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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
N-Acetyl Cysteine for the Treatment of Obsessive Compulsive Disorder (OCD): A Double-Blind, Randomised, Placebo-Controlled Clinical Trial
Scientific title
N-Acetyl Cysteine for the Treatment of Obsessive Compulsive Disorder (OCD)
Secondary ID [1] 282052 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obsessive Compulsive Disorder (OCD) 288526 0
Condition category
Condition code
Mental Health 288857 288857 0 0

Study type
Description of intervention(s) / exposure
N-acetyl cysteine (NAC): 500mg capsules taken orally - 1 capsule twice daily for 1 week, 2 capsules twice daily for the second week and 3 capsules twice daily (3g/day) for the remaining 13 weeks (total 16 weeks).
Intervention code [1] 286664 0
Treatment: Drugs
Comparator / control treatment
Placebo capsules taken in the same manner as the NAC, identical in appearance, which do not contain N-acetyl cysteine or any active component.
Control group

Primary outcome [1] 289013 0
Severity in symptoms will be measured with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS)
Timepoint [1] 289013 0
Reviewed at baseline, week 4, 8, 12 and 16
Secondary outcome [1] 301849 0
Timepoint [1] 301849 0

Key inclusion criteria
Fulfil DSM-IV TR diagnostic criteria for OCD
Self reported OCD will require a diagnosis from a physician
Score 16+ on the Y-BOCS at the time of recruitment
No other treatment, or be on stable treatment i.e. minimum 4 weeks of treatment or minimum of 12 weeks if a new treatment (e.g. SSRI, CBT)
Female participants of child bearing age or sexually active are required to be using effective contraception

Minimum age
18 Years
Maximum age
65 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Known or suspected serious medical disorder i.e. cancer, organ failure
Patients undergoing current psychological programs for their OCD (a four week wash out period will be required for eligibility)
Bipolar I, schizophrenia, epilepsy
Gastrointestinal ulcers
Pregnancy or breastfeeding
History of hypersensitivity or intolerance to NAC
Patients taking 100 micrograms of selenium or 500 IU of vitamin E

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
For potential subjects, a pre screening telephone interview will be completed to assess if they meet the criteria for the trial. If so, they will be invited to meet the clinician at the Melbourne Clinic for a baseline screening interview. By signing a consent form at this interview, which outlines the nature of the trial, and meeting the criteria at the baseline interview, they will become officially enrolled in the research project. The participants will be allocated a number and then randomised into the treatment group or placebo via a computer software program. The clinician will be unaware of which group the participant will be enrolled in. A person outside the project will then code the treatments and maintain the key to this code until data collection is completed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Subjects will be randomised into one of two groups determined by computerised random allocation using their participant number.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Phase 2 / Phase 3
Type of endpoint(s)
Statistical methods / analysis
The primary efficacy analysis will assess average treatment group differences for the primary outcome measure (Y-BOCS) using a mixed-effects model, repeated measures approach (MMRM). Results from the analysis of dichotomous data (e.g. demographics data) will be presented as proportions (e.g. Relative Risks), with 95% confidence interval, and Fisher’s Exact p-value where appropriate. Non-parametric statistics will be used when assumptions for parametric methods are violated. Effect sizes will be calculated using Cohen’s d. All tests of treatment effects will be conducted using a two-sided alpha level of 0.05 and 95% confidence intervals. Data analysed via SPSS 20.0.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 721 0
The Melbourne Clinic - Richmond

Funding & Sponsors
Funding source category [1] 286849 0
Self funded/Unfunded
Name [1] 286849 0
Address [1] 286849 0
Country [1] 286849 0
Primary sponsor type
The Melbourne Clinic
130 Church St Richmond, Melbourne, Victoria, 3121
Secondary sponsor category [1] 285641 0
Commercial sector/Industry
Name [1] 285641 0
Address [1] 285641 0
Unit 16 37-41 O'Riordan St,
Alexandria, NSW
Country [1] 285641 0

Ethics approval
Ethics application status
Ethics committee name [1] 288930 0
The Melbourne Clinic HREC
Ethics committee address [1] 288930 0
130 Church St, Richmond,
VIC, 3121
Ethics committee country [1] 288930 0
Date submitted for ethics approval [1] 288930 0
Approval date [1] 288930 0
Ethics approval number [1] 288930 0

Brief summary
The primary aim of this study is to investigate the efficacy and safety of adjunctive N-acetylcysteine (NAC) in the treatment of adults (n=80) with DSM-IV diagnosed OCD in a 16-week randomised, placebo-controlled trial. The primary outcome will be between group differences the severity of OCD symptoms on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).
Trial website
Trial related presentations / publications
N-Acetyl Cysteine (NAC) in the Treatment of Obsessive-Compulsive Disorder: A 16-Week, Double-Blind, Randomised, Placebo-Controlled Study; Jerome Sarris, Georgina Oliver, David A. Camfield, Olivia M. Dean, Nathan Dowling, Deidre J. Smith, Jenifer Murphy, Ranjit Menon, Michael Berk, Scott Blair-West, Chee H. Ng; CNS Drugs (2015) 29: 801.

Sarris, J., Oliver, G., Camfield, D. A., & Dean, O. M. (2016). Participant characteristics as modifiers of response to N-Acetyl cysteine (NAC) in Obsessive-Compulsive Disorder. Clinical Psychological Science, 4(6), 1104-1111.
Public notes

Principal investigator
Name 38246 0
Dr Jerome Sarris
Address 38246 0
The Melbourne Clinic, 2 Salisbury st, Richmond, VIC, 3121
Country 38246 0
Phone 38246 0
Fax 38246 0
Email 38246 0
Contact person for public queries
Name 38247 0
Miss Gina Oliver
Address 38247 0
The Melbourne Clinic, 2 Salisbury st, Richmond, VIC, 3121
Country 38247 0
Phone 38247 0
+61 3 9487 4659
Fax 38247 0
Email 38247 0
Contact person for scientific queries
Name 38248 0
Miss Gina Oliver
Address 38248 0
The Melbourne Clinic, 2 Salisbury st, Richmond, VIC, 3121
Country 38248 0
Phone 38248 0
+61 3 9487 4659
Fax 38248 0
Email 38248 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary