Efficacy and safety of memantine in adults with amyotrophic lateral sclerosis: a systematic review and meta-analysis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease with limited disease-modifying treatment options. Memantine, an N-methyl-D-aspartate receptor antagonist, has been investigated in ALS, but its safety remains unclear. This study systematically assessed the safety of memantine in adults with ALS. A systematic review and meta-analysis was conducted following PRISMA 2020 guidelines, searching PubMed, Cochrane Library, Scopus, and Web of Science for randomized controlled trials of memantine in adults with ALS. Outcomes included ALSFRS-R and FVC decline, adverse neurological events, total and serious adverse events, treatment discontinuation, and all-cause mortality. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool. Because of heterogeneous reporting and missing variance estimates, ALSFRS-R and FVC outcomes were synthesized narratively; only safety outcomes were pooled quantitatively. Three randomized controlled trials (706 participants) met the inclusion criteria. Functional and respiratory outcomes could not be pooled because of heterogeneous reporting, and no consistent benefit was observed. Memantine showed lower headache incidence than placebo (RR 0.43; 95% CI 0.19-0.96), with no significant differences in constipation, falls, dizziness, treatment discontinuation, or all-cause mortality. Memantine showed a borderline increase in serious adverse events (RR 1.52; 95% CI 1.00-2.31) and a higher risk of total adverse events (RR 1.19; 95% CI 1.09-1.30). Memantine was associated with a small but significant increase in total adverse events and a trend toward more serious adverse events, without improving functional decline, respiratory function, or survival in ALS. Current evidence does not support its use as a disease-modifying or adjunctive therapy. Trial registration: PROSPERO CRD420261277874.