CC BY 4.0 Attribution 4.0 InternationalGhaderi, AmirBussu, AnnaTsang, CatherineJafarnejad, Sadegh2025-07-312025-07-312020-10Ghaderi, A., Bussu, A., Tsang, C. and Jafarnejad, S. (2020) ‘Effect of N-acetylcysteine on positive and negative syndrome scale associated with schizophrenia: a meta-analysis’, Reviews in Clinical Medicine, 7(3), p134-144. Available at: https://doi.org/10.22038/rcm.2020.50482.1329.2345-6256https://eresearch.qmu.ac.uk/handle/20.500.12289/14340https://doi.org/10.22038/rcm.2020.50482.1329Catherine Tsang - ORCID: 0000-0003-3102-0373 https://orcid.org/0000-0003-3102-0373Background and objective: N-acetylcysteine (NAC), a precursor of L-cysteine with antioxidant, anti-inflammatory and neurotropic effects, is a promising agent in alleviating symptoms associated with schizophrenia. However, the role of NAC on parameters of Positive and Negative Syndrome Scale (PANSS) remain uncertain. This systematic review and meta-analysis explored the effect of NAC on parameters of PANSS in patients with chronic schizophrenia. Methods: We searchedPubmed/MEDLINE™, PsycNET™, PsycLIT™, Scopus™ and Google Scholar™ for studies on the effect of NAC on PANSS in patients with schizophrenia from inception to March 2019. We adopted medical and non-medical subjects headings (MeSH, non-MeSH) and several keywords, including “NAC”, “N-acetylcysteine”, “N-acetyl cysteine”, “Acetylcysteine”, “N-Acetyl-L-cysteine”, “schizophrenia”, “psychotic disorder”, “psychosis”, “schizoaffective” and “dementia praecox”. Results: We identified seven trials with274 patients meeting the inclusion criteria, with follow up between 8-52 weeks, and NAC supplementation between 1200-3600 mg/day. Significant improvements in PANSS were identified following NAC for total (SMD=-0.61, 95% CI = -0.91, -0.31 ; P<0.001), general (SMD = -0.58; 95% CI = -0.90, -0.26; P=0.0004); and negative (SMD = -0.56; 95% CI = -0.92, -0.21; P = 0.001) scores, respectively. No significant heterogeneity was found among studies. Significant reductions were observed following sub-group analysis in trials ≤ 24 weeks duration, with appreciable effect size for total (SMD= -0.83), general (SMD= -0.67) and negative (SMD=-1.09) scores. Conclusion: Supplementation of NAC was effective in alleviating PANSS symptoms associated with schizophrenia in trials ≤ 24 weeks duration. The use of NAC as an adjunct seems promising and further investigation is warranted to determine its precise role.134-144enIn accordance with the open access principle, the RCM is made accessible to the general public. The approved articles can be read, downloaded, copied, distributed, and shared free as long as the author(s) are attributed. Once the manuscript has been approved, RCM will request the signature of each author on a copyright agreement form to give the required publication rights. Because the author(s) publish their work as open access, some rights, like patents, trademarks, and designs, retain with the author(s), while other copyright is given to the RCM.http://creativecommons.org/licenses/by/4.0/NACPositive and Negative Syndrome Scale (PANSS)SchizophreniaSystematic ReviewRCTsMeta-analysisArticle