Systematic review and meta-analysis of combination therapy with cholinesterase inhibitors and memantine in Alzheimer's disease and other dementias

Memantine: Updating a rare success story in pro-cognitive therapeutics

The great potential for NMDA receptor modulators as druggable targets in neurodegenerative disorders has been met with limited success. Considered one of the rare exceptions, memantine has consistently demonstrated restorative and prophylactic properties in many AD models. In clinical trials memantine slows the decline in cognitive performance associated with AD. Here, we provide an overview of the basic properties including pharmacological targets, toxicology and cellular effects of memantine. Evidence demonstrating reductions in molecular, physiological and behavioural indices of AD-like impairments associated with memantine treatment are also discussed. This represents both an extension and homage to Dr. Chris Parson's considerable contributions to our fundamental understanding of a success story in the AD treatment landscape.

Effects of Virtual Reality-Based Cognitive Training in the Elderly with and without Mild Cognitive Impairment

OBJECTIVE

This study aimed to introduce a 4-week long fully immersive virtual reality-based cognitive training (VRCT) program that could be applied for both a cognitively normal elderly population and patients with mild cognitive impairment (MCI). In addition, we attempted to investigate the neuropsychological effects of the VRCT program in each group.

METHODS

A total of 56 participants, 31 in the MCI group and 25 in the cognitively normal elderly group, underwent eight sessions of VRCT for 4 weeks. In order to evaluate the effects of the VRCT, the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet was administered before and after the program. The program' s safety was assessed using a simulator sickness questionnaire (SSQ), and availability was assessed using the presence questionnaire.

RESULTS

After the eighth session of the VRCT program, cognitive improvement was observed in the ability to learn new information, visuospatial constructional ability, and frontal lobe function in both groups. At the baseline evaluation, based on the SSQ, the MCI group complained of disorientation and nausea significantly more than the cognitively normal elderly group did. However, both groups showed a reduction in discomfort as the VRCT program progressed.

CONCLUSION

We conclude that our VRCT program helps improve cognition in both the MCI group and cognitively normal elderly group. Therefore, the VRCT is expected to help improve cognitive function in elderly populations with and without MCI.

Preventive Effects of Continuous Betaine Intake on Cognitive Impairment and Aberrant Gene Expression in Hippocampus of 3xTg Mouse Model of Alzheimer's Disease

BACKGROUND

The deposition of amyloid-β (Aβ) and hyperphosphorylation of tau are well-known as the pathophysiological features of Alzheimer's disease (AD), leading to oxidative stress and synaptic deficits followed by cognitive symptoms. We already demonstrated that betaine (glycine betaine) prevented cognitive impairment and hippocampal oxidative stress in mice intracerebroventricularly injected with an active fragment of Aβ, whereas the effect of betaine in chronic models of AD remains unknown.

OBJECTIVE

Our objective was to investigate the effects of chronic betaine intake on cognitive impairment and aberrant expression of genes involved in synapse and antioxidant activity in the hippocampus of a genetic AD model.

METHODS

We performed cognitive tests and RT-PCR in the hippocampus in 3xTg mice, a genetic AD model.

RESULTS

Cognitive impairment in the Y-maze and novel object recognition tests became evident in 3xTg mice at 9 months old, and not earlier, indicating that cognitive impairment in 3xTg mice developed age-dependently. To examine the preventive effect of betaine on such cognitive impairment, 3xTg mice were fed betaine-containing water for 3 months from 6 to 9 months old, and subsequently subjected to behavioral tests, in which betaine intake prevented the development of cognitive impairment in 3xTg mice. Additionally, the expression levels of genes involved in synapse and antioxidant activity were downregulated in hippocampus of 3xTg mice at 9 months old compared with age-matched wild-type mice, which were suppressed by betaine intake.

CONCLUSION

Betaine may be applicable as an agent preventing the progression of AD by improving the synaptic structure/function and/or antioxidant activity.

Multi-Target Drug Candidates for Multifactorial Alzheimer's Disease: AChE and NMDAR as Molecular Targets

Alzheimer's disease (AD) is one of the most common forms of dementia among elder people, which is a progressive neurodegenerative disease that results from a chronic loss of cognitive activities. It has been observed that AD is multifactorial, hence diverse pharmacological targets that could be followed for the treatment of AD. The Food and Drug Administration has approved two types of medications for AD treatment such as cholinesterase inhibitors (ChEIs) and N-methyl-D-aspartic acid receptor (NMDAR) antagonists. Rivastigmine, donepezil, and galantamine are the ChEIs that have been approved to treat AD. On the other hand, memantine is the only non-competitive NMDAR antagonist approved in AD treatment. As compared with placebo, it has been revealed through clinical studies that many single-target therapies are unsuccessful to treat multifactorial Alzheimer's symptoms or disease progression. Therefore, due to the complex nature of AD pathophysiology, diverse pharmacological targets can be hunted. In this article, based on the entwined link of acetylcholinesterase (AChE) and NMDAR, we represent several multifunctional compounds in the rational design of new potential AD medications. This review focus on the significance of privileged scaffolds in the generation of the multi-target lead compound for treating AD, investigating the idea and challenges of multi-target drug design. Furthermore, the most auspicious elementary units for designing as well as synthesizing hybrid drugs are demonstrated as pharmacological probes in the rational design of new potential AD therapeutics.

Alzheimer's Disease Therapeutic Approaches

Alzheimer's disease (AD) was first described and diagnosed by Dr. Alois Alzheimer in 1906 (Hippius and Neundorfer, Dialogues Clin Neurosc 5:101-108, 2003). According to World Health Organization (WHO), AD is the most common cause of dementia, accounting for as many as 60-70% of senile dementia cases and affecting 47.5 million people worldwide (data from 2015) (Dementia Fact Sheet No 362. http://who.int/mediacentre/factsheets/fs362/en/ ). The median survival time after the onset of dementia ranges from 3.3 to 11.7 years (Todd et al. Int J Geriatr Psychiatry 28:1109-1124, 2013). AD is characterized as a severe, chronic, incurable, and progressive neurodegenerative disorder, associated with memory loss and cognition impairment accompanied by abnormal behavior and personality changes (Godyn et al. Pharmacol Rep 68:127-138, 2016). AD is characterized by neuronal death, which usually correlates with the appearance of key neuropathological changes, including acetylcholine deficiency, glutamate excitotoxicity, extracellular deposition of β-amyloid (Aβ plaques), intracellular neurofibrillary tangles by hyperphosphorylated tau protein deposits, neuroinflammation, and widespread neuronal loss (Godyn et al. Pharmacol Rep 68:127-138, 2016; Graham et al. Annu Rev. Med 68:413-430, 2017). The discovery of the degeneration of cholinergic neurons and the reduction of acetylcholine levels in postmortem studies of patients resulted in the use of drugs that leads to the increase of acetylcholine levels in brain (Dubois et al. Lacet Neurol 13:614-629, 2014). At present there is no preventative or curative treatment that interferes with the development of the disease. However, in recent years progress was made in the development of cholinergic drugs which have a positive effect on disease progression. Nowadays, specific drugs that can inhibit the enzyme that degrades acetylcholine are used. The development of new effective drugs involves a difficult and time-consuming process, accompanied by a very high failure rate. In the absence of effective therapies, the estimated number of people with dementia will reach 115 to 131, five million by 2050 (Dubois et al. Lacet Neurol 13:614-629, 2014; Cummings et al. Alzheimers Res Ther 6:37, 2014). Novel therapies and new targets required for developing more effective drugs for the treatment of AD patients are urgently needed.

Aging and Neuroinflammatory Disorders: New Biomarkers and Therapeutic Targets

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Chronic neuroinflammation is a common feature of the pathogenic mechanisms involved in various neurodegenerative age-associated disorders, such as Alzheimer's disease, multiple sclerosis, Parkinson’s disease, and dementia.

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In particular, persistent low-grade inflammation may disrupt the brain endothelial barrier and cause a significant increase of pro-inflammatory cytokines and immune cells into the cerebral tissue that, in turn, leads to microglia dysfunction and loss of neuroprotective properties.

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Nowadays, growing evidence highlights a strong association between persistent peripheral inflammation, as well as metabolic alterations, and neurodegenerative disorder susceptibility. The identification of common pathways involved in the development of these diseases, which modulate the signalling and immune response, is an important goal of ongoing research.

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The aim of this review is to elucidate which inflammation-related molecules are robustly associated with the risk of neurodegenerative diseases. Of note, peripheral biomarkers may represent direct measures of pathophysiologic processes common of aging and neuroinflammatory processes. In addition, molecular changes associated with the neurodegenerative process might be present many decades before the disease onset. Therefore, the identification of a comprehensive markers panel, closely related to neuroinflammation, could be helpful for the early diagnosis, and the identification of therapeutic targets to counteract the underlying chronic inflammatory processes.

Effect of Paper-Based Cognitive Training in Early Stage of Alzheimer's Dementia

Background and Purpose

Cognitive training refers to a series of standardized tasks with inherent challenges that target specific cognitive domains. Positive outcome of cognitive training in persons with Alzheimer's disease has been reported. In this study, the objective was to design sets of cognitive training program, “Gipum-seo” which is combined cognitive training, consists of different levels of difficulty using predesigned paper-and-pencil exercises. Also, to evaluate the effects of the cognitive training on patients' with early stage of Alzheimer's disease.

Methods

The subjects for this study were forty participants who were diagnosed with early stage of Alzheimer's dementia. To test the efficacy of paper-based cognitive training programs to cognition, all patients were randomly grouped to either an intervention group (n=20) or a control group (n=20). The intervention group regularly received 24 sessions of paper-based cognitive training over a 12-week period. Neuropsychological examinations were conducted before and after this training period.

Results

After the 12 weeks, the intervention group showed a significant change in Korean version of the Mini-Mental State Examination (25.90±3.8), compared to the control group (23.7±2.8) (p=0.042). The training group also showed a significant improvement in language, attention and executive function, as compared with controls.

Conclusions

Paper-based cognitive training might have beneficial effects on the general cognitive functions in the early stage of Alzheimer's dementia.

Pioglitazone Improves Mitochondrial Organization and Bioenergetics in Down Syndrome Cells

Mitochondrial dysfunction plays a primary role in neurodevelopmental anomalies and neurodegeneration of Down syndrome (DS) subjects. For this reason, targeting mitochondrial key genes, such as PGC-1α/PPARGC1A, is emerging as a good therapeutic approach to attenuate cognitive disability in DS. After demonstrating the efficacy of the biguanide metformin (a PGC-1α activator) in a cell model of DS, we extended the study to other molecules that regulate the PGC-1α pathway acting on PPAR genes. We, therefore, treated trisomic fetal fibroblasts with different doses of pioglitazone (PGZ) and evaluated the effects on mitochondrial dynamics and function. Treatment with PGZ significantly increased mRNA and protein levels of PGC-1α. Mitochondrial network was fully restored by PGZ administration affecting the fission-fusion mitochondrial machinery. Specifically, optic atrophy 1 (OPA1) and mitofusin 1 (MFN1) were upregulated while dynamin-related protein 1 (DRP1) was downregulated. These effects, together with a significant increase of basal ATP content and oxygen consumption rate, and a significant decrease of reactive oxygen species (ROS) production, provide strong evidence of an overall improvement of mitochondria bioenergetics in trisomic cells. In conclusion, we demonstrate that PGZ is able to improve mitochondrial phenotype even at low concentrations (0.5 μM). We also speculate that a combination of drugs that target mitochondrial function might be advantageous, offering potentially higher efficacy and lower individual drug dosage.

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.

Predictors of discontinuation, efficacy, and safety of memantine treatment for Alzheimer's disease: meta-analysis and meta-regression of 18 randomized clinical trials involving 5004 patients

BACKGROUND

The risk-benefit relationship of memantine treatment for Alzheimer's disease (AD) remains unclear. In addition, variability between the results of clinical trials has been observed. The aim of this study was to investigate the risk-benefit relationship of memantine treatment in patients with AD and to determine the predictor effect of patient, intervention, and study design related covariates.

METHODS

A systematic review and meta-analysis of double-blind, placebo controlled clinical trials was performed. Primary outcomes were all-cause discontinuation, discontinuation due to adverse events (AE) and efficacy on cognitive function. Odds ratio (OR) and standard mean difference (SMD) with 95% confidence intervals were calculated. Meta-regression was conducted to identify related covariates. Cochrane Collaboration tool was used to evaluate the risk of bias of included trials.

RESULTS

Eighteen studies involving 5004 patients were included. No differences between memantine and placebo were found for all-cause treatment discontinuation (OR=0.97 [0.82, 1.14]) and discontinuation due to AE (OR=1.18 [0.91, 1.53]). Memantine showed small improvement on cognitive function (SMD=0.15 [0.08, 0.22]). Baseline functional ability was positively associated with all-cause treatment discontinuation and discontinuation due to AE.

CONCLUSIONS

Our study suggests that memantine has a very small efficacy on AD symptomatology and its safety profile is similar to that of placebo. No evidence of treatment discontinuation improvement with memantine is found, indicating a dubious risk-benefit relationship. No intervention characteristic or subgroup of patients clearly shows a significantly better risk-benefit relationship.

PROSPERO REGISTRATION

CRD42014015696 .

Behavioural effects of novel multitarget anticholinesterasic derivatives in Alzheimer's disease

The current pharmacological approach to Alzheimer's disease (AD) treatment, mostly based on acetylcholinesterase inhibitors (AChEIs), is being revisited, especially in terms of the temporal frames and the potential benefits of their noncanonic actions, raising the question of whether inhibitors of AChE might also act in a disease-modifying manner. Besides, in the last decades, the pharmacophoric moieties of known AChEIs have been covalently linked to other pharmacophores in the pursuit of multitarget hybrid molecules that are expected to induce long-lasting amelioration of impaired neurotransmission and clinical symptoms but also to exert disease-modifying effects. Our research consortium has synthesized and defined the pharmacological profile of new AChEIs derivatives of potential interest for the treatment of AD. Among these, huprines and derivatives have been characterized successfully. Huprine X, a reversible AChE inhibitor, designed by molecular hybridization of tacrine and huperzine A, has been shown to affect the amyloidogenic process in vitro, and the AD-related neuropathology in vivo in mice models of the disease. More recently, we have shown that a group of donepezil-huprine heterodimers exerts a highly potent and selective inhibitory action on AChE both in vitro and ex vivo, simultaneously interacting with both peripheral and catalytic binding sites, and inhibiting the β-amyloid aggregation, whereas some levetiracetam-huprine hybrids have been shown to reduce epileptiform activity, neuroinflammation and amyloid burden in an animal model of AD. Here, we summarize the behavioural correlates of these noncanonic actions as assessed in three distinct biological scenarios: middle-age, cognitive deficits associated with ageing and AD-like phenotype in mice. Besides the improvement in the hallmark cognitive symptomatology without inducing side effects, these drugs have shown to be able to modulate emotional and anxiety-like behaviours or to reduce spontaneous seizures, all of them related to the so-called 'behavioural and psychological symptoms of dementia'. Overall, the studies show that these novel multitarget anticholinesterasics exert noncanonic actions providing symptomatic and disease-modifying benefits of potential interest for the management of AD.

Pharmacotherapy for Dementia: A Practical Approach to the Use of Cholinesterase Inhibitors and Memantine

Cholinesterase inhibitors and memantine are the only classes of drugs approved for the treatment of dementia due to Alzheimer's disease. This article provides evidence-based recommendations to address the issues regarding the use of cholinesterase inhibitors and memantine in clinical practice. It includes their efficacy, timing, assessment, use in institutionalized patients, combined use, and use in other dementia types. However, most of the studies are of short duration (<1 year) and are mainly focused on cognitive and global improvement, whereas the practical issue of their use in daily practice such as optimal duration of treatment, long-term efficacy and delaying institutionalization are limited.

Improvement of Cognitive Function after Computer-Based Cognitive Training in Early Stage of Alzheimer's Dementia

Background and Purpose

Cognitive training is known to be an effective tool in enhancing cognitive functioning. Research has also shown that playing video game improves certain aspects of visual attention and cognitive processing speed. The effect of computer-based cognitive training has not been demonstrated so far. This study therefore evaluated whether computer-based cognitive training improved the cognitive abilities in patients with early stage of Alzheimer's dementia.

Methods

Totally, 20 participants (early stage of Alzheimer's dementia) participated in this study. To test the effectiveness of computer-based cognitive training programs to cognition, all patients were randomly allocated to either an intervention group (n=10) or a control group (n=10). The intervention group regularly received 24 sessions of computer-based cognitive training, over a 12 week period. Neuropsychological examinations were conducted before and after this training period.

Results

After 12 weeks, the intervention group showed a significant change in language of Korean version of the Mini-Mental State Examination (K-MMSE), compared with the baseline cognitive examinations. Also, there was greater improvement in language, attention, calculation, verbal memory, and frontal function for the experimental group, as compared with controls.

Conclusions

Computer-based cognitive training might have beneficial effects on the general cognitive functions in early stage of Alzheimer's dementia.

Combination Therapy Showed Limited Superiority Over Monotherapy for Alzheimer Disease: A Meta-analysis of 14 Randomized Trials

BACKGROUND

Acetylcholinesterase inhibitor (AChEI) and memantine are recognized drug treatments with limited clinical efficacy. Combination therapy for patients with Alzheimer disease (AD) was suggested, but the additional benefit of combination therapy is still controversial.

AIM

To evaluate the additional benefit of combination therapy over monotherapy with either AChEI or memantine.

METHODS

Prospective randomized controlled trials were searched from the OVID databases. The trials were eligible if study subjects were diagnosed with AD, and were randomized to compare combination therapy with monotherapy. Any clinical assessment measured using validated scales on cognitive function, activities of daily living, behavioral problems, and global changes were the primary outcomes, and any reported adverse events were the secondary outcomes. Quality of studies and risk of bias were evaluated.

RESULTS

Fourteen randomized trials were identified between 2004 and 2015 from the United States, Canada, Germany, Japan, China, and Korea. A total of 5019 patients with AD were randomly assigned to receive combination therapy of AChEI and memantine or monotherapy with AChEI or memantine. Combination therapy showed no significant benefit on cognitive function (mean difference [MD] of MMSE = 0.06, 95% CI -0.52 to 0.65), activities of daily living (MD of ADCS-ADL = -0.15, 95% CI -1.08 to 0.78), neuropsychiatric symptoms and behavioral problems (MD of NPI = -1.85, 95% CI -4.83 to 1.13), and global changes (MD of CIBIC-plus = 0.01, 95% CI -0.25 to 0.28). In subgroup analyses, combination therapy can improve cognitive function more than memantine alone; and it can significantly relieve neuropsychiatric symptoms and behavioral problems when concomitantly used with donepezil. No additional adverse event was reported in the combination therapy.

CONCLUSION

Combination therapy only showed the benefit on neuropsychiatric symptoms and behavioral problems in moderate-to-severe AD, but no other superiority in terms of cognitive function, activities of daily living, and global changes. Although reported adverse events were comparable, the additional cost for combination therapy may be unnecessary.

Combination therapy with cholinesterase inhibitors and memantine for Alzheimer's disease: a systematic review and meta-analysis

BACKGROUND

We performed an updated meta-analysis of randomized controlled trials of combination therapy with cholinesterase inhibitors and memantine in patients with Alzheimer's disease.

METHODS

We reviewed cognitive function, activities of daily living, behavioral disturbance, global assessment, discontinuation rate, and individual side effects.

RESULTS

Seven studies (total n=2182) were identified. Combination therapy significantly affected behavioral disturbance scores (standardized mean difference=-0.13), activity of daily living scores (standardized mean difference=-0.10), and global assessment scores (standardized mean difference=-0.15). In addition, cognitive function scores (standardized mean difference=-0.13, P=.06) exhibited favorable trends with combination therapy. The effects of combination therapy were more significant in the moderate-to-severe Alzheimer's disease subgroup in terms of all efficacy outcome scores. The discontinuation rate was similar in both groups, and there were no significant differences in individual side effects.

CONCLUSIONS

Combination therapy was beneficial for the treatment of moderate-to-severe Alzheimer's disease in terms of cognition, behavioral disturbances, activities of daily living, and global assessment was well tolerated.

AVCRI104P3, a novel multitarget compound with cognition-enhancing and anxiolytic activities: studies in cognitively poor middle-aged mice

The present work describes, for the first time, the in vivo effects of the multitarget compound AVCRI104P3, a new anticholinesterasic drug with potent inhibitory effects on human AChE, human BuChE and BACE-1 activities as well as on the AChE-induced and self-induced Aβ aggregation. We characterized the behavioral effects of chronic treatment with AVCRI104P3 (0.6 μmol kg(-1), i.p., 21 days) in a sample of middle aged (12-month-old) male 129/Sv×C57BL/6 mice with poor cognitive performance, as shown by the slow acquisition curves of saline-treated animals. Besides, a comparative assessment of cognitive and non-cognitive actions was done using its in vitro equipotent doses of huprine X (0.12 μmol kg(-1)), a huperzine A-tacrine hybrid. The screening assessed locomotor activity, anxiety-like behaviors, cognitive function and side effects. The results on the 'acquisition' of spatial learning and memory show that AVCRI104P3 exerted pro-cognitive effects improving both short- and long-term processes, resulting in a fast and efficient acquisition of the place task in the Morris water maze. On the other hand, a removal test and a perceptual visual learning task indicated that both AChEIs improved short-term 'memory' as compared to saline treated mice. Both drugs elicited the same response in the corner test, but only AVCRI104P3 exhibited anxiolytic-like actions in the dark/light box test. These cognitive-enhancement and anxiolytic-like effects demostrated herein using a sample of middle-aged animals and the lack of adverse effects, strongly encourage further studies on AVCRI104P3 as a promising multitarget therapeutic agent for the treatment of cholinergic dysfunction underlying natural aging and/or dementias.

Anti-dementia drugs and co-medication among patients with Alzheimer's disease : investigating real-world drug use in clinical practice using the Swedish Dementia Quality Registry (SveDem)

BACKGROUND

There is a substantial risk of drug-interactions, adverse events, and inappropriate drug use (IDU) among frail Alzheimer's disease (AD) patients; however, there are few studies about co-medication and IDU in clinical settings.

OBJECTIVES

To investigate anti-dementia drugs, associated characteristics of cholinesterase inhibitors (ChEIs) and NMDA antagonists, co-medication, and IDU in a large population of outpatients with mild AD.

METHODS

In this cross-sectional analysis of medication characteristics, we analyzed data from the Swedish Dementia Quality Registry (SveDem) on 5,907 newly diagnosed AD patients who were registered in memory clinics. SveDem is a national quality registry in Sweden, which was established in 2007 to evaluate and improve dementia healthcare. Comparisons were performed concerning co-medications, use of ≥3 psychotropic drugs (IDU) and polypharmacy (≥5 drugs) based on anti-dementia treatment (ChEIs or NMDA antagonists). Information on baseline characteristics such as age, sex, living conditions, cognitive evaluation based on the Mini-Mental State Examination (MMSE) score, and diagnostic work-up was also evaluated.

RESULTS

The majority of the AD patients were in the mild stage of the disease. Overall, 4,342 (75.4 %) patients received any ChEI, 438 (7.6 %) used an NMDA antagonist and 74 (1.3 %) patients were treated with both. However, 907 (15.7 %) patients were not treated with any anti-dementia drug. While polypharmacy was seen in 33.5 % of patients, only 2.6 % concurrently used ≥3 psychotropic medications. Patients on ChEIs were significantly younger, had a higher MMSE score and were treated with a smaller number of medications (a proxy for overall co-morbidity). Co-medication with antipsychotics [3.3 vs. 7.6 %; adjusted odds ratio (OR) 0.55 (95 % CI 0.38-0.79)] and anxiolytics [5.8 vs. 10.9 %; adjusted OR 0.62 (95 % CI 0.46-0.84)] was significantly lower in the ChEI+ group than in those with no anti-dementia treatment.

CONCLUSION

Patients taking ChEIs were treated with less antipsychotics and anxiolytics than those not taking ChEIs. More research is warranted to elucidate whether use of ChEIs in clinical practice can reduce the need for psychotropic drugs in AD patients.

Prescribing drugs for Alzheimer's disease in primary care: managing cognitive symptoms

There are currently no interventions that cure or even alter the progressive course of dementia. In the UK, donepezil, galantamine and rivastigmine are licensed for symptomatic treatment of mild to moderate Alzheimer's disease, and memantine is licensed for use in moderate to severe Alzheimer's disease.1-4 These drugs improve cognitive function by a modest amount compared with placebo.5 Although the National Institute for Health and Care Excellence (NICE) stipulates that such treatment should be initiated by a specialist, in many parts of the UK responsibility for continued prescription of these drugs is being transferred to primary care. Here we review the evidence for drugs prescribed for cognitive symptoms in Alzheimer's disease and highlight key issues for those who are prescribing them.

Combotherapy and current concepts as well as future strategies for the treatment of Alzheimer's disease

It has been estimated that 35.6 million people globally had dementia in 2010 and the prevalence of dementia has been predicted to double every 20 years. Thus, 115.4 million people may be living with dementia in 2050. Alzheimer's disease (AD) is the leading cause of dementia and is present in 60%-70% of people with dementia. Unfortunately, there are few approved drugs that can alleviate the cognitive or behavioral symptoms of AD dementia. Recent studies have revealed that pathophysiological changes related to AD occur decades before the appearance of clinical symptoms of dementia. This extended preclinical phase of AD provides a critical chance for disease-modifying agents to halt or delay the relentless process of AD. Although several trials targeting various pathological processes are ongoing, the examination of the combined use of different approaches to combat AD seems warranted. In this article, we will review current therapies, future strategies, and ongoing clinical trials for the treatment of AD with a special focus on combination therapies. Furthermore, preventive strategies for cognitively normal subjects in the presymptomatic stages of AD will also be addressed. In this review, we discuss current hypotheses of the disease process. In the decades since the approval of cholinesterase inhibitors, no new drug has ultimately demonstrated clear success in clinical trials. Given the difficulties that have been encountered in attempts to identify a single drug that can treat AD, we must pursue effective multi-target strategies, ie, combination therapies. The combination of cholinesterase inhibitors and memantine is considered well tolerated and safe, and this combination benefits patients with moderate-to-severe AD. In contrast, with the exception of adjuvant therapies of conventional drugs, combinations of different disease-modifying agents with different mechanisms may have promising synergic effects and benefit cognition, behavior, and daily living function.

Therapeutics of Alzheimer's disease: Past, present and future

Alzheimer's disease (AD) is the most common cause of dementia worldwide. The etiology is multifactorial, and pathophysiology of the disease is complex. Data indicate an exponential rise in the number of cases of AD, emphasizing the need for developing an effective treatment. AD also imposes tremendous emotional and financial burden to the patient's family and community. The disease has been studied over a century, but acetylcholinesterase inhibitors and memantine are the only drugs currently approved for its management. These drugs provide symptomatic improvement alone but do less to modify the disease process. The extensive insight into the molecular and cellular pathomechanism in AD over the past few decades has provided us significant progress in the understanding of the disease. A number of novel strategies that seek to modify the disease process have been developed. The major developments in this direction are the amyloid and tau based therapeutics, which could hold the key to treatment of AD in the near future. Several putative drugs have been thoroughly investigated in preclinical studies, but many of them have failed to produce results in the clinical scenario; therefore it is only prudent that lessons be learnt from the past mistakes. The current rationales and targets evaluated for therapeutic benefit in AD are reviewed in this article. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.