Memantine therapy of behavioral symptoms in community-dwelling patients with moderate to severe Alzheimer's disease

In silico molecular modeling and in vitro biological screening of novel benzimidazole-based piperazine derivatives as potential acetylcholinesterase and butyrylcholinesterase inhibitors

New series of benzimidazole incorporating piperazine moieties in single molecular framework has been reported. The structures of the synthesized derivatives were assigned by 1H-NMR, 13C-NMR, and HR-MS techniques. The hybrid derivatives were evaluated for their acetylcholinesterase and butyrylcholinesterase inhibition effect. All the synthesized analogs showed good to moderate inhibitory effect ranging from IC50 value 0.20 ± 0.01 µM to 0.50 ± 0.10 µM for acetylcholinesterase and from IC50 value 0.25 ± 0.01 µM to 0.70 ± 0.10 µM for butyrylcholinesterase except one that showed least potency with IC50 value 1.05 ± 0.1 µM and 1.20 ± 0.1 µM. The differences in inhibitory potential of synthesized compounds were due to the nature and position of substitution attached to the main ring. Additionally, molecular docking study was carried out for most active in order to explore the binding interactions established by ligand (active compounds) with the active residues of targeted AChE & BuChE enzyme.

Cholinergic Antagonists and Behavioral Disturbances in Neurodegenerative Diseases

Cholinergic antagonists interfere with synaptic transmission in the central nervous system and are involved in pathological processes in patients with neurocognitive disorders (NCD), such as behavioral and psychological symptoms of dementia (BPSD). In this commentary, we will briefly review the current knowledge on the impact of cholinergic burden on BPSD in persons with NCD, including the main pathophysiological mechanisms. Given the lack of clear consensus regarding symptomatic management of BPSD, special attention must be paid to this preventable, iatrogenic condition in patients with NCD, and de-prescription of cholinergic antagonists should be considered in patients with BPSD.

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.

Molecular Mechanism of Autophagy: Its Role in the Therapy of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder of progressive dementia that is characterized by the accumulation of beta-amyloid (Aβ)-containing neuritic plaques and intracellular Tau protein tangles. This distinctive pathology indicates that the protein quality control is compromised in AD. Autophagy functions as a "neuronal housekeeper" that eliminates aberrant protein aggregates by wrapping then into autophagosomes and delivering them to lysosomes for degradation. Several studies have suggested that autophagy deficits in autophagy participate in the accumulation and propagation of misfolded proteins (including Aβ and Tau). In this review, we summarize current knowledge of autophagy in the pathogenesis of AD, as well as some pathways targeting the restoration of autophagy. Moreover, we discuss how these aspects can contribute to the development of disease-modifying therapies in AD.

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.

Sequential drug treatment algorithm for agitation and aggression in Alzheimer's and mixed dementia

INTRODUCTION

Behavioural and psychological symptoms of dementia (BPSD) include agitation and aggression in people with dementia. BPSD is common on inpatient psychogeriatric units and may prevent individuals from living at home or in residential/nursing home settings. Several drugs and non-pharmacological treatments have been shown to be effective in reducing behavioural and psychological symptoms of dementia. Algorithmic treatment may address the challenge of synthesizing this evidence-based knowledge.

METHODS

A multidisciplinary team created evidence-based algorithms for the treatment of behavioural and psychological symptoms of dementia. We present drug treatment algorithms for agitation and aggression associated with Alzheimer's and mixed Alzheimer's/vascular dementia. Drugs were appraised by psychiatrists based on strength of evidence of efficacy, time to onset of clinical effect, tolerability, ease of use, and efficacy for indications other than behavioural and psychological symptoms of dementia.

RESULTS

After baseline assessment and discontinuation of potentially exacerbating medications, sequential trials are recommended with risperidone, aripiprazole or quetiapine, carbamazepine, citalopram, gabapentin, and prazosin. Titration schedules are proposed, with adjustments for frailty. Additional guidance is given on use of electroconvulsive therapy, optimization of existing cholinesterase inhibitors/memantine, and use of pro re nata medications.

CONCLUSION

This algorithm-based approach for drug treatment of agitation/aggression in Alzheimer's/mixed dementia has been implemented in several Canadian Hospital Inpatient Units. Impact should be assessed in future research.

Design, Synthesis, and Biological Evaluation of a New Series of Biphenyl/Bibenzyl Derivatives Functioning as Dual Inhibitors of Acetylcholinesterase and Butyrylcholinesterase

Alzheimer’s disease (AD), the most common form of dementia in adults, is a progressive neurodegenerative disorder of the brain characterized by loss of memory and steady deterioration of cognition. Here, a series of symmetrical molecules containing biphenyl/bibenzyl scaffolds (12–36) were designed, synthesized, and evaluated for their ability to inhibit both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). A biological evaluation showed that most of these biphenyl derivatives were potent AChE and BuChE inhibitors. Among them, compound 15 displayed the greatest ability to inhibit BuChE (IC₅₀ = 0.74 µM) and was also a good AChE inhibitor (IC₅₀ = 1.18 µM). Compound 19 was not only a potent AChE inhibitor (IC₅₀ = 0.096 µM), but also a mild BuChE inhibitor (IC₅₀ =1.25 µM). Overall, these results suggested that compound 19 may be a promising agent in the treatment of AD.

The Effect of Memantine on Cognitive Function and Behavioral and Psychological Symptoms in Mild-to-Moderate Alzheimer's Disease Patients

BACKGROUND/AIMS

Memantine has been approved by the Food and Drug Administration for the treatment of moderate-to-severe Alzheimer's disease (AD). However, the effect of memantine on patients with mild-to-moderate AD is unclear.

METHODS

This study is a post hoc analysis of a double-blind clinical trial. Donepezil was used as the standard control treatment. Outcomes included score changes from baseline to week 24 on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog), a modified 20-item Activities of Daily Living Scale (ADL), the Neuropsychiatric Inventory (NPI), and the Mini-Mental State Examination (MMSE) as well as the score of the Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC-Plus).

RESULTS

One hundred sixty-seven AD patients with an MMSE score of 10-24 were analyzed. No significant differences in the score changes from baseline to week 24 on all outcomes or the four subscales of the ADAS-cog were observed between the two treatment groups. Donepezil resulted in an improved score for naming ability on the ADAS-cog compared to memantine (p = 0.036), whereas memantine more effectively reduced agitation as measured by the NPI compared to donepezil (p = 0.039).

CONCLUSION

These findings support the efficacy of memantine for the treatment of mild-to-moderate AD, especially in patients with agitation.

Cognitive and neuropsychiatric impairments in Alzheimer's disease: current treatment strategies

This update on Alzheimer's disease (AD) discusses treatment strategies for cognitive and neuropsychiatric symptoms (such as agitation, psychosis, anxiety, and depression) common in this illness, emphasizing in particular nonpharmacologic strategies such as cognitive interventions, physical exercise, and psychotherapy. We provide an overview of cognitive enhancers and their combination strategies and medications commonly used for treatment of neuropsychiatric symptoms in AD. Finally, we give recommendations for providing support to caregivers and suggest how to identify caregiver/patient pairs most in need of intensive dementia care services.

Common psychiatric problems in cognitively impaired older patients: causes and management

Although dementias are defined by their cognitive and functional deficits, psychiatric problems are common, contribute to patient distress and caregiver burden, and precipitate institutionalization. Successful treatment involves understanding that physiologic, psychological, and environmental factors can contribute to the development of these symptoms. By carefully assessing each of these factors, clinicians can individualize treatment and flexibly use nonpharmacologic and pharmacologic approaches tailored to patients and the context of care. Although there exist limitations to many treatment options, clinicians can still adapt current knowledge to develop a multifaceted treatment approach that improves the quality of life for patients and their caregivers.

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.

Synthesis of tacrine-lophine hybrids via one-pot four component reaction and biological evaluation as acetyl- and butyrylcholinesterase inhibitors

A novel series of tacrine-lophine hybrids was synthesized and tested for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) with IC50 in the nanomolar concentration scale. The key step is the one-pot four component condensation reaction of 9-aminoalkylamino-1,2,3,4-tetrahydroacridines, benzil, different substituted aromatic aldehydes and NH4OAc, using InCl3 as the best catalyst. Tacrine-lophine hybrids were found to be potent and selective inhibitors of cholinesterases. As an extension of the four component approach to tetrasubstituted imidazoles, a new series of bis-(2,4,5-triphenyl-1H-imidazoles) or bis(n)-lophines was tested against AChE and BuChE.

Progress in frontotemporal dementia research

Frontotemporal dementia (FTD) is the second most common type of presenile dementia and is the most common form of dementia with the onset before 60 years of age. Its typical symptoms include behavioral disorders, affective symptoms, and language disorders. The FTD is a genetically and pathologically heterogeneous degenerative disorder. Animal models have provided more insights into the pathogenic mechanisms. There are currently no medications that are specifically approved for the treatment of FTD by the Food and Drug Administration. In this article, we review the recent advances in the molecular pathogenesis, pathology, animal models, and therapy for FTD. Better understanding of the pathogenesis and the use of animal models will help develop novel therapeutic strategies and provide new targets for FTD treatment.

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

Background

N-methyl-D-aspartic acid antagonists (memantine) and cholinesterase inhibitors (ChEIs) are the only two approved classes of drugs to treat dementia; this paper explores the evidence for using these two treatments in combination.

Objective

To determine the efficacy and safety of using combination therapy with memantine and a ChEI to treat dementia in comparison to monotherapy with either memantine or a ChEI.

Methods

In March 2012, we systematically searched MEDLINE/PubMed, EMBASE, Cochrane library, and grey literature databases. All study types were included, except for case series or reports, which looked at combination therapy versus monotherapy in various dementing disorders. Data was pooled for blinded randomized controlled trials (RCTs) only; mean differences and standardized mean differences were used to determine effect sizes.

Results

Thirteen studies were included in this review; 3 were blinded RCTs, with a total of 971 Alzheimer's disease (AD) patients, which were included into the meta-analysis. No papers were found that primarily addressed combination therapy in other dementias. In the meta-analysis, small but statistically significant effect sizes were seen in favor of combination therapy among patients with moderate to severe AD on the scales of cognition (0.45–0.52; p < 0.0001), scales of functional outcomes (0.23–0.3; p < 0.01), and the neuropsychiatric inventory (3.7–4.4; p < 0.0001). Among the open-label studies, 3 out of 6 suggested benefits, as did the 4 included cohort studies. However, the high risk of bias encountered in the latter two study designs limits deducing any conclusions about benefit.

Conclusion

Although there were statistically significant changes in favor of combination therapy in moderate to severe AD, heterogeneity in scales and patient characteristics exists. However, it is unclear if clinically significant outcomes can be achieved using the combination therapy. More studies are required before a recommendation for combination therapy can be made.

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.

Effects of a tacrine-8-hydroxyquinoline hybrid (IQM-622) on Aβ accumulation and cell death: involvement in hippocampal neuronal loss in Alzheimer's disease

Several studies have implicated the enzyme acetylcholinesterase (AChE) as well as several biometals in the pathogenesis of Alzheimer's disease (AD). A multifunctional molecule, the hybrid tacrine-8-hydroxyquinoline (named IQM-622), displays cholinergic, antioxidant, copper-complexing and neuroprotective properties. Using in vitro and in vivo models, we investigated the modulating effects of IQM-622 on amyloid β-protein (Aβ)-induced pathology as well as on chemically induced neurodegeneration by domoic acid. In the first experimental model, we observed a significant decrease in brain Aβ deposits in IQM-622-treated APP/Ps1 mice for four weeks. Moreover, IQM-622 promoted the degradation of intracellular Aβ in astrocytes, and protected against Aβ toxicity in cultured astrocytes and neurons. These findings suggest that the neuroprotective effect of IQM-622 is not only related to AChE inhibition, but also involves other mechanisms, including the modulation of Aβ-degradation pathways in AD brain. In this study we also compare the neuronal loss in CA1 hippocampal field of AD patients and of mice treated with domoic acid, giving similar patterns. Thus, we used a second experimental model by killing hippocampal neurons by domoic acid damage, in which IQM-622 increased survival in the CA1 and dentate gyrus regions of the hippocampus. Our observations suggest that administration of IQM-622 may have significant beneficial effects in neurodegenerative diseases, including AD, which course with acute or progressive neuronal death.

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.

Characteristics and psychosocial predictors of psychiatric emergency center transport and length of stay in patients with dementia and Alzheimer's disease: a preliminary report

BACKGROUND

Agitation and aggression are common behaviors that often lead to psychiatric emergency center (PEC) admission of nursing home patients with dementia or Alzheimer's disease. However, few if any data are available that adequately describe characteristics and psychosocial triggers of agitation and aggression leading to transport and admission to a PEC.

METHODS

A preliminary investigation to explore all possible characteristics and psychosocial predictors of PEC transport and length of stay in men and women nursing home patients with dementia or Alzheimer's disease was designed. Frequency distributions, chi-square, analyses of variance, and regression analyses were used to analyze the data.

RESULTS

One hundred PEC patient charts were reviewed, of which 58 charts were missing information and 42 charts provided evaluable data. Nursing homes located in impoverished areas transported patients to the PEC significantly more often than those in affluent areas. A disconnect between the agitated/aggressive mental state reported by nursing home staff leading to the PEC transport and the calm/cooperative mental status PEC clinicians observed during the admission process was evident. Data from the charts also showed that 74% of patients received off-label antipsychotics rather than FDA-approved medications to treat dementia or Alzheimer's disease.

CONCLUSIONS

This is one of the few studies to identify characteristics and psychosocial triggers of PEC use and length of stay in nursing home patients. We also highlight potentially dangerous antipsychotic use in dementia and Alzheimer disease. Thus, our data add to the existing knowledge base regarding PEC utilization, length of stay, and pharmacotherapy in nursing home patients with dementia and Alzheimer's disease. Given the preliminary nature of this study, however, the results should be interpreted with caution.

The efficacy of licensed-indication use of donepezil and memantine monotherapies for treating behavioural and psychological symptoms of dementia in patients with Alzheimer's disease: systematic review and meta-analysis

BACKGROUND/AIMS

Behavioural and psychological symptoms of dementia (BPSD) in Alzheimer's disease (AD) greatly increase caregiver burden. The abilities of donepezil and memantine to manage BPSD within their licensed indications in AD were compared.

METHODS

A systematic review, random effects meta-analysis and Bucher indirect comparison were conducted.

RESULTS

Six randomised controlled studies (4 donepezil and 2 memantine) reported use within the licensed indication and had Neuropsychiatric Inventory (NPI) data suitable for meta-analysis. BPSD showed significant improvement with donepezil compared with placebo [weighted mean difference (WMD) in NPI -3.51, 95% confidence interval (CI) -5.75, -1.27], whereas this was not the case for memantine (WMD -1.65, 95% CI -4.78, 1.49). WMD in NPI for donepezil versus memantine favoured donepezil but was not statistically significant (-1.86, 95% CI -5.71, 1.99; p = 0.34).

CONCLUSION

Within its licensed indication, donepezil is efficacious for the management of BPSD in AD compared with placebo.

Circadian rhythm disturbances in patients with Alzheimer's disease: a review

Circadian Rhythm Disturbances (CRDs) affect as many as a quarter of Alzheimer's disease (AD) patients during some stage of their illness. Alterations in the suprachiasmatic nucleus and melatonin secretion are the major factors linked with the cause of CRDs. As a result, the normal physiology of sleep, the biological clock, and core body temperature are affected. This paper systematically discusses some of the causative factors, typical symptoms, and treatment options for CRDs in patients with AD. This paper also emphasizes the implementation of behavioral and environmental therapies before embarking on medications to treat CRDs. Pharmacotherapeutic options are summarized to provide symptomatic benefits for the patient and relieve stress on their families and professional care providers. As of today, there are few studies relative to CRDs in AD. Large randomized trials are warranted to evaluate the effects of treatments such as bright light therapy and engaging activities in the reduction of CRDs in AD patients.

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.