Obsessive Compulsive Disorder (OCD)Phase 4NCT06956157
NAC for Treatment-Resistant OCD and Other Related Disorders
A Phase 4 study testing N-Acetylcysteine Tablets in people with Obsessive Compulsive Disorder (OCD), run by Guangdong Provincial People's Hospital at 1 site in China.
Trial 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). Read more about this study
- Who is it for?
- Ages 12 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Obsessive Compulsive Disorder (OCD)
- What is being tested?
- N-Acetylcysteine Tablets
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 90 participants
- Where
- 1 siteChina
- Study dates
- 22 Jun 2022to 13 Nov 2025
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 55 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
1.Inclusion Criteria for Patient:
(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.
1.2 Inclusion Criteria for Healthy Controls:
(1) Age and sex-matched to the patient group. (2) No personal history of any psychiatric disorder.
1.3 Exclusion Criteria for All Participants: (1) Presence of any contraindications to 3T MRI scanning (e.g., metallic implants, claustrophobia). (2) Current (within the past 6 months) diagnosis of a substance use disorder. (3) Significant or unstable neurological illness (e.g., epilepsy, multiple sclerosis, brain tumor). (4) History of significant head trauma or neurosurgery.
1.4 Additional Exclusion Criteria for Patients with TR-OCD:
(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.
Trial locations and contacts
1 site in 1 country.
China1 site
Guangdong Mental Health Center, Guangdong Provincial People's Hospital
GuangDong, Guangdong, 510120
About this study
Official title: Altered Brain Glutamate Level and Inhibitory Control in Treatment-Resistant Obsessive-Compulsive Disorder After N-acetylcysteine (NAC) Augmentation Therapy
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.
Read the detailed description
Please note: This study was initially designed to investigate the effects of N-acetylcysteine (NAC) across the broader spectrum of treatment-resistant Obsessive-Compulsive and Related Disorders (OCRDs), including cohorts such as Excoriation (Skin-Picking) Disorder. The overarching scientific objective was to use NAC to elucidate the neurobiological mechanisms underlying inhibitory control deficits in this difficult-to-treat population, and thereby inform the development of novel therapeutic strategies.
Upon completion of recruitment for the current analysis phase and prior to any unblinking, we finalized our analytical strategy. To ensure the primary analysis was adequately powered to yield a definitive conclusion, it was focused on the treatment-resistant OCD (TR-OCD) cohort, which comprised the substantial majority of the sample accrued to date.
Consequently, the TR-OCD cohort was designated as the primary population for the main efficacy and mechanistic analyses. Other OCRD subgroups enrolled under the same protocol were designated for planned secondary and exploratory analyses, in line with their respective sample sizes. Analyses of these subgroups, including the SPD cohort, will be conducted once sufficient data have been accrued for robust statistical testing.
This registration has been updated to accurately and transparently reflect this final, pre-specified analytical plan, ensuring the public record aligns with the study's primary, hypothesis-driven conclusions.
- Conditions
- Obsessive Compulsive Disorder (OCD)
- Being tested
- N-Acetylcysteine Tablets, Placebo Oral Tablet
- Medical subject headings
- Obsessive-Compulsive Disorder
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
N-Acetylcysteine TabletsDrug
In addition to participants' existing medication regimens, NAC will be added.
Placebo Oral TabletDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| 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). Receives: Drug: N-Acetylcysteine Tablets |
| Placebo group | Placebo comparator | Not described Receives: Drug: Placebo Oral Tablet |
| Healthy Control Group | No intervention | Not described |
What is being measured
The primary outcome is the main question the study is designed to answer.
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).
Measured: 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.
Measured: Baseline, Post-treatment (Week 12)
Secondary outcomes (2)
Yale-Brown Obsessive Compulsive Scale
Change in the total score of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) from baseline. Scores range from 0 to 40, with higher scores indicating greater symptom severity.
Measured: Baseline, Week 4, Week 8, Week 12
Yale-Brown Obsessive Compulsive Scale modified for Neurotic Excoriation
Proportion of participants achieving a predefined percentage reduction in the total score from baseline to post-treatment.
Measured: Baseline, Week 4, Week 8, Week 12
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 May 2025
- Study start22 Jun 2022
- Primary completion13 Nov 2024
- Study completion13 Nov 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obsessive Compulsive Disorder (OCD)Studies of the same condition, open and under way.
- More trials run by Guangdong Provincial People's HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Guangdong Provincial People's Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, sunnyrong, Guangdong Provincial People's Hospital
- Investigators
- Huirong Zheng, MD, Principal investigator, Guangdong Provincial People's Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06956157
- Sponsor's protocol ID
- KY2020-572
- Other IDs
- 2021A1515011431
- Status last verified
- Sep 2025
- First submitted
- 25 Apr 2025
- Last updated
- 3 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Altered Brain Glutamate Level and Inhibitory Control in Treatment-Resistant Obsessive-Compulsive Disorder After N-acetylcysteine (NAC) Augmentation Therapy
- ClinicalTrials.gov ID
- NCT06956157
- Acronym / sponsor ID
- KY2020-572
- Conditions
- Obsessive Compulsive Disorder (OCD)
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 90 participants (estimated)
- Lead sponsor
- Guangdong Provincial People's HospitalUniversity, hospital or other
- Study start
- 22 Jun 2022 (actual)
- Primary completion
- 13 Nov 2024 (actual)
- Study completion
- 13 Nov 2025 (estimated)
- First posted
- 4 May 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Please note: This study was initially designed to investigate the effects of N-acetylcysteine (NAC) across the broader spectrum of treatment-resistant Obsessive-Compulsive and Related Disorders (OCRDs), including cohorts such as Excoriation (Skin-Picking) Disorder. The overarching scientific objective was to use NAC to elucidate the neurobiological mechanisms underlying inhibitory control deficits in this difficult-to-treat population, and thereby inform the development of novel therapeutic strategies.
Upon completion of recruitment for the current analysis phase and prior to any unblinking, we finalized our analytical strategy. To ensure the primary analysis was adequately powered to yield a definitive conclusion, it was focused on the treatment-resistant OCD (TR-OCD) cohort, which comprised the substantial majority of the sample accrued to date.
Consequently, the TR-OCD cohort was designated as the primary population for the main efficacy and mechanistic analyses. Other OCRD subgroups enrolled under the same protocol were designated for planned secondary and exploratory analyses, in line with their respective sample sizes. Analyses of these subgroups, including the SPD cohort, will be conducted once sufficient data have been accrued for robust statistical testing.
This registration has been updated to accurately and transparently reflect this final, pre-specified analytical plan, ensuring the public record aligns with the study's primary, hypothesis-driven conclusions.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| N-acetylcysteine group | Experimental | Drug: N-Acetylcysteine TabletsNAC (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). |
| Placebo group | Placebo comparator | Drug: Placebo Oral Tablet |
| Healthy Control Group | No intervention | – |
Who may qualify
- Ages
- 12 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| N-Acetylcysteine TabletsIn addition to participants' existing medication regimens, NAC will be added. | Drug | N-acetylcysteine group |
| Placebo Oral TabletPlacebo 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. | Drug | Placebo group |
Primary outcome
Change from Baseline in Neurometabolite Concentrations in Key Brain Regions
Time frame: Baseline, Post-treatment (Week 12)
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).
Change from Baseline in Inhibitory Control Performance
Time frame: Baseline, Post-treatment (Week 12)
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.
2 secondary outcomes
Yale-Brown Obsessive Compulsive Scale
Time frame: Baseline, Week 4, Week 8, Week 12
Yale-Brown Obsessive Compulsive Scale modified for Neurotic Excoriation
Time frame: Baseline, Week 4, Week 8, Week 12
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Sep 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Huirong Zheng, MD principal investigator
Guangdong Provincial People's Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing N-Acetylcysteine Tablets in people with Obsessive Compulsive Disorder (OCD), run by Guangdong Provincial People's Hospital at 1 site in China.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 3 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change from Baseline in Neurometabolite Concentrations in Key Brain Regions (time frame: Baseline, Post-treatment (Week 12)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Sep 2025.