Memantine add-on to antipsychotic treatment for residual negative and cognitive symptoms of schizophrenia: a meta-analysis

We examined whether memantine add-on to antipsychotic treatment is beneficial in schizophrenia treatment. This systematic review and meta-analysis aimed to achieve stronger evidence on the efficacy and safety of memantine add-on for treating schizophrenia. We analyzed double-blind, randomized, placebo-controlled trials of memantine add-on treatment in schizophrenia patients receiving antipsychotics. The primary outcomes were amelioration of negative symptoms and all-cause discontinuation. Dichotomous outcomes are presented as risk ratios (RRs), and continuous outcomes are presented as mean differences (MDs) or standardized mean differences (SMDs). Eight studies (n = 448) were included. Although memantine add-on treatment was superior to placebo for ameliorating negative symptoms (SMD = −0.96, p = 0.006, I 2 = 88%; N = 7, n = 367) in the Positive and Negative Syndrome Scale general subscale (MD = −1.62, p = 0.002, I 2 = 0%; N = 4, n = 151) and Mini-Mental Status Examination score (MD = −3.07, p