Effect of N-acetyl cysteine (NAC) supplementation on positive and negative syndrome scale in schizophrenia: a systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE

To conduct a systematic review and meta-analysis of published randomised controlled trials on the efficacy of NAC supplementation on positive and negative syndrome scale in schizophrenia.

METHODS

A meta-analysis was conducted, and studies were identified by a search of electronic databases from inception to May 2018. Combined and stratified analyses were used.

RESULTS

Seven trials were identified, and data from n = 447 participants were included. Pooled analysis showed improvement of positive and negative syndrome scale following NAC treatment compared with placebo, for total (SMB = - 0.96) [95% CI - 1.69, - 0.24; P = 0.009], general (SMB = - 1.04) [95% CI - 1.80, - 0.27; P = 0.008] and negative (SMB = - 0.73) [95% CI - 1.29, - 0.17; P = 0.01] scores, respectively. Significant heterogeneity was found, and subgroup analysis showed significant reductions in studies with a treatment duration of ≤ 24 weeks, with a considerable effect size on total, general, and negative scores (Total SMD = - 0.83; General SMD = - 0.67; Negative SMD = - 1.09) following NAC.

CONCLUSIONS

NAC improved all aspects of positive and negative syndrome scale in schizophrenic populations and may be more efficacious with treatment durations up to 24 weeks.