Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 12 2 2017 04 23 134 141 EN Ahmad Ghanizadeh Research Center for Psychiatry and Behavioral Sciences, Shiraz University of MedicalSciences, Shiraz, Iran Mohammad Reza Mohammadi Psychiatry and Psychology Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran Department of Psychiatry, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran Shahla Bahraini . Research Center for Psychiatry and Behavioral Sciences, Shiraz University of Medical Sciences, Shiraz, Iran - Department of Psychiatry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Zahra Keshavarzi Psychiatry and Psychology Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran Ali Firoozabadi Research Center for Psychiatry and Behavioral Sciences, Shiraz University of Medical Sciences, Shiraz, Iran - Department of Psychiatry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Ali Alavi Shoshtari Research Center for Psychiatry and Behavioral Sciences, Shiraz University of Medical Sciences, Shiraz, Iran - Department of Psychiatry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 2017 04 22 Objective: Glutamate is considered a target for treating obsessive-compulsive disorder (OCD). The efficacy and safety of the nutritional supplement of N-Acetylcysteine (NAC) as an adjuvant to serotonin reuptake inhibitor (SSRI) for treating children and adolescents with OCD has never been examined. Methods: This was a 10-week randomized double-blind placebo-controlled clinical trial with 34 OCD outpatients. The patients received citalopram plus NAC or placebo. Yale-Brown Obsessive-Compulsive Scale (YBOCS) and Pediatric Quality of Life Inventory (PedsQL™) were used. Adverse effects were monitored. Results: YBOCS score was not different between the two groups at baseline, but the score was different between the two groups at the end of this trial (P<0.02). The YBOCS score of NAC group significantly decreased from 21.0(8.2) to 11.3(5.7) during this study. However, no statistically significant decrease of YBOCS was found in the placebo group. The Cohen’s d effect size was 0.83. The mean change of score of resistance/control to obsessions in the NAC and placebo groups was 1.8(2.3) and 0.8(2.1), respectively (P = 0.2). However, the mean score of change for resistance/control to compulsion in the NAC and placebo groups was 2.3(1.8) and 0.9(2.3), respectively. Cohen’s d effect size was 0.42. The score of three domains of quality of life significantly decreased in N-Acetylcysteine group during this trial. However, no statistically significant decrease was detected in the placebo group. No serious adverse effect was found in the two groups. Conclusion: This trial suggests that NAC adds to the effect of citalopram in improving resistance/control to compulsions in OCD children and adolescents. In addition, it is well tolerated. https://ijps.tums.ac.ir/index.php/ijps/article/view/1040 https://ijps.tums.ac.ir/index.php/ijps/article/download/1040/617