Cognitive Response to Memantine in Moderate to Severe Alzheimer Disease Patients Already Receiving Donepezil

The Biology and Pathobiology of Glutamatergic, Cholinergic, and Dopaminergic Signaling in the Aging Brain

The elderly population is growing worldwide, with important health and socioeconomic implications. Clinical and experimental studies on aging have uncovered numerous changes in the brain, such as decreased neurogenesis, increased synaptic defects, greater metabolic stress, and enhanced inflammation. These changes are associated with cognitive decline and neurobehavioral deficits. Although aging is not a disease, it is a significant risk factor for functional worsening, affective impairment, disease exaggeration, dementia, and general disease susceptibility. Conversely, life events related to mental stress and trauma can also lead to accelerated age-associated disorders and dementia. Here, we review human studies and studies on mice and rats, such as those modeling human neurodegenerative diseases, that have helped elucidate (1) the dynamics and mechanisms underlying the biological and pathological aging of the main projecting systems in the brain (glutamatergic, cholinergic, and dopaminergic) and (2) the effect of defective glutamatergic, cholinergic, and dopaminergic projection on disabilities associated with aging and neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. Detailed knowledge of the mechanisms of age-related diseases can be an important element in the development of effective ways of treatment. In this context, we briefly analyze which adverse changes associated with neurodegenerative diseases in the cholinergic, glutaminergic and dopaminergic systems could be targeted by therapeutic strategies developed as a result of our better understanding of these damaging mechanisms.

The Role of Glutamate in Language and Language Disorders - Evidence from ERP and Pharmacologic Studies

Current models of language processing do not address mechanisms at the neurotransmitter level, nor how pharmacologic agents may improve language function(s) in seemingly disparate disorders. L-Glutamate, the primary excitatory neurotransmitter in the human brain, is extensively involved in various higher cortical functions. We postulate that the physiologic role of L-Glutamate neurotransmission extends to the regulation of language access, comprehension, and production, and that disorders in glutamatergic transmission and circuitry contribute to the pathogenesis of neurodegenerative diseases and sporadic-onset language disorders such as the aphasic stroke syndromes. We start with a review of basic science data pertaining to various glutamate receptors in the CNS and ways that they may influence the physiological processes of language access and comprehension. We then focus on the dysregulation of glutamate neurotransmission in three conditions in which language dysfunction is prominent: Alzheimer's Disease, Fragile X-associated Tremor/Ataxia Syndrome, and Aphasic Stroke Syndromes. Finally, we review the pharmacologic and electrophysiologic (event related brain potential or ERP) data pertaining to the role glutamate neurotransmission plays in language processing and disorders.

Combination Drug Therapy for the Management of Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia worldwide. Even though the number of AD patients is rapidly growing, there is no effective treatment for this neurodegenerative disorder. At present, implementation of effective treatment approaches for AD is vital to meet clinical needs. In AD research, priorities concern the development of disease-modifying therapeutic agents to be used in the early phases of AD and the optimization of the symptomatic treatments predominantly dedicated to the more advanced AD stages. Until now, available therapeutic agents for AD treatment only provide symptomatic treatment. Since AD pathogenesis is multifactorial, use of a multimodal therapeutic intervention addressing several molecular targets of AD-related pathological processes seems to be the most practical approach to modify the course of AD progression. It has been demonstrated through numerous studies, that the clinical efficacy of combination therapy (CT) is higher than that of monotherapy. In case of AD, CT is more effective, mostly when started early, at slowing the rate of cognitive impairment. In this review, we have covered the major studies regarding CT to combat AD pathogenesis. Moreover, we have also highlighted the safety, tolerability, and efficacy of CT in the treatment of AD.

Memantine for dementia

BACKGROUND

Memantine is a moderate affinity uncompetitive antagonist of glutamate NMDA receptors. It is licensed for use in moderate and severe Alzheimer's disease (AD); in the USA, it is also widely used off-label for mild AD.

OBJECTIVES

To determine efficacy and safety of memantine for people with dementia. To assess whether memantine adds benefit for people already taking cholinesterase inhibitors (ChEIs).

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's register of trials (http://www.medicine.ox.ac.uk/alois/) up to 25 March 2018. We examined clinical trials registries, press releases and posters of memantine manufacturers; and the web sites of the FDA, EMEA and NICE. We contacted authors and companies for missing information.

SELECTION CRITERIA

Double-blind, parallel group, placebo-controlled, randomised trials of memantine in people with dementia.

DATA COLLECTION AND ANALYSIS

We pooled and analysed data from four clinical domains across different aetiologies and severities of dementia and for AD with agitation. We assessed the impact of study duration, severity and concomitant use of ChEIs. Consequently, we restricted analyses to the licensed dose (20 mg/day or 28 mg extended release) and data at six to seven months duration of follow-up, and analysed separately results for mild and moderate-to-severe AD.We transformed results for efficacy outcomes into the difference in points on particular outcome scales.

MAIN RESULTS

Across all types of dementia, data were available from almost 10,000 participants in 44 included trials, most of which were at low or unclear risk of bias. For nearly half the studies, relevant data were obtained from unpublished sources. The majority of trials (29 in 7885 participants) were conducted in people with AD.1. Moderate-to-severe AD (with or without concomitant ChEIs). High-certainty evidence from up to 14 studies in around 3700 participants consistently shows a small clinical benefit for memantine versus placebo: clinical global rating (CGR): 0.21 CIBIC+ points (95% confidence interval (CI) 0.14 to 0.30); cognitive function (CF): 3.11 Severe Impairment Battery (SIB) points (95% CI 2.42 to 3.92); performance on activities of daily living (ADL): 1.09 ADL19 points (95% CI 0.62 to 1.64); and behaviour and mood (BM): 1.84 Neuropsychiatric Inventory (NPI) points (95% CI 1.05 to 2.76). There may be no difference in the number of people discontinuing memantine compared to placebo: risk ratio (RR) 0.93 (95% CI 0.83 to 1.04) corresponding to 13 fewer people per 1000 (95% CI 31 fewer to 7 more). Although there is moderate-certainty evidence that fewer people taking memantine experience agitation as an adverse event: RR 0.81 (95% CI 0.66 to 0.99) (25 fewer people per 1000, 95% CI 1 to 44 fewer), there is also moderate-certainty evidence, from three additional studies, suggesting that memantine is not beneficial as a treatment for agitation (e.g. Cohen Mansfield Agitation Inventory: clinical benefit of 0.50 CMAI points, 95% CI -3.71 to 4.71) .The presence of concomitant ChEI does not impact on the difference between memantine and placebo, with the possible exceptions of the BM outcome (larger effect in people taking ChEIs) and the CF outcome (smaller effect).2. Mild AD (Mini Mental State Examination (MMSE) 20 to 23): mainly moderate-certainty evidence based on post-hoc subgroups from up to four studies in around 600 participants suggests there is probably no difference between memantine and placebo for CF: 0.21 ADAS-Cog points (95% CI -0.95 to 1.38); performance on ADL: -0.07 ADL 23 points (95% CI -1.80 to 1.66); and BM: -0.29 NPI points (95% CI -2.16 to 1.58). There is less certainty in the CGR evidence, which also suggests there may be no difference: 0.09 CIBIC+ points (95% CI -0.12 to 0.30). Memantine (compared with placebo) may increase the numbers of people discontinuing treatment because of adverse events (RR 2.12, 95% CI 1.03 to 4.39).3. Mild-to-moderate vascular dementia. Moderate- and low-certainty evidence from two studies in around 750 participants indicates there is probably a small clinical benefit for CF: 2.15 ADAS-Cog points (95% CI 1.05 to 3.25); there may be a small clinical benefit for BM: 0.47 NOSGER disturbing behaviour points (95% CI 0.07 to 0.87); there is probably no difference in CGR: 0.03 CIBIC+ points (95% CI -0.28 to 0.34); and there may be no difference in ADL: 0.11 NOSGER II self-care subscale points (95% CI -0.35 to 0.54) or in the numbers of people discontinuing treatment: RR 1.05 (95% CI 0.83 to 1.34).There is limited, mainly low- or very low-certainty efficacy evidence for other types of dementia (Parkinson's disease and dementia Lewy bodies (for which CGR may show a small clinical benefit; four studies in 319 people); frontotemporal dementia (two studies in 133 people); and AIDS-related Dementia Complex (one study in 140 people)).There is high-certainty evidence showing no difference between memantine and placebo in the proportion experiencing at least one adverse event: RR 1.03 (95% CI 1.00 to 1.06); the RR does not differ between aetiologies or severities of dementia. Combining available data from all trials, there is moderate-certainty evidence that memantine is 1.6 times more likely than placebo to result in dizziness (6.1% versus 3.9%), low-certainty evidence of a 1.3-fold increased risk of headache (5.5% versus 4.3%), but high-certainty evidence of no difference in falls.

AUTHORS' CONCLUSIONS

We found important differences in the efficacy of memantine in mild AD compared to that in moderate-to-severe AD. There is a small clinical benefit of memantine in people with moderate-to-severe AD, which occurs irrespective of whether they are also taking a ChEI, but no benefit in people with mild AD.Clinical heterogeneity in AD makes it unlikely that any single drug will have a large effect size, and means that the optimal drug treatment may involve multiple drugs, each having an effect size that may be less than the minimum clinically important difference.A definitive long-duration trial in mild AD is needed to establish whether starting memantine earlier would be beneficial over the long term and safe: at present the evidence is against this, despite it being common practice. A long-duration trial in moderate-to-severe AD is needed to establish whether the benefit persists beyond six months.

The Alzheimer's Disease Clinical Spectrum: Diagnosis and Management

Alzheimer's disease (AD) care requires timely diagnosis and multidisciplinary management. Evaluation involves structured patient and caregiver history and symptom-function reviews, examination, and testing (laboratory and neuroimaging) to delineate impairment level, determine the cognitive-behavioral syndrome, and diagnose cause. Clinical biomarkers are available to aid high confidence in etiologic diagnosis. Management uses psychoeducation, shared goal setting, and patient-caregiver dyad decision making. When combined, pharmacologic and nonpharmacologic therapies mitigate symptoms and reduce clinical progression and care burden. AD biopathologic processes develop over decades before symptoms manifest; this period is increasingly targeted in research as an opportunity to best delay or prevent AD dementia.

Using linked administrative and disease-specific databases to study end-of-life care on a population level

BACKGROUND

The use of full-population databases is under-explored to study the use, quality and costs of end-of-life care. Using the case of Belgium, we explored: (1) which full-population databases provide valid information about end-of-life care, (2) what procedures are there to use these databases, and (3) what is needed to integrate separate databases.

METHODS

Technical and privacy-related aspects of linking and accessing Belgian administrative databases and disease registries were assessed in cooperation with the database administrators and privacy commission bodies. For all relevant databases, we followed procedures in cooperation with database administrators to link the databases and to access the data.

RESULTS

We identified several databases as fitting for end-of-life care research in Belgium: the InterMutualistic Agency's national registry of health care claims data, the Belgian Cancer Registry including data on incidence of cancer, and databases administrated by Statistics Belgium including data from the death certificate database, the socio-economic survey and fiscal data. To obtain access to the data, approval was required from all database administrators, supervisory bodies and two separate national privacy bodies. Two Trusted Third Parties linked the databases via a deterministic matching procedure using multiple encrypted social security numbers.

CONCLUSION

In this article we describe how various routinely collected population-level databases and disease registries can be accessed and linked to study patterns in the use, quality and costs of end-of-life care in the full population and in specific diagnostic groups.

Oleanolic acid ameliorates cognitive dysfunction caused by cholinergic blockade via TrkB-dependent BDNF signaling

Oleanolic acid is a naturally occurring triterpenoid and is widely present in food and medicinal plants. To examine the effect of oleanolic acid on memory deficits, we employed a cholinergic blockade-induced cognitive deficit mouse model. A single administration of oleanolic acid significantly increased the latency on the passive avoidance task and affected the alternation behavior on the Y-maze task and the exploration time on the novel object recognition task, indicating that oleanolic acid reverses the cognitive impairment induced by scopolamine. In accordance with previous reports, oleanolic acid enhanced extracellular-signal-regulated kinase 1/2 (ERK1/2) and cAMP response element-binding protein (CREB) phosphorylation and brain-derived neurotrophic factor (BDNF) expression in the hippocampus. Interestingly, ameliorating effect of oleanolic acid on scopolamine-induced memory impairment was abolished by N2-(2-{[(2-oxoazepan-3-yl)amino]carbonyl}phenyl)benzo[b]thiophene-2-carboxamide (ANA-12), a potent and specific inhibitor of tropomyosin receptor kinase B (TrkB), in the passive avoidance task. Similarly, oleanolic acid significantly evoked long-term potentiation in a dose-dependent manner, which was diminished by ANA-12 treatment as shown in the electrophysiology study. Together, these results imply that oleanolic acid ameliorates scopolamine-induced memory impairment by modulating the BDNF-ERK1/2-CREB pathway through TrkB activation in mice, suggesting that oleanolic acid would be a potential therapeutic agent for the treatment of cognitive deficits.

Benefits and risks of add-on therapies for Alzheimer's disease

Despite three decades of intensive research, the efforts of scientific society and industry and the expenditures, numerous attempts to develop effective treatments for Alzheimer's disease have failed. Currently, approved and widely used medications to treat cognitive deficits in Alzheimer's disease are symptomatic only and show at best modest efficacy. In this context, the need to develop a successful, disease-modifying treatment is loudly expressed. One way to achieve this goal is the use of add-on therapies or various combinations of existing ‘conventional’ drugs. Results of several clinical studies and post hoc analyses of combination therapy with all cholinesterase inhibitors and memantine are published. Moreover, there is a need for studies on long-term efficacy of combination therapy in Alzheimer's.

The effects of combine treatment of memantine and donepezil on Alzheimer's disease patients and its relationship with cerebral blood flow in the prefrontal area

BACKGROUND

In this study, we evaluated the effect on cognitive function of memantine, behavioral and psychological symptoms of dementia, and the care burden, in patients with moderate-to-severe Alzheimer's disease (AD). Furthermore, with near-infrared spectroscopy (NIRS), we examined the association between effect of memantine and brain blood flow.

METHODS

We evaluated the effect of memantine administration from baseline on Clinical Global Impression-Improvement scale, mini mental state examination (MMSE), Clock Drawing Test (CDT), Neuropsychiatric Inventory (NPI), Japanese version of the Zarit Burden Interview (J-ZBI) and NIRS in two groups, donepezil administration memantine combination group (combination group, n = 19) donepezil administration memantine non-administration group (control group, n = 18) were assessed at weeks 0, 4, 12, and 24.

RESULTS

Significant difference was found between the combination group and the control group in the score variation of Clinical Global Impression-Improvement scale, MMSE, CDT, NPI, and J-ZBI. In the NIRS measurements, trend oxyhemoglobin reduced suppression was observed in some channels centered on the superior frontal gyrus. A significant correlation was observed in the scores of MMSE, CDT, NPI, and J-ZBI. In addition, a significant positive correlation was also observed between the number of words in NIRS and scores of MMSE and CDT.

CONCLUSIONS

In this study, by administering memantine in AD patients that inhibit the reduction of cerebral blood flow in the prefrontal area and improve clinical symptoms overall cognitive function, behavioral and psychological symptoms of dementia, thereby reducing the care burden of caregivers was suggested.

Efficacy and safety of memantine in patients with moderate-to-severe Alzheimer's disease: results of a pooled analysis of two randomized, double-blind, placebo-controlled trials in Japan

BACKGROUND

With the increase in the aging population, there is a pressing need to provide effective treatment options for individuals with Alzheimer's disease (AD). Memantine is an N-methyl-D-aspartate receptor antagonist used to treat AD in > 80 countries worldwide, and studies in the USA and Europe have shown it to be effective in improving language deficits; however, there are currently no data on language improvements in Japanese patients treated with memantine.

OBJECTIVES

To clarify the efficacy and safety of memantine in Japanese outpatients with moderate to severe AD, using a pooled analysis of two multicenter randomized placebo-controlled trials, a phase 2 dose-finding study and a phase 3 study.

RESULTS

The final analysis comprised 633 patients (318 receiving memantine and 315 placebo). Memantine produced better outcomes in terms of Severe Impairment Battery-Japanese version, Clinician's Interview-Based Impression of Change plus-Japanese version, Behavioral Pathology in AD Rating Scale, and language scores, versus placebo. The overall incidence of adverse events and adverse reactions was similar between groups.

CONCLUSION

In this pooled analysis of Japanese patients, memantine achieved better outcomes than placebo in terms of cognition, including attention, praxis, visuospatial ability and language, and behavioral and psychological symptoms, including activity disturbances and aggressiveness.

Rivastigmine in moderately severe-to-severe Alzheimer's disease: Severe Impairment Battery factor analysis

Introduction

The Severe Impairment Battery (SIB) is validated for assessing cognition in patients with severe dementia. The current analysis aimed to further investigate the cognitive efficacy of rivastigmine capsules, as assessed by SIB factor scores, in patients with moderately severe-to-severe Alzheimer’s disease (AD).

Methods

This was a retrospective analysis of a 26-week, multicenter, randomized, double-blind, placebo-controlled study of oral rivastigmine conducted in Spain. Previously reported outcome measures included the full SIB. Current analyses examined calculated scores and effect sizes for the change from baseline at Week 26 on: newly defined SIB subscales (derived by a factor analysis of the 40 SIB items, using the PROC FACTOR function (SAS)); previously defined memory, language and praxis subscales (derived by previous analysis of the nine SIB domains); and the individual SIB items. Treatment differences were assessed.

Results

SIB data were provided by 104 rivastigmine-treated patients and 106 patients receiving placebo (Intent-To-Treat Last Observation Carried Forward population). Significantly less decline was observed on the previously defined memory and language subscales, and the newly defined working memory/memory subscale in rivastigmine-treated patients (all P < 0.05 versus placebo). Calculation of effect sizes demonstrated numerically greater efficacy of rivastigmine versus placebo on each of the subscales, and a broad range of SIB items; greatest effect sizes were observed on SIB items assessing the current month (effect size = 0.30) and digit span series (effect size = 0.33).

Conclusions

These data suggest the observed efficacy of rivastigmine in moderately severe-to-severe AD is likely a cumulative effect across a range of tasks. Rivastigmine demonstrates broad cognitive efficacy in this patient population.

Efficacy of memantine, donepezil, or their association in moderate-severe Alzheimer's disease: a review of clinical trials

Background. Acetylcholinesterase (AChE)/cholinesterase (ChE) inhibitors (Is) and memantine are licensed for symptomatic treatment of mild-moderate and moderate-severe forms of Alzheimer's disease (AD), respectively. High doses of the AChE-I donepezil were licensed in the USA for moderate-severe AD, and the association AChE/ChE-Is plus memantine was proposed for AD at this stage. Objectives. This paper has reviewed evidence from clinical trials of the effectiveness of memantine, donepezil, or the two drugs in association in managing moderate-severe AD. Method. Double-blind, placebo-controlled randomized trials (RCTs) using memantine or donepezil alone or in association versus placebo in moderate-severe AD were reviewed. Analysis done in January 2013 considered the years 2007–2012. Results and Conclusion. Only 83 of the 941 papers selected were considered relevant, and only 13 met the criterion of “adequacy and representativeness.” Memantine and donepezil lead to improvements in moderate-to-severe AD and the choice between the compounds should be based on their contraindications more than on disease severity. No evidence was found of advantages of the association of memantine-donepezil. The heterogeneity of conditions explored by RCTs, the relatively short time of observation (24–52 weeks), and the different cognitive assessment tools used did not allow comparing properly different trials.

Pharmacological modulation of cognitive and behavioral symptoms in patients with dementia due to Alzheimer's disease

To evaluate correlations of pharmacological treatment with cognitive and behavioral symptoms in patients with dementia due to Alzheimer's disease with low schooling, subjects were assessed for demographic features, neuropsychiatric symptoms, cognitive decline, functionality, caregiver burden, APOE haplotypes and pharmacological treatment. Among 217 patients, use of cholinesterase inhibitors with or without Memantine was associated with less neuropsychiatric symptoms, while anti-psychotics and/or anti-epileptic drugs were associated with lower instrumental functionality. Anti-psychotics were also associated with more neuropsychiatric symptoms in moderately impaired patients, possibly reflecting the greater need for such treatment when behavioral symptoms are present. Patients receiving more medications were usually younger, obese, married, with higher schooling and more neuropsychiatric symptoms. APOE4+ haplotypes were correlated with earlier dementia onset, but not with pharmacological treatment. Higher caregiver burden was associated with more psychotropic drugs. A trend was found for treatment with cholinesterase inhibitors and Memantine to be associated with longer lengths of dementia for moderately impaired but not for severely impaired patients, regardless of APOE haplotypes, translating into a synergistic effect among such medications for slowing cognitive decline but not for prolonging survival. Further longitudinal studies may be required to assess dose-response relationships regarding treatment with psychotropics for patients with dementia.

Aspects of communication in Alzheimer's disease: clinical features and treatment options

BACKGROUND

During the course of Alzheimer's disease (AD), cognitive processes, including language and communication, become increasingly impaired. The aim of this review was to highlight the impact of communication deficits in AD, and discuss the need for effective treatments.

METHOD

PubMed was searched for studies relating to language and communication in AD. The publications identified were used as a basis for the commentary in this paper. Studies relating to the clinical effectiveness of pharmacological treatment for language and communication issues were identified systematically.

RESULTS

Communication deficits are common in AD. From the earliest disease stage, the patient's capacity for communication declines as problems develop with the use of language and all aspects of functional communication. There is a loss of the ability to communicate thoughts and needs, and it becomes increasingly difficult to interact socially and sustain personal relationships with caregivers, family, and friends. It is unsurprising that patients become frustrated at their loss of self-expression, and studies have demonstrated that impaired communication is strongly linked with the development of significant behavioral concerns. Overall, poor communication contributes to caregiver strain, and adds notably to the burden of disease. Clinical data and post-hoc analyses provide preliminary indications that anti-AD therapies (memantine and the cholinesterase inhibitors, ChEIs) and non-pharmacological cognitive-linguistic stimulation techniques may be helpful in addressing communication difficulties.

CONCLUSIONS

The capacity to treat or slow the progression of communication deficits in AD would prolong patient independence, and have a profound impact on the quality of life of patients and caregivers. The use of pharmacological (anti-AD therapies) and non-pharmacological (cognitive-linguistic stimulation) treatments may be useful management methods and warrant further investigation.

Memantine and cholinesterase inhibitors: complementary mechanisms in the treatment of Alzheimer's disease

This review describes the preclinical mechanisms that may underlie the increased therapeutic benefit of combination therapy-with the N-methyl-D-aspartate receptor antagonist, memantine, and an acetylcholinesterase inhibitor (AChEI)-for the treatment of Alzheimer's disease (AD). Memantine, and the AChEIs target two different aspects of AD pathology. Both drug types have shown significant efficacy as monotherapies for the treatment of AD. Furthermore, clinical observations indicate that their complementary mechanisms offer superior benefit as combination therapy. Based on the available literature, the authors have considered the preclinical mechanisms that could underlie such a combined approach. Memantine addresses dysfunction in glutamatergic transmission, while the AChEIs serve to increase pathologically lowered levels of the neurotransmitter acetylcholine. In addition, preclinical studies have shown that memantine has neuroprotective effects, acting to prevent glutamatergic over-stimulation and the resulting neurotoxicity. Interrelations between the glutamatergic and cholinergic pathways in regions of the brain that control learning and memory mean that combination treatment has the potential for a complex influence on disease pathology. Moreover, studies in animal models have shown that the combined use of memantine and the AChEIs can produce greater improvements in measures of memory than either treatment alone. As an effective approach in the clinical setting, combination therapy with memantine and an AChEI has been a welcome advance for the treatment of patients with AD. Preclinical data have shown how these drugs act via two different, but interconnected, pathological pathways, and that their complementary activity may produce greater effects than either drug individually.

Effects of donepezil 23 mg on Severe Impairment Battery domains in patients with moderate to severe Alzheimer's disease: evaluating the impact of baseline severity

INTRODUCTION

The US Food and Drug Administration approved a 23 mg daily dose of donepezil for treatment of moderate to severe Alzheimer's disease (AD) based on outcomes from a large trial comparing the 23 mg/day dose with the standard 10 mg/day dose. Results from this study indicated that after 24 weeks, donepezil 23 mg/day provided significant cognitive benefits over donepezil 10 mg/day, measured using the Severe Impairment Battery (SIB). In the analyses reported herein, we further characterize the range of cognitive domains impacted by treatment with donepezil 23 mg/day.

METHODS

A post hoc analysis was conducted using data from a 24-week, randomized, double-blind trial comparing donepezil 23 mg/day versus 10 mg/day in 1,467 patients with moderate to severe AD (baseline Mini-Mental State Examination (MMSE) score 0 to 20). Changes from baseline to week 24 in the nine SIB domain scores were analyzed in the intent-to-treat (ITT) population (baseline MMSE 0 to 20), in patients with more severe baseline AD (MMSE 0 to 16), and in severity strata based on baseline MMSE scores (0 to 5, 6 to 10, 11 to 15, 16 to 20).

RESULTS

In the ITT population, changes in six of the nine SIB domains favored donepezil 23 mg/day over donepezil 10 mg/day. LS mean treatment differences were significant for the language, visuospatial ability, and construction domains. In the more advanced cohort of patients (MMSE 0 to 16 at baseline), LS mean treatment differences were statistically significant favoring donepezil 23 mg/day in five of the nine domains: language, memory, visuospatial ability, attention, and construction. Descriptive analysis of LS mean changes in SIB domain scores in the four baseline severity strata showed variable patterns of response; overall, cognitive benefits of donepezil 23 mg/day were greatest in patients with MMSE scores of 0 to 15.

CONCLUSIONS

These results suggest that donepezil 23 mg/day provides benefits over 10 mg/day across a range of cognitive domains. The magnitude of benefit and domains impacted varied depending on the stage of AD; significant benefits with higher dose donepezil were most apparent at more advanced stages of AD and were most prominent in the language domain.

Memantine in patients with Alzheimer's disease receiving donepezil: new analyses of efficacy and safety for combination therapy

Introduction

Memantine 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.

Methods

Post 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).

Results

At 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.

Conclusions

These 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.

Recommended measures for the assessment of cognitive and physical performance in older patients with dementia: a systematic review

Aim/Goal

To recommend a set of neuropsychological and physical exercise tests for researchers to assess cognition and physical fitness in clinical trials with older patients with dementia; to create consensus, decrease heterogeneity, and improve research quality.

Methods

A literature search (2005–2011) yielded 89 randomized controlled trials. To provide information on test recommendations the frequency of test use, effect size of the test outcome, study quality, and psychometric properties of tests were analyzed.

Results

Fifty-nine neuropsychological tests (cognitive domains: global cognition, executive functioning, memory, and attention) and 10 exercise tests (physical domains: endurance capacity, muscle strength, balance, and mobility) were found.

Conclusion

The Severe Impairment Battery, Mini Mental State Examination, and Alzheimer Disease Assessment Scale – cognitive subscale were recommended to measure global cognition. The Verbal Fluency Test Category/Letters, Clock Drawing Test, and Trail Making Test-B were recommended to measure executive functioning. No specific memory test could be recommended. The Digit Span Forward, Digit Span Backward, and Trail Making Test-A were recommended to measure attention. As physical exercise tests, the Timed Up and Go and Six Meter Walk for mobility, the Six Minute Walk Distance for endurance capacity, and the Tinetti Balance Scale were recommended.

Efficacy and safety of donepezil 23 mg versus donepezil 10 mg for moderate-to-severe Alzheimer's disease: a subgroup analysis in patients already taking or not taking concomitant memantine

BACKGROUND/AIMS

A large multicenter trial of donepezil 23 mg/day versus donepezil 10 mg/day for moderate-to-severe Alzheimer's disease allowed patients taking concomitant memantine. We evaluated the efficacy/safety of donepezil 23 and 10 mg/day in this trial, with respect to concomitant memantine use.

METHODS

Prespecified analysis of data from a 24-week, randomized, double-blind trial. Patients were randomized to donepezil doses (23 vs. 10 mg/day) and stratified by concomitant memantine use (yes or no). Efficacy and safety were assessed for each donepezil dose in subgroups taking or not taking concomitant memantine.

RESULTS

At week 24, donepezil 23 mg/day provided significant cognitive benefits over 10 mg/day (p < 0.01) on the Severe Impairment Battery, with or without concomitant memantine (ANCOVA adjusted for baseline score, country and treatment). The higher dose showed no benefit on the global function, Mini-Mental State Examination or activities of daily living measures in either memantine subgroup. Rates of treatment-emergent adverse events (AEs) were higher for donepezil 23 mg/day with memantine (80.7%) than 23 mg/day without memantine (69.7%) or 10 mg/day with/without memantine (66.7/62.0%); across all treatment groups, most events were mild/moderate in severity. Individual rates of serious AEs were low (<1.0%), regardless of concomitant memantine use.

CONCLUSION

In this population, concomitant memantine use did not alter the response profile of donepezil 23 vs. 10 mg/day. Donepezil 23 mg was generally safe and well tolerated among patients receiving donepezil alone and among patients receiving a combination of donepezil and memantine therapy.

Benefits of combined cholinesterase inhibitor and memantine treatment in moderate-severe Alzheimer's disease

BACKGROUND

Clinical studies and post hoc analyses have investigated the use of combination therapy for the treatment of Alzheimer's disease (AD). We review the evidence for the short- and long-term efficacy of combination therapy in AD.

METHODS

The review is based on a search of the PubMed database to identify relevant articles concerning combination treatment with memantine and cholinesterase inhibitors (ChEIs).

RESULTS

In patients with moderate-to-severe AD, combination treatment with the N-methyl-d-aspartate receptor antagonist memantine and the ChEI donepezil has produced significant benefits in cognition, function, behavior, global outcome, and care dependency, compared with donepezil treatment alone. Data from long-term observational studies support these findings. Compared with ChEI monotherapy, combination treatment slowed cognitive and functional decline (a 4-year sustained effect that appeared to increase over time) and reduced the risk of nursing home admission. Preclinically, the combination of N-methyl-d-aspartate receptor modulation and acetylcholinesterase inhibition has been shown to act synergistically, which may explain the observed clinical effects of combination treatment.

CONCLUSION

Treatment with memantine/ChEI combination therapy in moderate-to-severe AD produces consistent benefits that appear to increase over time, and that are beyond those of ChEI treatment alone.

N-methyl D-aspartate (NMDA) receptor antagonists and memantine treatment for Alzheimer's disease, vascular dementia and Parkinson's disease

Memantine, a partial antagonist of N-methyl-D-aspartate receptor (NMDAR), approved for moderate to severe Alzheimer's disease (AD) treatment within the U.S. and Europe under brand name Namenda (Forest), Axura and Akatinol (Merz), and Ebixa and Abixa (Lundbeck), may have potential in alleviating additional neurological conditions, such as vascular dementia (VD) and Parkinson's disease (PD). In various animal models, memantine has been reported to be a neuroprotective agent that positively impacts both neurodegenerative and vascular processes. While excessive levels of glutamate result in neurotoxicity, in part through the over-activation of NMDARs, memantine-as a partial NMDAR antagonist, blocks the NMDA glutamate receptors to normalize the glutamatergic system and ameliorate cognitive and memory deficits. The key to memantine's therapeutic action lies in its uncompetitive binding to the NMDAR through which low affinity and rapid off-rate kinetics of memantine at the level of the NMDAR-channel preserves the physiological function of the receptor, underpinning memantine's tolerability and low adverse event profile. As the biochemical pathways evoked by NMDAR antagonism also play a role in PD and since no other drug is sufficiently effective to substitute for the first-line treatment of L-dopa despite its side effects, memantine may be useful in PD treatment with possibly fewer side effects. In spite of the relative modest nature of its adverse effects, memantine has been shown to provide only a moderate decrease in clinical deterioration in AD and VD, and hence efforts are being undertaken in the design of new and more potent memantine-based drugs to hopefully provide greater efficacy.

Cognitive Enhancers in Moderate to Severe Alzheimer's Disease

The treatment of moderate to severe Alzheimer's disease is reviewed with regard to mechanisms of action, pharmacokinetics, metabolism, safety/tolerability, and efficacy in reducing cognitive, behavioral/psychiatric, functional and global symptoms. The cholinesterase inhibitors donepezil, rivastigmine and galantamine and the N-methyl-d-aspartate receptor channel blocker memantine are moderately beneficial. Small improvements over a few months are followed by slowed mental decline. Concerning cognitive, functional and global functions, these drugs are similarly effective. Cholinesterase inhibitors also reduce apathy, memantine counteracts agitation and aggression. Serious adverse effects are rare with all four drugs. Cholinesterase inhibitors bear a risk for patients with cardiac diseases. Adverse emetic events are typical for oral formulations of these drugs, but less for rivastigmine transdermal patches. Other routes of administration and use of a galantamine prodrug are currently investigated. The superiority of combination therapies over monotherapies requires further support. Promising investigational drugs include the copper/zinc ionophore PBT2 and multifunctional hybrid molecules.

Donepezil: A Review of Pharmacological Characteristics and Role in the Management of Alzheimer Disease

Donepezil is a potent, selective, noncompetitive, and rapidly reversible inhibitor of acetylcholinesterase (AChEI) licensed for the treatment of Alzheimer disease (AD); and is the first and only AChEI licensed for the treatment of severe AD. Its efficacy as monotherapy, or in combination with the NMDA-agonist, memantine, has been documented in several randomised double-blind, placebo-controlled, short-term clinical trials, as well as long-term extension trials and observational studies. Donepezil is a well tolerated drug that is generally safe as demonstrated even in patients with multiple co-morbidities receiving polypharmacy. It has been shown that donepezil improves cognition and global function in patients with mild-to-moderate AD; and long-term efficacy is maintained for up to 50 weeks. There is a dose-response relationship, with higher doses more likely to produce symptomatic benefit. Furthermore, donepezil-treated patients may improve cognitively and show global clinical improvement in all disease stages, including severe AD. Less consistent results in all disease stages were obtained on measures of function and behavior, and observations of mood. No effect on transition to AD has been found in long-term, randomized clinical trials in mild cognitive impairment (MCI). Cost-effectiveness of the treatment has been questioned by one long-term open-label societal study of 2-years duration. This study reported modest improvement of cognition but no statistically significant benefits during donepezil treatment as compared to placebo, in terms of rates of institutionalization and progression toward greater disability. However, there is a need for further research on clinically meaningful outcomes and treatment benefits favored by patients and caregivers, which are traditionally not defined as outcomes in clinical trials. Likewise, we need to know how to select responders, what is an optimal AChE inhibition particularly during the long-term treatment, in which patients the dosage should be increased for a sustained benefit, what is the optimal duration of treatment and when is meaningful to stop the treatment. After almost two decades of donepezil use in everyday clinical practice these issues are still unresolved.

Critical appraisal of the long-term impact of memantine in treatment of moderate to severe Alzheimer's disease

Alzheimer's disease is the most common cause of dementia in older adults. The clinical features include progressive memory decline as well as cognitive deficits with executive dysfunction, language, visual perceptual difficulties, apraxia and agnosia. During the moderate to severe stage of the disease, there is a major decline in memory and function, while neuropsychiatric disturbances often emerge and patients become difficult to manage. These distressing symptoms increase caregiver burden and add to the direct costs of care of the patients. Any improvements in patient function and behavioral symptoms can reduce caregiver burden. Memantine has been available for a number of years in Europe and in North America. In this article, we examine the pharmacological rationale for its use, and the current clinical evidence for its efficacy and long-term effectiveness in the management of cognitive and behavioral symptoms in moderate to severe stages of Alzheimer's disease.

Memantine: a review of studies into its safety and efficacy in treating Alzheimer's disease and other dementias

Memantine is an uncompetitive N-methyl-D-aspartate receptor antagonist with moderate affinity. Its mechanism of action is neuroprotective and potentially therapeutic in several neuropsychiatric diseases. It has been approved by the FDA for the treatment of moderate to severe Alzheimer's disease (AD) either as a monotherapy or in combination with cholinesterase inhibitors. This review covers key studies of memantine's safety and efficacy in treating moderate to severe AD. It also covers current research into other dementias including but not exclusively mild AD and vascular dementia. Other studies on the efficacy of memantine for other neuropsychiatric diseases are discussed. Memantine is a safe and effective drug that merits further research on several topics. Clinicians should be aware of new studies and potential uses of memantine because of its safety and efficacy.

Memantine: a review of its use in moderate to severe Alzheimer's disease

Memantine is an uncompetitive, moderate-affinity NMDA receptor antagonist that is indicated for the treatment of moderate to severe Alzheimer's disease. In well designed trials in patients with moderate to severe Alzheimer's disease, oral memantine monotherapy improved outcomes in the area of functional ability more than placebo in one trial, but in a second trial, treatment differences did not reach significance. Memantine has a distinct mode of action compared with that of acetylcholinesterase (AChE) inhibitors, and in a well designed study, combination therapy with memantine plus donepezil improved outcomes more than donepezil plus placebo in all four domains (function, cognition, behaviour and global change). Memantine is generally well tolerated, with adverse events occurring with a similar incidence to that reported with placebo. In modelled cost-effectiveness analyses, memantine was dominant to no therapy in regard to cost per quality-adjusted life-year (QALY) gained, and the combination of memantine plus donepezil was dominant to donepezil therapy alone in regard to QALYs gained when treatment periods exceeded 1 year in patients with moderate to severe disease. Thus, in the management of patients with moderate to severe Alzheimer's disease, memantine provides an effective treatment option. To date, clinical trial support is greater for memantine use in combination with an AChE inhibitor, while more data are needed to confirm its efficacy as monotherapy.

Update on the use of memantine in Alzheimer's disease

Memantine is a low to moderate affinity N-methyl-D-aspartate receptor (NMDAR) antagonist. The effects of memantine in Alzheimer's disease (AD) have been studied in 7 randomized controlled trials in many post-hoc analyses. Three out of four RCTs in patients with moderate to severe AD (Mini Mental State Examination [MMSE] <14) showed a statistically significant but clinically small positive effect of memantine on cognition, global functioning, activities of daily living (ADL) and neuropsychiatric symptoms. No effects on these outcome measures could be found in the three RCTs studying patients with mild to moderate AD (MMSE 14-24). Two of these studies evaluated the effect of addition of memantine to donepezil. Only the study in patients with mild to moderate AD showed a positive effect of addition of memantine on cognition, ADL, global functioning and neuropsychiatric functioning. Cost-effectiveness of memantine therapy remains controversial. Post-hoc analyses and observational studies suggest some effects on agitation/aggression, delusions or hallucinations. Side effects of memantine are usually mild and seem to be comparable with placebo. In this review, an oversight of pharmacodynamics and pharmacokinetics of memantine is presented. Also, published data concerning efficacy and safety in patients with AD are presented.

Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system--too little activation is bad, too much is even worse

The neurotransmitter glutamate activates several classes of metabotropic receptor and three major types of ionotropic receptor--alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA). The involvement of glutamate mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD) is finding increasing scientific acceptance. Central to this hypothesis is the assumption that glutamate receptors, in particular of the NMDA type, are overactivated in a tonic rather than a phasic manner. Such continuous, mild, chronic activation ultimately leads to neuronal damage/death. Additionally, impairment of synaptic plasticity (learning) may result not only from neuronal damage per se but may also be a direct consequence of this continuous, non-contingent NMDA receptor activation. Complete NMDA receptor blockade has also been shown to impair neuronal plasticity, thus, both hypo- and hyperactivity of the glutamatergic system leads to dysfunction. Memantine received marketing authorization from the EMEA (European Medicines Agency) for the treatment of moderate to severe AD in Europe and was subsequently also approved by the FDA (Food and Drug Administration) for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive NMDA receptor antagonist with strong voltage-dependency and fast kinetics. This review summarizes existing hypotheses on the mechanism of action (MOA) of memantine in an attempt to understand how the accepted interaction with NMDA receptors could allow memantine to provide both neuroprotection and reverse deficits in learning/memory by the same MOA.

The uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist memantine prolongs spatial memory in a rat delayed radial-arm maze memory task

In the present study, we evaluated the effects of memantine in a delayed radial-arm maze rat task, consisting of an acquisition phase followed 18 h later by a win-shift retrieval test. When administered 20 min before acquisition, memantine elicited an inverted U-shape dose-response relationship, with low doses (0.3 and 0.56 mg/kg) reducing the number of errors committed during the retrieval test, while high doses (3 and 10 mg/kg) disrupted maze running. Memantine given immediately after acquisition or 20 min before retrieval failed to affect performance. Co-administration of subthreshold doses of memantine with either the CB(1) receptor antagonist rimonabant or the acetylcholine esterase inhibitor donepezil failed to enhance performance. Thus, low doses of memantine enhance acquisition processes that lead to prolonged spatial memory.

Memantine Treatment of Cognitive Symptoms in Mild to Moderate Alzheimer Disease: Secondary Analyses From a Placebo-controlled Randomized Trial

Memantine, an N-methyl-D-aspartate receptor antagonist, is approved in the United States and Europe for the treatment of moderate to severe Alzheimer disease (AD) and has also been investigated in patients with mild to moderate AD. To characterize the specific cognitive benefits of memantine in patients with mild to moderate AD, a post hoc analysis was conducted of a 24-week randomized, double-blind, placebo-controlled, clinical trial comparing memantine (10 mg twice daily) to placebo. Cognition was assessed using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) total score, individual items, and aggregated subscales, using a mixed model repeated measures analysis. As assessed by the ADAS-cog total score, participants in the placebo group demonstrated significantly more cognitive decline from baseline than participants treated with memantine at all visits beginning at week 8. Subjects treated with placebo also declined significantly more than individuals in the memantine group on 5 of 11 ADAS-cog individual items: orientation, language, comprehension, word finding, and recall of test instructions. Out of 3 ADAS-cog aggregated item subscales (language, memory, and praxis), outcomes in 2 (language and memory) favored memantine. Consistent with findings from trials conducted in moderate to severe AD patients, this post hoc analysis of a randomized clinical trial suggests that memantine benefits core aspects of language and some aspects of memory in patients with mild to moderate AD.