N-acetyl cysteine (NAC) augmentation in Obsessive-Compulsive Disorder (OCD): A 24-week, randomized, double blind placebo controlled trial

University of Melbourne

Dataset description

Dataset derived from a 24-week, multi-centre, randomized, double-blind, placebo-controlled trial evaluating the efficacy of N-acetyl cysteine (NAC) augmentation in the treatment of obsessive-compulsive disorder (OCD). The dataset involves adult participants (18-75 years) with OCD, who are on stable medication dosages for at least 8 weeks prior to the trial. Participants are randomized to receive either NAC (2,000-4,000mg per day) or placebo, with dosages titrated based on response every 4 weeks. The primary outcome measure is the reduction in Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores from baseline. Secondary outcomes include improvements in anxiety, mood, functioning, and overall quality of life.
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FOR: Mental Health |

Source Study




Phase 3


Government body,The National Heath and Medical Research Council

Scientific enquiries

Miss Georgina Oliver

Brief Summary

This study seeks to elucidate the benefits of NAC augmentation (2-4 grams/day) compared to placebo in the treatment of OCD, in a 24-week, multi-centre, randomized, double-blind, placebo controlled trial. It is hypothesized that NAC will be superior over placebo for improving OCD symptoms as measured by a reduction in Y-BOCS scores from baseline against each subsequent time point (W4, W8, W12, W16, W20 and W24). Additional benefits are anticipated for relieving anxiety as well as improving mood, ....
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Key Inclusion Criteria

Primary diagnosis of OCD as per the Structured Interview Guide for the DSM-5 (SCID) Adults between the age of 18-75 who have the desire and capacity to consent to the study and follow its procedures. Minimum score of 16 on the Y-BOCS at time of entry into the study, but no greater than 31. Currently taking medication for their OCD which has been at a stable dose for the past 8-weeks. Stable psychological treatment (if employing) for minimum eight weeks (an 8-week wash-out period will be required ....
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Key Exclusion Criteria

*Bipolar disorder *Psychotic disorders *Primary diagnosis of Obsessive-compulsive spectrum disorders including hoarding, body dysmorphic disorder, trichotillomania (secondary diagnosis permitted) *Severe depression (as defined by HAM-D score equal to or greater than 24 *Alcohol/substance abuse *Y-BOCS score equal to or greater than 32 *Treatment resistant OCD (3 or more trials of first line medications for their OCD at therapeutic doses for minimum of 12-weeks each, at least one augmentation str ....
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Can healthy volunteers participate?




Sample Size    98

Min. age    18 Years

Max. age    75 Years

Sex    Both males and females

Condition category    Obsessive-Compulsive Disorder

Condition code    Mental Health


Intervention code Treatment: Drugs

The amino acid N-acetyl cysteine (NAC; 500mg per capsule, taken orally) or placebo (capsules containing microcellulose), used adjunctive to stable medication (minimum 8-weeks at consistent dosages) for 24 weeks in adults (18-75 years of age) with OCD. Randomised participants will take 2 capsules, twice per day (equating to 2,000mg NAC or placebo per day) for the first 8-weeks of the study. However, the dose of NAC (or placebo) may increase from the week-8 visit. In cases of non-response (<35% re ....
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Control group Placebo

Placebo capsules containing microcellulose


Outcome: Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), clinician administrated (severity scale Q1-Q10 and insight Q11)
Timepoint: Baseline, Week-4, Week-8, Week-12, Week-16, Week-20, Week-24

Will individual participant data (IPD) for this trial be available?


What data in particular will be shared?

-Participant data supporting the publication results -Participant data relating to primary outcomes -Participant safety data

When will data be available?

Data are available straight after publication for an indefinite time

Available to whom?

Data are potentially available to researchers who have obtained ethics approval from a registered HREC to conduct their research. All other data sharing proposals will be assessed on a case by case basis by the study investigators.

Available for what types of analyses?

HREC approved study protocols and IPD meta-analysis or systematic reviews. Other analysis requests will be assessed on a case by case basis by the study investigators.

Source study information is derived from the Australian New Zealand Clinical Trials Registry (ANZCTR). For more information on the ANZCTR, please see