Memantine and Cognition in Parkinson's Disease Dementia/Dementia With Lewy Bodies: A Meta-Analysis

Background: The aim of this work was to utilize meta-analysis in examining the effects of memantine on neuropsychological functioning in patients with Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB). Methods: Included studies fulfilled these criteria: included objective cognitive measures, a comparison group of participants not taking memantine, and provided sufficient data for calculation of effect size. We examined effect sizes across global cognition and five specific neuropsychological domains. Moderator variables examined included neuropsychological domain, diagnostic cohort (PDD, DLB, or mixed PDD-DLB cohort), study design (open label or placebo-controlled), and trial length. Results: Six publications met inclusion criteria totaling 57 effects. Homogeneity analysis across cognitive domains revealed a small overall effect size (d = 0.25) that was significantly heterogeneous (P < 0.001). Specific neuropsychological domains did not moderate effect size, though. Moderator analysis studies using a mix of DLB and PDD subjects showed larger effects than those that included DLB or PDD patients only. Additionally, open-label trials had significantly (P < 0.001) larger effect sizes (d = 1.32) than placebo-controlled trials (d = 0.12). Conclusions: The present study indicates that effect-size heterogeneity across studies of memantine in DLB and PDD patients is moderated by diagnostic makeup of the cohort and study design. The small overall effect size noted in placebo-controlled trials versus open-label trials indicates that memantine has minimal effects on cognition in PDD and DLB and is unlikely to demonstrate clinically significant improvements in cognition.