Memantine for patients with Parkinson's disease dementia or dementia with Lewy bodies: a randomised, double-blind, placebo-controlled trial

Background Previous studies have suggested that patients with Lewy-body-related dementias might benefit from treatment with the N-methyl D-aspartate receptor antagonist memantine, but further data are needed. Therefore, the efficacy and safety of memantine were investigated in patients with mild to moderate Parkinson's disease dementia (PDD) or dementia with Lewy bodies (DLB). Methods Patients (>= 50 years of age) with mild to moderate PDD or DLB were recruited from 30 specialist centres in Austria, France, Germany, the UK, Greece, Italy, Spain, and Turkey. They were randomly assigned to placebo or memantine (20 mg per day) according to a computer-generated list. Patients and all physicians who had contact with them were masked to treatment assignment. No primary endpoint was defined. Safety analyses were done for all patients who took at least one dose of memantine or placebo, and efficacy analyses were done for all patients who had at least one valid postbaseline assessment. This trial is registered with ClinicalTrials.gov, number NCT00855686. Findings Of the 199 patients randomly assigned to treatment, 34 with DLB and 62 with PDD were given memantine, and 41 with DLB and 58 with PDD were given placebo. 159 (80%) patients completed the study: 80 in the memantine group and 79 in the placebo group. 93 patients treated with memantine and 97 patients treated with placebo were included in the efficacy analysis. At week 24, patients with DLB who received memantine showed greater improvement according to Alzheimer's disease cooperative study (ADCS)-clinical global impression of change scores than did those who received placebo (mean change from baseline 3.3 vs 3.9, respectively, difference -0.6 [95% CI 1.2 to -0.1]; p=0.023). No significant differences were noted between the two treatments in patients with PDD (3.6 with memantine vs 3.8 with placebo, -0.1 [-0.6 to 0.3]; p=0.576) or in the total population (3.5 with memantine vs 3.8 with placebo, -0.3 [-0.7 to 0.1]; p=0.120). Neuropsychiatric-inventory scores showed significantly greater improvement in the memantine group than in the placebo group (-4.3 vs 1.7, respectively, -5.9 [-11.6 to -0.2]; p=0.041) in patients with DLB, but not in those with PDD (-1.6 vs 0.1, respectively, -1.4 [-5.9 to 3.0]; p=0.522) or in the total patient population (-2.6 vs 0.4, respectively, -2.9 [-6.3 to 0.5]; p=0.092). In most of the cognitive test scores, ADCS-activities of daily living, and Zarit caregiver burden scores, there were no significant differences between the two treatment groups in any of the study populations. The incidence of adverse events and number of discontinuations due to adverse events were similar in the two groups. The most common serious adverse events were stroke (n=3 in memantine group), falls (n=2 in memantine group; n=1 in placebo group), and worsening of dementia (n=2 in memantine group). Interpretation Memantine seems to improve global clinical status and behavioural symptoms of patients with mild to moderate DLB, and might be an option for treatment of these patients.