recruiting

Palo Alto, California, United States, 94304

Contacts

Ramy Chebbo

(650)723-7845autismresearch@stanford.edu

More Information

Sponsor

Stanford University

Last update posted

May 15, 2026

Last verified

May, 2026

Keywords

  • Magnetic resonance imaging
  • N-acetyl cysteine
  • Restricted and repetitive behaviors
  • Electroencephalography

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Stanford University on 2026-05-15.