Adjunctive memantine for schizophrenia: a meta-analysis of randomized, double-blind, placebo-controlled trials.

BACKGROUND: Dysfunction of N-methyl-D-aspartate receptor (NMDAR) is involved in the pathophysiology of schizophrenia. A meta-analysis of randomized controlled trials (RCTs) was conducted to examine the efficacy and safety of memantine, a non-competitive NMDAR antagonist, in the treatment of schizophrenia. METHODS: Standardized/weighted mean differences (SMDs/WMDs), risk ratio (RR), and their 95% confidence intervals (CIs) were calculated and analyzed. RESULTS: Included in the meta-analysis were eight RCTs (n = 452) of 11.5 ± 2.6 weeks duration, with 229 patients on memantine (20 mg/day) and 223 patients on placebo. Adjunctive memantine outperformed placebo in the measures of Positive and Negative Syndrome Scale and Brief Psychiatric Rating Scale negative symptoms [SMD: -0.63 (95% CI -1.10 to -0.16), p = 0.009, I 2 = 77%], but not in the total, positive and general symptoms [SMD: -0.46 to -0.08 (95% CI -0.93 to 0.22), p = 0.06-0.60, I 2 = 0-74%] or the Clinical Global Impression Severity Scale [WMD: 0.04 (95% CI -0.24 to 0.32), p = 0.78]. The negative symptoms remained significant after excluding one outlying RCT [SMD: -0.41 (95% CI -0.72 to -0.11), p = 0.008, I 2 = 47%]. Compared with the placebo group, adjunctive memantine was associated with significant improvement in neurocognitive function using the Mini-Mental State Examination (MMSE) [WMD: 3.09, (95% CI 1.77-4.42), p < 0.00001, I 2 = 22%]. There was no significant difference in the discontinuation rate [RR: 1.34 (95% CI 0.76-2.37), p = 0.31, I 2 = 0%] and adverse drug reactions between the two groups. CONCLUSIONS: This meta-analysis showed that adjunctive memantine appears to be an efficacious and safe treatment for improving negative symptoms and neurocognitive performance in schizophrenia. Higher quality RCTs with larger samples are warranted to confirm these findings.

N-acetylcysteine for major mental disorders: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: This systematic review and meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of adjunctive N-acetylcysteine (NAC), an antioxidant drug, in treating major depressive disorder (MDD), bipolar disorder, and schizophrenia. METHODS: The PubMed, Cochrane Library, PsycINFO, CNKI, CBM, and WanFang databases were independently searched and screened by two researchers. Standardized mean differences (SMDs), risk ratios, and their 95% confidence intervals (CIs) were computed. RESULTS: Six RCTs (n = 701) of NAC for schizophrenia (three RCTs, n = 307), bipolar disorder (two RCTs, n = 125), and MDD (one RCT, n = 269) were identified and analyzed as separate groups. Adjunctive NAC significantly improved total psychopathology (SMD = -0.74, 95% CI: -1.43, -0.06; I2 = 84%, P = 0.03) in schizophrenia, but it had no significant effect on depressive and manic symptoms as assessed by the Young Mania Rating Scale in bipolar disorder and only a small effect on major depressive symptoms. Adverse drug reactions to NAC and discontinuation rates between the NAC and control groups were similar across the three disorders. CONCLUSIONS: Adjunctive NAC appears to be a safe treatment that has efficacy for schizophrenia, but not for bipolar disorder or MDD. Further higher quality RCTs are warranted to determine the role of adjunctive NAC in the treatment of major psychiatric disorders.