N-Acetylcysteine Tablets: In addition to participants' existing medication regimens, NAC will be added.
Placebo Oral Tablet: 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 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.
Eligibility
Sex
ALL
Min age
12 Years
Max age
55 Years
Healthy volunteers
Accepted
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.
Primary outcome measure(s)
Change from Baseline in Neurometabolite Concentrations in Key Brain Regions — 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 — 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.
Trial sites (1)
Facility
City
Region
Status
Guangdong Mental Health Center, Guangdong Provincial People's Hospital
GuangDong
Guangdong
More Guangdong Provincial People's Hospital trials in China
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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