Long-term cholinesterase inhibitor treatment of Alzheimer's disease

4-Oxypiperidine Ethers as Multiple Targeting Ligands at Histamine H3 Receptors and Cholinesterases

This study examines the properties of a novel series of 4-oxypiperidines designed and synthesized as histamine H3R antagonists/inverse agonists based on the structural modification of two lead compounds, viz., ADS003 and ADS009. The products are intended to maintain a high affinity for H3R while simultaneously inhibiting AChE or/and BuChE enzymes. Selected compounds were subjected to hH3R radioligand displacement and gpH3R functional assays. Some of the compounds showed nanomolar affinity. The most promising compound in the naphthalene series was ADS031, which contained a benzyl moiety at position 1 of the piperidine ring and displayed 12.5 nM affinity at the hH3R and the highest inhibitory activity against AChE (IC50 = 1.537 μM). Eight compounds showed over 60% eqBuChE inhibition and hence were qualified for the determination of the IC50 value at eqBuChE; their values ranged from 0.559 to 2.655 μM. Therapy based on a multitarget-directed ligand combining H3R antagonism with additional AChE/BuChE inhibitory properties might improve cognitive functions in multifactorial Alzheimer's disease.

Recent Progress in Research on Mechanisms of Action of Natural Products against Alzheimer's Disease: Dietary Plant Polyphenols

Alzheimer's disease (AD) is an incurable degenerative disease of the central nervous system and the most common type of dementia in the elderly. Despite years of extensive research efforts, our understanding of the etiology and pathogenesis of AD is still highly limited. Nevertheless, several hypotheses related to risk factors for AD have been proposed. Moreover, plant-derived dietary polyphenols were also shown to exert protective effects against neurodegenerative diseases such as AD. In this review, we summarize the regulatory effects of the most well-known plant-derived dietary polyphenols on several AD-related molecular mechanisms, such as amelioration of oxidative stress injury, inhibition of aberrant glial cell activation to alleviate neuroinflammation, inhibition of the generation and promotion of the clearance of toxic amyloid-β (Aβ) plaques, inhibition of cholinesterase enzyme activity, and increase in acetylcholine levels in the brain. We also discuss the issue of bioavailability and the potential for improvement in this regard. This review is expected to encourage further research on the role of natural dietary plant polyphenols in the treatment of AD.

Design, synthesis, and evaluation of N-benzylpyrrolidine and 1,3,4-oxadiazole as multitargeted hybrids for the treatment of Alzheimer's disease

Novel N-Benzylpyrrolidine hybrids were designed, synthesized, and tested against multiple in-vitro and in-vivo parameters. Among all the synthesized molecules, 8f and 12f showed extensive inhibition against beta-secretase-1 (hBACE-1), human acetylcholinesterase (hAChE) & human butyrylcholinesterase (hBuChE). These molecules are also endowed with significant AChE-peripheral anionic site (PAS) binding capability, blood-brain barrier permeability, potential disassembly of Aβ aggregates along with neuroprotection ability on SHSY-5Y cell lines. Results of the Y-Maze and Morris water maze test concluded that compounds 8f and 12f ameliorated cognitive dysfunction induced by scopolamine and Aβ. The ex-vivo activity was executed on rat's brain homogenate indicating a reduction in AChE level and oxidative stress. The pharmacokinetic investigation ascertained considerable oral absorption profile of the lead 12f. The results of the in silico docking studies and molecular dynamics simulations demonstrated stable interactions of compounds 8f and 12f with the target residues of hAChE, hBuChE and hBACE-1.

Discovery of effective phosphodiesterase 2 inhibitors with antioxidant activities for the treatment of Alzheimer's disease

The multi-target-directed-ligand (MTDL) strategy has been widely applied in the discovery of novel drugs for the treatment of Alzheimer's disease (AD) because of the multifactorial pathological mechanisms of AD. Phosphodiesterase-2 (PDE2) has been identified to be a novel and promising target for AD. However, MTDL combining with the inhibitory activity against PDE2A and other anti-AD factors such as antioxidants has not been developed yet. Herein, a novel series of PDE2 inhibitors with antioxidant capacities were designed, synthesized, and evaluated. Most compounds showed remarkable inhibitory activities against PDE2A as well as antioxidant activities. Compound 6d was selected, which showed good IC₅₀ of 6.1 nM against PDE2A, good antioxidant activity (ORAC (Trolox) = 8.4 eq.) and no cytotoxicity to SH-SY5Y cells. Molecular docking and dynamics simulations were applied for the rational design and explanation of structure-activity relationship (SAR) of lead compounds.

Strategies for Continued Successful Treatment in Patients with Alzheimer's Disease: An Overview of Switching Between Pharmacological Agents

Introduction:

Alzheimer’s disease (AD) is the most common cause of dementia, characterized by a progressive decline in cognition and function. Current treatment options for AD include the cholines-terase inhibitors (ChEIs) donepezil, galantamine, and rivastigmine, as well as the N-methyl-D-aspartate receptor antagonist memantine. Treatment guidelines recommend the use of ChEIs as the standard of care first-line therapy. Several randomized clinical studies have demonstrated the benefits of ChEIs on cogni-tion, global function, behavior and activities of daily living. However, patients may fail to achieve sus-tained clinical benefits from ChEIs due to lack/loss of efficacy and/or safety, tolerability issues, and poor adherence to the treatment. The purpose of this review is to explore the strategies for continued successful treatment in patients with AD.

Methods:

Literature search was performed for articles published in PubMed and MEDLINE, using pre-specified search terms. Articles were critically evaluated for inclusion based on their titles, abstracts, and full text of the publication.

Results and Conclusion:

The findings of this review indicate that dose up-titration and switching between ChEIs may help to improve response to ChEI treatment and also address issues such as lack/loss of effica-cy or safety/tolerability in patients with AD. However, well-designed studies are needed to provide robust evidence.

Persistence and adherence to rivastigmine in patients with dementia: Results from a noninterventional, retrospective study using the National Health Insurance research database of Taiwan

Introduction

The objective of the study was to assess adherence and persistence of patients treated with rivastigmine versus donepezil.

Methods

Persistence was calculated as the time from the first prescription date of rivastigmine/donepezil until discontinuation/medication switch/end of available data, whichever occurred first. Adherence was calculated as proportion of days covered and medication possession ratio.

Results

A majority of patients persisted on 4.5 and 6 mg of rivastigmine for 429 and 468 days, respectively, versus 443 and 441 days for patients receiving 5 and 10 mg of donepezil daily, respectively. Patients who initially received 1.5 mg of oral rivastigmine required a shorter time to reach a stable dose compared with those who initiated treatment at a higher dose of rivastigmine. Patients at a stable dose of 4.5 or 6 mg of rivastigmine were observed to persist longer than those at a lower dose of rivastigmine and donepezil.

Discussion

Although results indicate significant difference in persistence between rivastigmine and donepezil groups, clinical significance remains undetermined.

Compliance and persistence with Alzheimer's disease treatment: a retrospective analysis of multiregional hospital databases in Thailand

Aims: Due to the lack of studies evaluating compliance or persistence with Alzheimer's Disease (AD) treatment outside High-Income Countries (HICs), this study aimed to assess compliance, persistence, and factors associated with non-compliance and non-persistence by utilizing existing "real-world" information from multiregional hospital databases in Thailand.Materials and methods: Study subjects were retrospectively identified from databases of five hospitals located in different regions across Thailand. AD patients aged ≥60 years who were newly-prescribed with donepezil, galantamine, rivastigmine, or memantine between 2013 and 2017 were eligible for analysis. The Medication Possession Ratio (MPR) was used as a proxy for compliance, while the Kaplan-Meier survival analysis was employed to estimate persistence. Logistic and Cox regressions were used to assess determinants of non-compliance and non-persistence, adjusted for age and gender.Results: Among 698 eligible patients, mean (SD) MPR was 0.83 (0.25), with 70.3% of the patients compliant to the treatment (having MPR ≥ 0.80). Half of the patients discontinued their treatment (having a treatment gap >30 days) within 177 days with a 1-year persistence probability of 21.1%. The patients treated in the university-affiliated hospital were more likely to be both non-compliant (OR = 1.71; 95% CI = 1.21-2.42) and non-persistent (HR = 1.33; 95% CI = 1.12-1.58). In addition, non-compliance was higher for those prescribed with single AD treatment (OR = 2.52; 95% CI = 1.35-4.69), while non-persistence was higher for those unable to reimburse for AD treatment (HR = 1.34; 95% CI = 1.11-1.62).Limitations: By using retrospective databases, a difficulty in validating whether the medications are actually taken after being refilled may over-estimate the levels of compliance and persistence. Meanwhile, possible random coding errors may under-estimate the strength of association findings.Conclusions: This study reveals the situation of compliance and persistence on AD treatment for the first time outside HICs. The determinants of non-compliance and non-persistence underline key areas for improvement.

Benefits of statistical molecular design, covariance analysis, and reference models in QSAR: a case study on acetylcholinesterase

Scientific disciplines such as medicinal- and environmental chemistry, pharmacology, and toxicology deal with the questions related to the effects small organic compounds exhort on biological targets and the compounds' physicochemical properties responsible for these effects. A common strategy in this endeavor is to establish structure-activity relationships (SARs). The aim of this work was to illustrate benefits of performing a statistical molecular design (SMD) and proper statistical analysis of the molecules' properties before SAR and quantitative structure-activity relationship (QSAR) analysis. Our SMD followed by synthesis yielded a set of inhibitors of the enzyme acetylcholinesterase (AChE) that had very few inherent dependencies between the substructures in the molecules. If such dependencies exist, they cause severe errors in SAR interpretation and predictions by QSAR-models, and leave a set of molecules less suitable for future decision-making. In our study, SAR- and QSAR models could show which molecular sub-structures and physicochemical features that were advantageous for the AChE inhibition. Finally, the QSAR model was used for the prediction of the inhibition of AChE by an external prediction set of molecules. The accuracy of these predictions was asserted by statistical significance tests and by comparisons to simple but relevant reference models.

Drug persistency of cholinesterase inhibitors for patients with dementia of Alzheimer type in Korea

This study examined 1-year persistency with cholinesterase inhibitors (ChEIs) for the treatment of elderly Alzheimer's dementia (AD) patients in Korea. Korean Health Insurance Review & Assessment Service database from January 2005 to June 2006 was used. Patients aged 65 or older with AD diagnosis who were first prescribed a ChEI were included. The 1-year persistence, persistency rate, and switching patterns during the follow-up period were identified. Mean time to drug discontinuation was analyzed, and persistency rates between different patient factors were compared. The 1-year persistency rate of newly treated 6,461 AD patients was 24.0%, while 50% of study patients discontinued treatment by 91 days from initiation. Persistency rates of female patients (22.8%), patients in rural areas (12.7%), and primary care (10.2%) were relatively low (p < 0.001). Persistency rate differed between age groups (p < 0.001). Overall proportion of switching was 6.6%. The 1-year persistency rate of ChEIs for AD patients in Korea did not reach those of previous researches in other countries. Patients less likely to remain on therapy should be especially monitored to optimize treatment persistence.

Managing memory impairment in patients with Alzheimer’s disease

SUMMARY Memory impairment in patients with Alzheimer’s disease (AD) may be treated with cholinesterase inhibitors. Attention, alertness, initiative and memory (indirectly) may be treated with memantine. In addition to pharmacologic treatments, nonpharmacologic treatments, including external systems and devices, participation in social activities and exercise, as well as the use of habits, pictures and strategies, improve memory. We believe that although memory loss cannot be halted, both pharmacologic and nonpharmacologic treatments may help to improve AD patients’ memory and allow them to continue independent activities. Patients with mild cognitive impairment due to AD may be treated with nonpharmacologic therapies and with off-label cholinesterase inhibitors.

Behavioral animal models to assess pro-cognitive treatments for schizophrenia

Cognitive dysfunction is a core aspect of schizophrenia that constitutes a major obstacle toward reintegration of patients into society. Although multiple cognitive deficits are evident in schizophrenia patients, no medication is currently approved for their amelioration. Although consensus clinical test batteries have been developed for the assessment of putative cognition enhancers in patients with schizophrenia, parallel animal tests remain to be validated. Having no approved treatment for cognitive symptoms means no positive control can be used to examine pharmacological predictive validity of animal models. Thus, focus has been placed on animal paradigms that have demonstrable construct validity for the cognitive domain being assessed.This review describes the growing arsenal of animal paradigms under development that have putative construct validity to cognitive domains affected in schizophrenia. We discuss (1) the construct validity of the paradigms; (2) compounds developed to investigate putative treatment targets; and (3) manipulations used to first impair task performance. Focus is placed on the paradigm design, including how the use of multivariate assessments can provide evidence that main effects of treatment are not confounded by extraneous effects.

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.

A pilot study for the effects of donepezil therapy on cerebral and optic nerve head blood flow, visual field defect in normal-tension glaucoma

PURPOSE

To evaluate the effect of donepezil hydrochloride, an agent for the treatment of Alzheimer's disease (AD), on the cerebral and optic nerve head (ONH) blood flow, visual field defect in normal-tension glaucoma (NTG) patients with decreased cerebral blood flow (CBF) that demonstrates an AD-like perfusion pattern.

METHODS

The subjects were 5 NTG patients who exhibited AD-like decreased CBF upon (123)I-iodoamphetamine single photon emission computed tomography ((123)I-IMP SPECT). Donepezil hydrochloride (5 mg/day) was prescribed for each patient during a period of 12 months. Intraocular pressure (IOP), mean deviation (MD) of the Humphrey visual field, ONH blood flow determined by a laser speckle flowgraphy, and regional CBF (rCBF) determined by (123)I-IMP SPECT were measured before and every 6 months during the treatment.

RESULTS

MD, ONH blood flow, and rCBF were improved significantly after 6 months of the treatment, although IOP did not change significantly. No deterioration of NTG morbidity was found in any of the measured parameters after 12 months of the treatment.

CONCLUSIONS

Oral administration of donepezil hydrochloride in NTG patients might prevent deterioration of visual field defect, ONH blood flow, and rCBF in the temporal, parietal, and posterior lobes. This pilot study suggested the possibility that donepezil hydrochloride might ameliorate glaucomatous optic neuropathy in NTG.

Using the MATRICS to guide development of a preclinical cognitive test battery for research in schizophrenia

Cognitive deficits in schizophrenia are among the core symptoms of the disease, correlate with functional outcome, and are not well treated with current antipsychotic therapies. In order to bring together academic, industrial, and governmental bodies to address this great 'unmet therapeutic need', the NIMH sponsored the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative. Through careful factor analysis and consensus of expert opinion, MATRICS identified seven domains of cognition that are deficient in schizophrenia (attention/vigilance, working memory, reasoning and problem solving, processing speed, visual learning and memory, verbal learning and memory, and social cognition) and recommended a specific neuropsychological test battery to probe these domains. In order to move the field forward and outline an approach for translational research, there is a need for a "preclinical MATRICS" to develop a rodent test battery that is appropriate for drug development. In this review, we outline such an approach and review current rodent tasks that target these seven domains of cognition. The rodent tasks are discussed in terms of their validity for probing each cognitive domain as well as a brief overview of the pharmacology and manipulations relevant to schizophrenia for each task.

Donepezil in Alzheimer's disease: what to expect after 3 years of treatment in a routine clinical setting

BACKGROUND/AIMS

Clinical short-term trails have shown positive effects of donepezil treatment in patients with Alzheimer's disease. The outcome of continuous long-term treatment in the routine clinical settings remains to be investigated.

METHODS

The Swedish Alzheimer Treatment Study (SATS) is a descriptive, prospective, longitudinal, multicentre study. Four hundred and thirty-five outpatients with the clinical diagnosis of Alzheimer's disease, received treatment with donepezil. Patients were assessed with Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), global rating (CIBIC) and Instrumental Activities of Daily Living (IADL) at baseline and every 6 months for a total period of 3 years.

RESULTS

The mean MMSE change from baseline was positive for more than 6 months and in subgroups of patients for 12 months. After 3 years of treatment the mean change from baseline in MMSE-score was 3.8 points (95% CI, 3.0-4.7) and the ADAS-cog rise was 8.2 points (95% CI, 6.4-10.1). This is better than expected in untreated historical cohorts, and better than the ADAS-cog rise calculated by the Stern equation (15.6 points; 95% CI, 14.5-16.6). After 3 years with 38% of the patients remaining, 30% of the them were unchanged or improved in the global assessment.

CONCLUSION

Three-year donepezil treatment showed a positive global and cognitive outcome in the routine clinical setting.

Novel cholinesterase inhibitors as future effective drugs for the treatment of Alzheimer's disease

Current pharmacotherapy for Alzheimer's disease involves compounds that are aimed at increasing the levels of acetylcholine in the brain by facilitating cholinergic neurotransmission through inhibition of cholinesterase. These drugs, known as acetylcholinesterase inhibitors, have been shown to improve cognition and global functions but have little impact on improving the eventual progression of the disease; however, there is evidence that other cholinesterases such as butyrylcholinesterase can play an important role in cholinergic function in the brain, and the long-suspected non-cholinergic actions of acetylcholinesterase, mainly the interference with the beta-amyloid protein cascade, have recently driven a profound revolution in cholinesterase drug research. Several disease-modifying agents are under development that target these enzymes and have hope of becoming the next generation of effective drugs in the treatment of Alzheimer's disease.

Alzheimer's disease

BACKGROUND

The authors review the clinical features, epidemiology, pathophysiology, medical management, dental findings and dental treatment of patients with Alzheimer's disease (AD).

STUDIES REVIEWED

The authors conducted MEDLINE searches for 2000 through 2005 using the terms "Alzheimer's disease," "geriatric," "epidemiology," "pathophysiology," "treatment" and "dentistry." Reports selected for further review included those published in English in peer-reviewed journals. The authors gave preference to articles reporting randomized, controlled trials.

RESULTS

AD is a progressive and fatal neurodegenerative disorder characterized by cognitive dysfunctions, particularly in learning and memory, and the emergence of behavioral abnormalities. Deficiencies in the cells responsible for storage and processing of information underlie the cognitive, functional and behavioral changes seen in patients with the disorder.

CLINICAL IMPLICATIONS

As the elderly population grows, increasing numbers of Americans with AD will require dental treatment. The prevalence of dental disease likely will be extensive, because of diminished salivary flow and patients' inability to perform appropriate oral hygiene techniques. Preventive dental education for the caregiver and use of saliva substitutes and anticaries agents by the patient are indicated.

Treatment effects of rivastigmine on cognition, performance of daily living activities and behaviour in Alzheimer's disease in an outpatient geriatric setting

We investigated rivastigmine effectiveness in 84 Alzheimer outpatients, with a special focus on behavioural problems. Cognition, activities in daily living (ADL) and behaviour were assessed during 30 months. Changes in test results between 6 months and baseline were compared with a historical control cohort of Alzheimer patients (n = 69) by performing t-tests and calculation of Cohen's d and standardised response mean (SRM). During 6 months, rivastigmine showed effect on cognition (p < 0.001, Cohen's d = 0.33, SRM = 0.78), ADL (p < 0.001, Cohen's d = -0.43, SRM = -0.54) and memory-related behaviour (p = 0.006, Cohen's d = -0.28, SRM = -0.28). Depressive behaviour worsened (p = 0.001, Cohen's d = 0.30, SRM = 0.37) and disruptive behaviour (p = 0.369, Cohen's d = -0.07, SRM = -0.09) was not effected by rivastigmine. During 30 months, a gradual decline was shown in most domains. Most RMBPC items showed stabilization during 30 months. Improvement on disruptive behaviour items and depression items was shown after 6 months of treatment in a large proportion of patients in whom behavioural problems were present at baseline. In conclusion, a huge discontinuation rate is experienced within the first half year of treatment. In the subpopulation of patients who continued rivastigmine for 6 months, it shows modest effectiveness on cognition, functionality and memory-associated behaviour compared with historical control patients. Unfortunately, disruptive behaviour is not altered by rivastigmine therapy, and depressive behaviour worsened slightly after initial treatment. During 30 months, rivastigmine showed stabilization on numerous behaviour items as measured by the RMBPC.

Donepezil in vascular dementia: combined analysis of two large-scale clinical trials

BACKGROUND AND OBJECTIVE

There are currently no drugs approved to treat vascular dementia (VaD). The objective of this study was to determine if treatment with donepezil, an acetylcholinesterase inhibitor, may provide benefit for VaD patients.

METHODS

Combined analysis of 2 identical randomized, double-blind, placebo-controlled, 24-week studies involving 1,219 patients enrolled at 109 investigational sites in the USA, Europe, Canada and Australia. Patients were randomized to receive donepezil 5 mg/day (n = 406) or 10 mg/day (after brief titration; n = 421) or placebo (n = 392). Patients were assessed on cognition [Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), Mini-Mental State Examination (MMSE)], global function [Clinician's Interview-Based Impression of Change plus (CIBIC-plus), Clinical Dementia Rating-Sum of the Boxes (CDR-SB)] and function [Alzheimer's Disease Functional Assessment and Change Scale (ADFACS); instrumental activities of daily living (ADFACS-IADL)].

RESULTS

Both donepezil groups showed significant improvements in cognition compared with placebo (ADAS-cog, MMSE, p < 0.01). Significant global function benefits were seen on the CIBIC-plus in the 5 mg/day group (placebo vs. 5 mg/day, p < 0.001; vs. 10 mg/day, p = 0.006) and on the CDR-SB in the 10 mg/day group (placebo vs. 5 mg/day, p = 0.09; vs. 10 mg/day, p < 0.01). Significant functional benefits were also seen (ADFACS, placebo vs. 5 mg/day, p = 0.08; vs. 10 mg/day, p = 0.02; ADFACS-IADL, p < 0.05 for both donepezil groups). Donepezil was well tolerated, with low withdrawal rates due to adverse events.

CONCLUSIONS

This combined analysis of the largest trial on VaD to date showed that donepezil-treated patients had significant benefits in cognition, global function and ability to perform IADL. Based on these findings and reported tolerability, donepezil should be considered as an important therapeutic element in the overall management of patients with VaD.

QEEG monitoring of Alzheimer's disease treatment: a preliminary report of three case studies

Previous research has shown that quantitative electroencephalography (qEEG) can monitor treatment of Alzheimer's Disease (AD). This study investigated the ability of a qEEG measure based on EEG variance, combined with a delayed recognition memory task, to measure treatment effects on patients with AD. Three AD patients with very mild AD (CDR=0.5, FAST stage 3) were monitored with task specific EEG at multiple time points before and after medication treatment. Patients had their EEG recorded while performing a recognition memory task. A measure of (normalized) variance was applied to the EEG data. To the extent possible, the subjects received this treatment monitoring multiple times. These patients were monitored a total of 14 times, which yielded 11 measurements of qEEG change during the course of treatment. The direction of change in patients' qEEG values agreed with patients' medication treatment on 10 out of 11 occasions, p < 0.006 (binomial test) and was more accurate than monitoring with the relative theta power, p < 0.05. The results of this monitoring also showed that the qEEG measure accurately reflected treatment in a dose dependent manner. These results were independent of the specific medication monitored; Galantamine, Memantine, Nicotine, and Rivastigmine. In conclusion, this qEEG method may be useful for measuring AD treatment responses.

Brain plasticity and functional losses in the aged: scientific bases for a novel intervention

Aging is associated with progressive losses in function across multiple systems, including sensation, cognition, memory, motor control, and affect. The traditional view has been that functional decline in aging is unavoidable because it is a direct consequence of brain machinery wearing down over time. In recent years, an alternative perspective has emerged, which elaborates on this traditional view of age-related functional decline. This new viewpoint--based upon decades of research in neuroscience, experimental psychology, and other related fields--argues that as people age, brain plasticity processes with negative consequences begin to dominate brain functioning. Four core factors--reduced schedules of brain activity, noisy processing, weakened neuromodulatory control, and negative learning--interact to create a self-reinforcing downward spiral of degraded brain function in older adults. This downward spiral might begin from reduced brain activity due to behavioral change, from a loss in brain function driven by aging brain machinery, or more likely from both. In aggregate, these interrelated factors promote plastic changes in the brain that result in age-related functional decline. This new viewpoint on the root causes of functional decline immediately suggests a remedial approach. Studies of adult brain plasticity have shown that substantial improvement in function and/or recovery from losses in sensation, cognition, memory, motor control, and affect should be possible, using appropriately designed behavioral training paradigms. Driving brain plasticity with positive outcomes requires engaging older adults in demanding sensory, cognitive, and motor activities on an intensive basis, in a behavioral context designed to re-engage and strengthen the neuromodulatory systems that control learning in adults, with the goal of increasing the fidelity, reliability, and power of cortical representations. Such a training program would serve a substantial unmet need in aging adults. Current treatments directed at age-related functional losses are limited in important ways. Pharmacological therapies can target only a limited number of the many changes believed to underlie functional decline. Behavioral approaches focus on teaching specific strategies to aid higher order cognitive functions, and do not usually aspire to fundamentally change brain function. A brain-plasticity-based training program would potentially be applicable to all aging adults with the promise of improving their operational capabilities. We have constructed such a brain-plasticity-based training program and conducted an initial randomized controlled pilot study to evaluate the feasibility of its use by older adults. A main objective of this initial study was to estimate the effect size on standardized neuropsychological measures of memory. We found that older adults could learn the training program quickly, and could use it entirely unsupervised for the majority of the time required. Pre- and posttesting documented a significant improvement in memory within the training group (effect size 0.41, p<0.0005), with no significant within-group changes in a time-matched computer using active control group, or in a no-contact control group. Thus, a brain-plasticity-based intervention targeting normal age-related cognitive decline may potentially offer benefit to a broad population of older adults.

Similar neurocognitive performance of adults with and without a history of parental Alzheimer's disease: a pilot study

The first reported 20-year prospective follow-up of middle-aged children of Alzheimer patients failed to find statistically significant neurocognitive decline. Because that report did not include a comparison group, the current study compared the 20-year follow-up scores with scores obtained on the same 8 measures by an age-comparable sample of healthy adults without a family history of Alzheimer's disease. Both were convenience samples (n = 24). Statistical analyses (correcting for age) yielded no significant group differences in neurocognitive scores but did show a significantly higher mean score for the comparison group on the Mini-Mental State Examination (29.5 vs 28.8, P = .003, controlling for age). Even though this finding suggests that adult children of a parent with Alzheimer's disease performed well on a limited neurocognitive battery and on the Mini-Mental State Examination, the findings are preliminary and require confirmation on large representative samples with appropriate controls and long-term follow-up.

Design and synthesis of N-benzylpiperidine–purine derivatives as new dual inhibitors of acetyl- and butyrylcholinesterase

The synthesis and biological evaluation of N-benzyl-(piperidin or pyrrolidin)-purines are described. Compounds derived from N-benzylpiperidine and N-substituted purines showed moderate acetylcholinesterase inhibition. Preliminary structure-activity relationships and a superimposition of the best compound with the active conformation of donepezil have revealed structural features that have been used in the design of more potent N-benzylpiperidine inhibitors bearing an 8-substituted caffeine fragment and a methoxymethyl linker. These new compounds are interesting dual inhibitors of acetylcholinesterase and butyrylcholinesterase and have been chosen for further optimisation.

Comparison of Galantamine and Donepezil for Effects on Nerve Growth Factor, Cholinergic Markers, and Memory Performance in Aged Rats

This study was designed to determine 1) whether repeated exposures to the acetylcholinesterase inhibitors (AChEIs) galantamine (GAL) or donepezil (DON) resulted in positive effects on nerve growth factor (NGF) and its receptors, cholinergic proteins, and cognitive function in the aged rat, and 2) whether GAL had any advantages over DON given its allosteric potentiating ligand (APL) activity at nicotinic acetylcholine receptors. Behavioral tests (i.e., water maze and light/dark box) were conducted in aged Fisher 344 rats during 15 days of repeated (subcutaneous) exposure to either GAL (3.0 or 6.0 mg/kg/day) or DON (0.375 or 0.75 mg/kg/day). Forty-eight hours after the last drug injection, cholinergic receptors were measured by [(125)I]-(+/-)-exo-2-(2-iodo-5-pyridyl)-7-azabicyclo[2.2.1]heptane ([(125)I]IPH; epibatidine analog), (125)I-alpha-bungarotoxin ((125)I-BTX), [(3)H]pirenzepine ([(3)H]PRZ), and [(3)H]-5,11-dihydro-11-[((2-(2-((dipropylamino)methyl)-1-piperidinyl)ethyl)amino)carbonyl]-6H-pyrido(2,3-b)(1,4)-benzodiazepin-6-one methanesulfonate ([(3)H]AFDX-384, or [(3)H]AFX) autoradiography. Immunochemical methods were used to measure NGF, high (TrkA and phospho-TrkA)- and low (p75 neurotrophin receptor)-affinity NGF receptors, choline acetyltransferase (ChAT), and the vesicular acetylcholine transporter (VAChT) in memory-related brain regions. Depending on dose, both GAL and DON enhanced spatial learning (without affecting anxiety levels) and increased [(125)I]IPH, [(3)H]PRZ, and [(3)H]AFX (but decreased (125)I-BTX) binding in some cortical and hippocampal brain regions. Neither AChEI was associated with marked changes in NGF, NGF receptors, or VAChT, although DON did moderately increase ChAT in the basal forebrain and hippocampus. The results suggest that repeated exposures to either GAL or DON results in positive (and sustained) behavioral and cholinergic effects in the aged mammalian brain but that the APL activity of GAL may not afford any advantage over acetylcholinesterase inhibition alone.

One-year treatment of Alzheimer's disease with acetylcholinesterase inhibitors: improvement on ADAS-cog and TMT A, no change or worsening on other tests

The aim of this study was to assess cognitive functioning measured by selected psychometric and neuropsychological tools in patients with Alzheimer's disease (AD) after 1-year treatment with acetylcholinesterase inhibitors. Seventy-six patients (22 male and 54 female) with a mild to moderate stage of AD, aged 56-86 (mean 68) years, were treated. Forty-seven received donepezil (mean dose 9.3 mg/d) and 29 rivastigmine (mean dose 8.5 mg/d). Cognitive measurements included: the mini mental state examination (MMSE), the Alzheimer disease assessment scale-cognitive (ADAS- cog), the trail making test (TMT) and the Stroop color word interference test. The assessments were made before and after 3, 6 and 12 months of treatment. A significant improvement in ADAS-cog (p < 0.001, 83% of patients improved) and a worsening in MMSE (84% of patients worsened, p < 0.01 after 6 and 12 months) was noted after the 1 year treatment. A majority of patients (57%) improved in the TMT-A (p < 0.001), measuring psychomotor speed and worsened in the TMT-B (p < 0.01, after 12 months), and Stroop B test (p < 0.001), measuring working memory and executive functions, 53% and 61%, respectively. Most patients (83%) did not change their performance in the Stroop A (improvement after 3 months, p < 0.001, worsening after 6 and 12 months p < 0.01) test measuring verbal abilities, after 1 year treatment. The results obtained suggest that the treatment with cholinergic drugs may improve global cognitive functioning (ADAS-cog) and psychomotor speed (TMT A), however, such treatment is unable to prevent the deterioration of working memory and executive functions.

EEG detection of early Alzheimer's disease using psychophysical tasks

In this study, we hypothesized that a quantitative EEG (qEEG) method for measuring EEG variability combined with specific psychophysical tasks could improve the classification accuracy of subjects with normal aging vs. mild cognitive impairment (MCI) or mild dementia due to Alzheimer's Disease and Related Disorders (ADRD). The cross-sectional sample consisted of 48 subjects (32 normal aging and 16 ADRD: n = 3 mild dementia, n = 13 MCI FAST stage 3). During EEG recording, subjects performed two visual, delayed recognition memory tasks as well as a task that tested their ability to perceive structure-from-motion (SFM). These EEG data were used to compute qEEG measures of the (normalized) variance of posterior cortical activity during the first 150 milliseconds (ms) after stimulus onset and the variance of anterior cortical activity during the second 150 ms epoch. The ratio, anterior/posterior cerebral qEEG value, was then computed for each subject, and the optimal cutoff value identified to discriminate normal from impaired subjects. An optimal qEEG cutoff value for the delayed recognition memory tasks correctly discriminated 30 of the 32 normal aging subjects (94% specificity) and 14 of 16 MCI-to-mild ADRD subjects (88% sensitivity). On the other hand, the application of this qEEG measure to EEG data recorded while subjects performed a SFM task did not distinguish between ADRD and normal aging any better than chance. In conclusion, this qEEG measure is specific to the psychophysical task being performed by the subject. When it was combined with delayed recognition memory tasks, it yielded results that are comparable to the accuracies reported by PET scan studies of normal aging vs. AD with mild cognitive impairment. These results warrant further evaluation.