The efficacy of memantine in Alzheimer’s disease (AD) has been investigated in multiple randomised, placebo-controlled phase III trials. Recently, the indication label for memantine in Europe was extended to cover patients with moderate to severe AD, i.e. Mini-Mental State Exam total scores below 20. The efficacy data for memantine in this patient subgroup has been summarised by a meta-analysis of 1,826 patients in six trials. Efficacy was assessed using measures of global status (Clinician’s Interview-Based Impression of Change Plus Caregiver Input), cognition (Alzheimer’s Disease Assessment Scale – Cognitive Subscale, or Severe Impairment Battery), function (Alzheimer’s Disease Cooperative Study Activities of Daily Living 19- or 23-item scale), and behaviour (Neuropsychiatric Inventory). Results (without replacement of missing values) showed statistically significant effects for memantine (vs. placebo) in each domain. Memantine was well tolerated, and the overall incidence rates of adverse events were comparable to placebo. This meta-analysis supports memantine’s clinically relevant efficacy in patients with moderate to severe AD.

Memantine has a beneficial effect on the behavioural symptoms of patients with moderate to severe AD, with the most pronounced effect on agitation/aggression.

Resource utilisation and total health costs were lower in the memantine group than the placebo group. The results suggest that memantine treatment of patients with moderate to severe AD is cost saving from a societal perspective.

IntroductionMemantine and cholinesterase inhibitors potentially offer additional benefits in Alzheimer's disease (AD) when used together. This study assessed the efficacy and safety of combination treatment with memantine added to stable donepezil in patients with moderate to severe AD, and in a subset with moderate AD.MethodsPost hoc meta-analyses of data combined from two 24-week, randomised, double-blind, placebo-controlled trials of memantine 20 mg/day versus placebo, added to a stable cholinesterase inhibitor, were conducted. Data were included for all patients receiving donepezil 10 mg/day with Mini-Mental State Examination (MMSE) scores < 20 (n = 510). Efficacy was assessed using measures of cognition, function, and global status. Furthermore, marked clinical worsening, defined as concurrent deterioration from baseline in the three main efficacy domains, and safety, measured by treatment-emergent adverse events, were assessed. Analyses were performed for patients with moderate to severe AD (MMSE 5-19; MOD-SEV subgroup), and also for patients with moderate AD (MMSE 10-19; MOD subgroup; n = 367).ResultsAt week 24, in the MOD-SEV subgroup, patients receiving memantine added to donepezil significantly outperformed those receiving placebo added to donepezil in measures of cognition (P < 0.0001), function (P = 0.02), and global status (P = 0.010), with standardised mean differences (SMDs) of 0.36, 0.21, and 0.23, respectively (all last observation carried forward). Similarly, in the MOD subgroup, significant benefits were observed for cognition (P = 0.008), function (P = 0.04) and global status (P = 0.008), with SMDs of 0.28, 0.21, and 0.28, respectively. Significantly fewer patients receiving memantine added to donepezil showed marked clinical worsening than those receiving placebo added to donepezil, in both subgroups (MOD-SEV: 8.7% versus 20.4%, P = 0.0002; MOD: 5.9% versus 15.0%, P = 0.006). The incidence of adverse events was similar between treatment groups.ConclusionsThese results support and extend previous evidence that combination treatment with memantine added to stable donepezil in patients with moderate AD, and in those with moderate to severe AD, is associated with significant benefits in reducing 24-week decline in cognition, function and global status. Combination treatment produces substantially reduced rates of marked clinical worsening, has good safety and tolerability, and generates effect sizes that are both statistically significant and clinically meaningful.

Background/Aims: We aimed to develop realistic definitions of clinical worsening in advanced Alzheimer's disease (AD) and to use them in a post hoc responder analysis of memantine. Methods: 2,340 patients with moderate to severe AD (Mini-Mental State Examination <20) were included from 9 multicentre, 16- to 28-week, randomised, double-blind, placebo-controlled studies of memantine 20 mg/day versus placebo. Responder meta-analyses were performed, with definitions of response based on minimally important differences (MIDs) on cognitive, functional, and global assessment scales. Validated or established MIDs were used where available; otherwise, MIDs were estimated by a data-driven approach, using data from our moderate to severe AD population. Results: Patients with moderate to severe AD treated with memantine had a lower incidence of worsening from baseline to endpoint than patients treated with placebo, in cognition [24.4 vs. 35.0%; odds ratio (OR) = 0.60; p < 0.001], function (38.1 vs. 43.4%; OR = 0.81; p = 0.01), global status (39.8 vs. 48.6%; OR = 0.70; p < 0.001), and in a combined ‘triple' worsening measure (9.4 vs. 16.1%; OR = 0.54; p < 0.001). Conclusions: New definitions of clinical worsening based on MIDs represent a more realistic functional decline in advanced stages of AD. Results of this new analysis show that memantine reduces the incidence of clinical worsening in key symptomatic domains in moderate to severe AD.