NAC for Treatment-Resistant OCD and Other Related Disorders

NCT06956157 | Active Not Recruiting Phase 4

• 2 other identifiers: KY2020-5722021A1515011431
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

This is a randomized, double-blind, placebo-controlled study investigating N-acetylcysteine (NAC) as an augmentation therapy for individuals with treatment-resistant obsessive-compulsive disorder (TR-OCD), studied within a broader cohort of treatment-resistant Obsessive-Compulsive and Related Disorders (OCRDs). The study's primary aim is to investigate the neurobiological mechanism by which NAC improves inhibitory control deficits in TR-OCD. This is achieved by using Magnetic Resonance Spectroscopy (MRS) to measure changes in thalamic glutamatergic metabolism. A secondary aim is to assess the clinical efficacy of this augmentation strategy on symptom severity. The central hypothesis is that improvements in inhibitory control are mediated by NAC-induced changes in brain glutamate levels.

Conditions

Obsessive Compulsive Disorder (OCD)

Outcome Measures

Primary Outcomes (2)

• Change from Baseline in Neurometabolite Concentrations in Key Brain Regions

  Change from baseline to Week 12 in the concentrations of Glutamate (Glu), Glutamate+Glutamine (Glx), and Glutathione (GSH) within two pre-specified regions of interest: the thalamus and the anterior cingulate cortex (ACC). Levels are measured in both resting and functional states using Magnetic Resonance Spectroscopy (MRS).

  Baseline, Post-treatment (Week 12)

• Change from Baseline in Inhibitory Control Performance

  Change from baseline to Week 12 in inhibitory control performance, as measured by the error rate on a Go-Nogo task. A decrease in the error rate indicates improvement.

  Baseline, Post-treatment (Week 12)

Secondary Outcomes (2)

• Yale-Brown Obsessive Compulsive Scale

  Baseline, Week 4, Week 8, Week 12

• Yale-Brown Obsessive Compulsive Scale modified for Neurotic Excoriation

  Baseline, Week 4, Week 8, Week 12

Study Arms (3)

N-acetylcysteine group

EXPERIMENTAL

NAC (N-Acetylcysteine Tablets, brand name: Flumucil) has a drug specification of 600 mg per tablet. In the first week, participants took 1200mg/d (one tablet three times daily: morning, noon, and evening). Starting from the second week until the end of the 12-week study, they took 3600mg/d (three tablets twice daily: morning and evening).

Drug: N-Acetylcysteine Tablets

Placebo group

PLACEBO COMPARATOR

Drug: Placebo Oral Tablet

Healthy Control Group

NO INTERVENTION

Interventions

N-Acetylcysteine Tablets DRUG

In addition to participants' existing medication regimens, NAC will be added.

N-acetylcysteine group

Placebo Oral Tablet DRUG

Placebo oral tablets are identical in appearance (size, shape, color), packaging, taste, and administration schedule to the N-Acetylcysteine tablets to maintain blinding. The tablets contain inert excipients and no active pharmacological ingredients.

Placebo group

Eligibility Criteria

• Age: 12 Years - 55 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• (1) Age between 12 and 55 years. (2) A primary diagnosis of OCD according to DSM-5 criteria. (3) Excoriation (Skin-Picking) Disorder (SPD) according to DSM-5 criteria.
• (4) Met criteria for treatment resistance, defined as: (a) A Y-BOCS score ≥ 16. (b) A history of inadequate response (\<25% reduction in Y-BOCS score) to at least two different serotonin reuptake inhibitors (SSRIs) at an adequate dose for at least 12 weeks each.
• (1) Age and sex-matched to the patient group. (2) No personal history of any psychiatric disorder.

You may not qualify if:

• (1) Current or lifetime diagnosis of a primary psychotic disorder (e.g., schizophrenia), bipolar I/II disorder, or intellectual disability. (2) Any contraindication to the use of N-acetylcysteine.

Sponsors & Collaborators

• Guangdong Provincial People's Hospital: lead

Study Sites (1)

Guangdong Mental Health Center, Guangdong Provincial People's Hospital

GuangDong, Guangdong, 510120, China

Location

MeSH Terms

Conditions

Obsessive-Compulsive Disorder

Interventions

Acetylcysteine

Condition Hierarchy (Ancestors)

Anxiety Disorders; Mental Disorders

Intervention Hierarchy (Ancestors)

Cysteine; Amino Acids, Sulfur; Sulfur Compounds; Organic Chemicals; Amino Acids; Amino Acids, Peptides, and Proteins

Study Officials

• Huirong Zheng, MD

  Guangdong Provincial People's Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Director

Study Record Dates

• First Submitted: April 25, 2025
• First Posted: May 4, 2025
• Study Start: June 22, 2022
• Primary Completion: November 13, 2024
• Study Completion: November 13, 2025
• Last Updated: September 3, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)