N-Acetylcysteine in Depressive Symptoms and Functionality: A Systematic Review and Meta-Analysis

Objective: To assess the utility of N-acetylcysteine administration for depressive symptoms in subjects with psychiatric conditions using a systematic review and meta-analysis.

Data Sources: A computerized literature search was conducted in MEDLINE, Embase, the Cochrane Library, SciELO, PsycINFO, Scopus, and Web of Knowledge. No year or country restrictions were used. The Boolean terms used for the electronic database search were (NAC OR N-acetylcysteine OR acetylcysteine) AND (depression OR depressive OR depressed) AND (trial). The last search was performed in November 2014.

Study Selection: The literature was searched for double-blind, randomized, placebo-controlled trials using N-acetylcysteine for depressive symptoms regardless of the main psychiatric condition. Using keywords and cross-referenced bibliographies, 38 studies were identified and examined in depth. Of those, 33 articles were rejected because inclusion criteria were not met. Finally, 5 studies were included.

Data Extraction: Data were extracted independently by 2 investigators. The primary outcome measure was change in depressive symptoms. Functionality, quality of life, and manic and anxiety symptoms were also examined. A full review and meta-analysis were performed. Standardized mean differences (SMDs) and odds ratios (ORs) with 95% CIs were calculated.

Results: Five studies fulfilled our inclusion criteria for the meta-analysis, providing data on 574 participants, of whom 291 were randomized to receive N-acetylcysteine and 283 to placebo. The follow-up varied from 12 to 24 weeks. Two studies included subjects with bipolar disorder and current depressive symptoms, 1 included subjects with MDD in a current depressive episode, and 2 included subjects with depressive symptoms in the context of other psychiatric conditions (1 trichotillomania and 1 heavy smoking). Treatment with N-acetylcysteine improved depressive symptoms as assessed by Montgomery-Asberg Depression Rating Scale and Hamilton Depression Rating Scale when compared to placebo (SMD = 0.37; 95% CI = 0.19 to 0.55; P < .001). Subjects receiving N-acetylcysteine had better depressive symptoms scores on the Clinical Global Impressions-Severity of Illness scale at follow-up than subjects on placebo (SMD = 0.22; 95% CI = 0.03 to 0.41; P < .001). In addition, global functionality was better in N-acetylcysteine than in placebo conditions. There were no changes in quality of life. With regard to adverse events, only minor adverse events were associated with N-acetylcysteine (OR = 1.61; 95% CI = 1.01 to 2.59; P = .049).

Conclusions: Administration of N-acetylcysteine ameliorates depressive symptoms, improves functionality, and shows good tolerability.