Adverse effects associated with the use of donepezil in general practice in England

Taming neuroinflammation in Alzheimer's disease: The protective role of phytochemicals through the gut-brain axis

Alzheimer's disease (AD) is a progressive degenerative neurological condition characterized by cognitive decline, primarily affecting memory and logical thinking, attributed to amyloid-β plaques and tau protein tangles in the brain, leading to neuronal loss and brain atrophy. Neuroinflammation, a hallmark of AD, involves the activation of microglia and astrocytes in response to pathological changes, potentially exacerbating neuronal damage. The gut-brain axis is a bidirectional communication pathway between the gastrointestinal and central nervous systems, crucial for maintaining brain health. Phytochemicals, natural compounds found in plants with antioxidant and anti-inflammatory properties, such as flavonoids, curcumin, resveratrol, and quercetin, have emerged as potential modulators of this axis, suggesting implications for AD prevention. Intake of phytochemicals influences the gut microbial composition and its metabolites, thereby impacting neuroinflammation and oxidative stress in the brain. Consumption of phytochemical-rich foods may promote a healthy gut microbiota, fostering the production of anti-inflammatory and neuroprotective substances. Early dietary incorporation of phytochemicals offers a non-invasive strategy for modulating the gut-brain axis and potentially reducing AD risk or delaying its onset. The exploration of interventions targeting the gut-brain axis through phytochemical intake represents a promising avenue for the development of preventive or therapeutic strategies against AD initiation and progression.

Galantamine-Induced Third-Degree Heart Block

Galantamine is commonly used to manage symptoms of Alzheimer's disease and other cognitive disorders. While it is generally well-tolerated, cardiovascular side effects are rare but can be serious. We report the case of a patient who developed a third-degree heart block after initiating galantamine therapy. This case highlights the importance of monitoring patients for cardiac adverse effects when using galantamine and the need for prompt intervention when such effects occur.

The Effect of a Tribulus-Based Formulation in Alleviating Cholinergic System Impairment and Scopolamine-Induced Memory Loss in Zebrafish (Danio rerio): Insights from Molecular Docking and In Vitro/In Vivo Approaches

Tribulus terrestris L. (Tt) has been recently gaining attention for its pharmacological value, including its neuroprotective activities. In this study, we explore the neuroprotective effects of a Tribulus terrestris extract in a zebrafish (Danio rerio) model of scopolamine (SCOP)-induced memory impairment and brain oxidative stress. SCOP, an anticholinergic drug, was employed to replicate fundamental aspects of Alzheimer's disease (AD) in animal models. The fish were treated with ethanolic leaf extract (ELE) from Tt (1, 3, and 6 mg/L) for 15 days. SCOP (100 µM) was administered 30 min before behavioral tests were conducted. Molecular interactions of the major compounds identified via UPLC-PDA/MS in Tt fractions with the active site of acetylcholinesterase (AChE) were explored via molecular docking analyses. Terrestrosin C, protodioscin, rutin, and saponin C exhibited the most stable binding. The spatial memory performance was assessed using the Y-maze test, and memory recognition was examined using a novel object recognition (NOR) test. Tt extract treatment reversed the altered locomotion patterns that were caused by SCOP administration. Biochemical analyses also verified Tt's role in inhibiting AChE, improving antioxidant enzyme activities, and reducing oxidative stress markers. The present findings pave the way for future application of Tt as a natural alternative to treat cognitive disorders.

Microbiota-gut-brain axis and related therapeutics in Alzheimer's disease: prospects for multitherapy and inflammation control

Alzheimer's disease (AD) is the most common type of dementia in the elderly and causes neurodegeneration, leading to memory loss, behavioral disorder, and psychiatric impairment. One potential mechanism contributing to the pathogenesis of AD may be the imbalance in gut microbiota, local and systemic inflammation, and dysregulation of the microbiota-gut-brain axis (MGBA). Most of the AD drugs approved for clinical use today are symptomatic treatments that do not improve AD pathologic changes. As a result, researchers are exploring novel therapeutic modalities. Treatments involving the MGBA include antibiotics, probiotics, transplantation of fecal microbiota, botanical products, and others. However, single-treatment modalities are not as effective as expected, and a combination therapy is gaining momentum. The purpose of this review is to summarize recent advances in MGBA-related pathological mechanisms and treatment modalities in AD and to propose a new concept of combination therapy. "MGBA-based multitherapy" is an emerging view of treatment in which classic symptomatic treatments and MGBA-based therapeutic modalities are used in combination. Donepezil and memantine are two commonly used drugs in AD treatment. On the basis of the single/combined use of these two drugs, two/more additional drugs and treatment modalities that target the MGBA are chosen based on the characteristics of the patient's condition as an adjuvant treatment, as well as the maintenance of good lifestyle habits. "MGBA-based multitherapy" offers new insights for the treatment of cognitive impairment in AD patients and is expected to show good therapeutic results.

Thiazolidin-4-one prevents against memory deficits, increase in phosphorylated tau protein, oxidative damage and cholinergic dysfunction in Alzheimer disease model: Comparison with donepezil drug

Alzheimer's disease (AD) is characterized mostly by memory decline. The current therapeutic arsenal for treating AD is limited, and the available drugs only produce symptomatic benefits, but do not stop disease progression. The search for effective therapeutic alternatives with multitarget actions is therefore imperative. One such a potential alternative is thiazolidin-4-one, a compound that exhibits anti-amnesic, anticholinesterase, and antioxidant activities. The aim of this study was evaluated the effects of 2-(4-(methylthio)phenyl)- 3-(3-(piperidin-1-yl)propyl) thiazolidin-4-one (DS12) on memory and neurochemical parameters in a model of AD induced by an intracerebroventricular injection of streptozotocin (STZ). Adult male rats were divided into five groups: I, control (saline); II, DS12 (10 mg/kg); III, STZ; IV, STZ + DS12 (10 mg/kg); V, STZ + donepezil (5 mg/kg). The rats were orally treated with DS12 and donepezil for a period of 20 days. Memory, acetylcholinesterase (AChE) activity, phosphorylated tau protein levels and oxidative stress were analyzed in the cerebral cortex, hippocampus, and cerebellum. Biochemical and hematological parameters were evaluated in the blood and serum. Memory impairment and the increase in AChE activity and phosphorylated tau protein level induced by STZ were prevented by DS12 and donepezil treatment. Streptozotocin induces an increase in reactive oxygen species levels and a decrease in catalase activity in the hippocampus, cerebral cortex, and cerebellum. DS12 treatment conferred protection from oxidative alterations in all brain structures. No changes were observed in serum biochemical parameters (glucose, triglycerides, cholesterol, uric acid, and urea) or hematological parameters, such as platelets, lymphocytes, hemoglobin, hematocrit, and total plasma protein. DS12 improved memory and neurochemical changes in an AD model and did not show toxic effects, suggesting the promising therapeutic potential of this compound.

M1/M4-Preferring Muscarinic Cholinergic Receptor Agonist Xanomeline Reverses Wake and Arousal Deficits in Nonpathologically Aged Mice

Degeneration of the cholinergic basal forebrain is implicated in the development of cognitive deficits and sleep/wake architecture disturbances in mild cognitive impairment (MCI) and Alzheimer's disease (AD). Indirect-acting muscarinic cholinergic receptor agonists, such as acetylcholinesterase inhibitors (AChEIs), remain the only FDA-approved treatments for the cognitive impairments observed in AD that target the cholinergic system. Novel direct-acting muscarinic cholinergic receptor agonists also improve cognitive performance in young and aged preclinical species and are currently under clinical development for AD. However, little is known about the effects of direct-acting muscarinic cholinergic receptor agonists on disruptions of sleep/wake architecture and arousal observed in nonpathologically aged rodents, nonhuman primates, and clinical populations. The purpose of the present study was to provide the first assessment of the effects of the direct-acting M1/M4-preferring muscarinic cholinergic receptor agonist xanomeline on sleep/wake architecture and arousal in young and nonpathologically aged mice, in comparison with the AChEI donepezil, when dosed in either the active or inactive phase of the circadian cycle. Xanomeline produced a robust reversal of both wake fragmentation and disruptions in arousal when dosed in the active phase of nonpathologically aged mice. In contrast, donepezil had no effect on either age-related wake fragmentation or arousal deficits when dosed during the active phase. When dosed in the inactive phase, both xanomeline and donepezil produced increases in wake and arousal and decreases in nonrapid eye movement sleep quality and quantity in nonpathologically aged mice. Collectively, these novel findings suggest that direct-acting muscarinic cholinergic agonists such as xanomeline may provide enhanced wakefulness and arousal in nonpathological aging, MCI, and AD patient populations.

Synthesis of novel benzothiazole derivatives and investigation of their enzyme inhibitory effects against Alzheimer's disease

The use of dual acetylcholinesterase (AChE)-monoamine oxidase B (MAO-B) inhibitors is a new approach in the treatment of Alzheimer disease (AD). In this work, 14 new benzothiazoles (4a-4n) were designed and synthesized. In biological activity studies, the AChE, butyrylcholinesterase (BChE), MAO-A and MAO-B inhibitory potentials of all compounds were evaluated using the in vitro fluorometric method. Additionally, amyloid beta (Aβ)-aggregation inhibitory effects of active compounds were evaluated by means of an in vitro kit-based method. The biological evaluation showed that compounds 4a, 4d, 4f, 4h, 4k and 4m displayed significant activity against AChE and MAO-B enzymes. Compound 4f displayed inhibitory activity against AChE and MAO-B enzyme with IC50 values of 23.4 ± 1.1 nM and 40.3 ± 1.7 nM, respectively. It has been revealed that compound 4f may have the potential to inhibit AChE and MAO-B enzymes, as well as the ability to prevent the formation of beta amyloid plaques accumulated in the brains of patients suffering from AD. In silico studies also support the obtained biological activity findings. Compound 4f provided strong interactions with the active site of both enzymes. In particular, the interaction of compound 4f with flavin adenine dinucleotide (FAD) in the MAO-B enzyme active site is a promising and exciting finding.

A Multinational, Multicenter, Randomized, Double-Blind, Active Comparator, Phase III Clinical Trial to Evaluate the Efficacy and Safety of Donepezil Transdermal Patch in Patients With Alzheimer's Disease

Background and Purpose

Oral administration of cholinesterase inhibitors is often associated with adverse gastrointestinal effects, and so developing an alternative administration route, such as transdermal, is urgently needed. The primary objective of this study was to determine the efficacy and safety of the IPI-301 donepezil transdermal patch compared with donepezil tablets (control) in mild-to-moderate probable Alzheimer’s disease (AD).

Methods

This prospective, randomized, double-blind, double-dummy, two-arm parallel, multicenter trial included 399 patients, among whom 303 completed the trial. For randomization, the patients were stratified based on previous treatment and donepezil dose; patients in each stratum were randomized to the test and control groups at a 1:1 ratio.

Results

The difference between the control group and the IPI-301 group, quantified as the Hodges–Lehmann estimate of location shift, was 0.00 (95% confidence interval: -1.00 to 1.33), with an upper limit of less than 2.02. The change in Alzheimer’s Disease Cooperative Study–Activities of Daily Living (ADCS-ADL) score differed significantly between the IPI-301 and control groups (p=0.02). However, the changes in the full-itemized ADCS-ADL scores at week 24 did not differ significantly between the two groups. There were no differences between the two groups regarding the scores for the Clinician Interview-Based Impression of Change (p=0.9097), Mini-Mental State Examination (p=0.7018), Neuropsychiatric Inventory (p=0.7656), or Clinical Dementia Rating (p=0.9990). Adverse events, vital signs, and laboratory test results were comparable between the two groups.

Conclusions

IPI-301 was safe and efficacious in improving cognitive function in patients with mild-to-moderate AD.

Association of cognitive enhancers and incident seizure risk in dementia: a population-based study

Background

Although individuals with dementia have a high risk of developing seizures, whether seizures are associated with cholinesterase inhibitors, which are commonly prescribed to treat individuals with dementia, remains unknown. This study investigated the risk of incident seizure following cholinesterase inhibitor use in patients with dementia.

Methods

A nationwide, nested case-control study was conducted using data from the Korean Health Insurance Review and Assessment Service (HIRA) from 2014 through 2018. A total of 13,767 participants aged 65–95 years who experienced incident seizure were propensity score-matched for medical comorbidities and drug exposure at a 1:3 ratio with a control group of 39,084 participants. The study examined the incidence of seizures in patients diagnosed with dementia within one year after receiving cognitive enhancers. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for seizure incidence according to cholinesterase inhibitor use were analyzed using a multivariable conditional logistic regression model.

Results

There was no statistically significant association between duration of cholinesterase inhibitors use and seizure risk. Although there was slight increased seizure risk in patient after receiving donepezil for 1 year compared to memantine, subgroup analyses stratified age and sex did not reveal any significant association between cholinesterase inhibitors use and late-onset seizure.

Conclusions

Our findings suggest no immediate increase in seizure risk is associated with cholinesterase inhibitor use, although the risk of seizure in patients with dementia did increase after one year of continued medication intake. Further study is required to obtain confirmatory results on the seizure-related safety of cognitive enhancers in patients with dementia.

Occurrence of acute cholinergic syndrome in an infant due to donepezil ingestion

Donepezil and acetyl cholinesterase inhibitors are the most commonly prescribed medications for the treatment of Alzheimer's disease. We describe a 2-year-old infant who was referred to the emergency department after developing cholinergic syndrome 6 hours after ingesting 10 mg of his grandmother's donepezil tablets and was finally discharged in stable condition.

Microwave-assisted rapid synthesis of spirooxindole-pyrrolizidine analogues and their activity as anti-amyloidogenic agents

A library of Sox-pyrrolizidines was rapidly prepared by microwave-assisted, one-pot, three-component, 1,3-dipolar cycloaddition of azomethine ylides from l-proline and isatin, with various β-nitrostyrenes. Nitro-Sox compounds, 4b, 4d and 4e inhibit HEWL amyloid fibril formation by ThT studies with percentages of fluorescence intensity of 55.4, 42.9 and 40.3%, respectively. Further studies with MTT assay, Raman spectroscopy, TEM and molecular docking supported these promising candidates for activity against amyloid misfolding, a phenomenon leading to Alzheimer's disease pathology.

The Neuroinflammasome in Alzheimer's Disease and Cerebral Stroke

Aim/Background

This review investigated a patient with Alzheimer's disease (AD) treated with 4,4′-diaminodiphenyl sulfone (DDS) as a neuroinflammasome competitor.

Methods

We monitored AD's progression through numeric clinical staging (NCS) with a new biomarker. NCS was determined by the presence of AD symptoms and neuropsychiatric (NP) symptoms caused by anti-AD (AAD) drugs (D) as a biomarker. We also monitored the function of DDS for stroke in a no-intake emergency state.

Results

By introducing (D), AD's progression was monitored through NCS staging. AAD side effects and neuropsychiatric symptoms were identified. DDS was stopped in patients with stroke with NCS 6 caused by AAD, and it rapidly proceeded to cerebral infarct.

Conclusions

AAD can occasionally exacerbate AD and stroke. DDS can alleviate mild cognitive impairment (MCI), early AD and stroke. We clinically confirmed the role of DDS as a neuroinflammasome competitor after stroke. DDS preserved neuronal survival within 24–55 h in the Seoul Study cohort.

Synthetic β-hydroxy ketone derivative inhibits cholinesterases, rescues oxidative stress and ameliorates cognitive deficits in 5XFAD mice model of AD

Alzheimer's disease (AD) is a progressive, chronic and age-related neurodegenerative disorder that affects millions of people across the world. In pursuit of new anti-AD remedies, 2-[Hydroxy-(4-nitrophenyl)methyl]-cyclopentanone (NMC), a β hydroxyl ketone derivative was studied to explore its neuroprotective potentials against AD. The in-vitro AChE and BuChE enzymes inhibition were evaluated by Ellman protocol and antioxidant potentials of NMC by DPPH free radical scavenging assay. In-vivo behavioral studies were performed in the transgenic 5xFAD mice model of AD using shallow water maze (SWM), Paddling Y-Maze (PYM), elevated plus maze (EPM) and balance beam (BB) tests. Also, the ex-vivo cholinesterase inhibitory effects of NMC and histopathological analysis of amyloid-β plaques were determined in the frontal cortex and hippocampal regions of the mice brain. NMC exhibited significant in vitro anti-cholinesterase enzyme potentials with an IC₅₀ value of 67 μg/ml against AChE and 96 μg/ml against BuChE respectively. Interestingly, the activities of AChE and BuChE enzymes were also significantly lower in the cortex and hippocampus of NMC-treated groups. Also, in the DPPH assessment, NMC displayed substantial antioxidant properties with an IC₅₀ value observed as 171 μg/ml. Moreover, histopathological analysis via thioflavin-s staining displayed significantly lower plaques depositions in the cortex and hippocampus region of NMC-treated mice groups. Furthermore, SWM, PYM, EPM, and BB behavioral analysis indicated that NMC enhanced spatial learning, memory consolidation and improved balance performance. Altogether, to the best of our knowledge, we believe that NMC may serve as a potential and promising anti-cholinesterase, antioxidant and neuroprotective agent against AD.

Evaluation of the Adverse Effects of Chronic Exposure to Donepezil (An Acetylcholinesterase Inhibitor) in Adult Zebrafish by Behavioral and Biochemical Assessments

Donepezil (DPZ) is an acetylcholinesterase inhibitor used for the clinical treatment of mild cognitive impairment. However, DPZ has been reported to have adverse effects, including causing abnormal cardiac rhythm, insomnia, vomiting, and muscle cramps. However, the existence of these effects in subjects without Dementia is unknown. In this study, we use zebrafish to conduct a deeper analysis of the potential adverse effects of DPZ on the short-term memory and behaviors of normal zebrafish by performing multiple behavioral and biochemical assays. Adult zebrafish were exposed to 1 ppm and 2.5 ppm of DPZ. From the results, DPZ caused a slight improvement in the short-term memory of zebrafish and induced significant elevation in aggressiveness, while the novel tank and shoaling tests revealed anxiolytic-like behavior to be caused by DPZ. Furthermore, zebrafish circadian locomotor activity displayed a higher reduction of locomotion and abnormal movement orientation in both low- and high-dose groups, compared to the control group. Biomarker assays revealed that these alterations were associated with an elevation of oxytocin and a reduction of cortisol levels in the brain. Moreover, the significant increases in reactive oxygen species (ROS) and malondialdehyde (MDA) levels in muscle tissue suggest DPZ exposure induced muscle tissue oxidative stress and muscle weakness, which may underlie the locomotor activity impairment. In conclusion, we show, for the first time, that chronic waterborne exposure to DPZ can severely induce adverse effects on normal zebrafish in a dose-dependent manner. These unexpected adverse effects on behavioral alteration should be carefully addressed in future studies considering DPZ conducted on zebrafish or other animals.

Development of donepezil-induced hypokalemia following treatment of cognitive impairment

Donepezil is a cholinesterase inhibitor used extensively to treat Alzheimer disease. The increased cholinergic activity is associated with adverse effects, therefore gastrointestinal symptoms, including nausea, vomiting, and diarrhea, are common. Hypokalemia is a rare adverse event that occurs in less than 1% of donepezil-treated patients. Although hypokalemia of mild and moderate grade does not present serious signs and symptoms, severe hypokalemia often results in prolonged hospitalization and mortality. Herein, we report a case of hypokalemia developed after the initiation of donepezil therapy for cognitive impairment.

Epalrestat improves motor symptoms by reducing oxidative stress and inflammation in the reserpine induced mouse model of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting a large number of elderly people worldwide. The current therapies for PD are symptom-based; they do not provide a cure but improve the quality of life. Muscular dysfunction is the hallmark clinical feature of PD and oxidative stress and inflammation play a critical role in its pathogenesis. Epalrestat is used for the treatment of diabetic neuropathy and is known to improve antioxidative defense mechanisms in the CNS. Therefore, in this study, we investigated the role of Epalrestat in the reserpine induced mouse model of PD.

METHOD

We used Swiss Albino mice for the PD model and tested for akinesia/bradykinesia, muscular rigidity, palpebral ptosis, and tremor, as well as conducting swim and open field tests. Brain samples were used to determine oxidative stress parameters and infiltration of immune cells.

RESULTS

Epalrestat treatment significantly improved akinesia and bradykinesia, muscular dysfunctions, tremor level, and gait functions compared to the reserpine group. It also improved the latency in the swim test. Eplarestat significantly reduced lipid peroxidation and NO concentration in different brain tissues and increased the activity of antioxidative enzymes, glutathione, catalase, and superoxide dismutase. Furthermore, Epalrestat reduced neuroinflammation by reducing the number of infiltrating immune cells.

CONCLUSION

Eplarestat improves muscular dysfunction in PD by reducing oxidative stress and inflammation.

The fruit of Crataegus pinnatifida ameliorates memory deficits in β-amyloid protein-induced Alzheimer's disease mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Crataegus pinnatifida is a traditional medicine widely used as digestive drug in East Asia. Although Chinese herbal medicine used it for mental health, scientific evidence does not exist, yet.

AIMS OF STUDY

The aim of this study is to show that the ethanol extract of the fruit of Crataegus pinnatifida (CPE) has neuroprotective effect on Alzheimer' disease model mice.

MATERIALS AND METHODS

Intracerebroventricular injection of Aβ was used to induce Alzheimer's disease-like pathology. Passive avoidance and Y-maze tasks were used to examine the effect of CPE on memory impairments by Aβ. Immunohistochemistry was used to examine the effect of CPE on glial activation. ThT assay was used to observe the effect of CPE on Aβ aggregation. MTT and LDH release assays were utilized to examine effects of CPE on Aβ-induced cytotoxicity.

RESULTS

CPE prevented memory deficit in Aβ-induced memory impairment model. Moreover, CPE prevented glial activation in the hippocampus of Aβ-injected model. In in vitro test, CPE inhibited Aβ fibril formation in a concentration-dependent manner. CPE also caused disaggregation of Aβ fibrils. Along with this, CPE blocked neuronal cell death induced by Aβ.

CONCLUSIONS

Collectively, these experimental findings demonstrated that CPE could be a candidate for development of AD therapy.

Ameliorative effect of deoxyvasicine on scopolamine-induced cognitive dysfunction by restoration of cholinergic function in mice

BACKGROUND

Aerial parts of Peganum harmala Linn is used as a traditional medical herb for treatment of amnesia in Uighur medicine in China. Deoxyvasicine (DVAS) is one of the chief active ingredients in P. harmala, it possesses strong acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities in vitro, but the therapeutic effect and mechanisms on amnesia in vivo are unclear.

PURPOSE

The objective of this study was to investigate the improvement effect of DVAS from P. harmala in learning and memory deficits of scopolamine-induced mice and elucidate the underlying mechanisms involved.

METHODS

Mice were pretreated with DVAS (5, 15 and 45 mg/kg) and huperzine-A (0.2 mg/kg) by gavage for 7 days, and subsequently were daily intraperitoneally injected with scopolamine (1 mg/kg) to induce learning and memory deficits and behavioral performance was assessed by Morris water maze. To further evaluate the potential mechanisms of DVAS in improving learning and memory capabilities, pathological change, levels of various biochemical markers and protein expressions related to cholinergic system, oxidative stress, and neuroinflammation were examined.

RESULTS

The results showed that DVAS could alleviate learning and memory deficits in scopolamine-treated mice. DVAS could regulate cholinergic function by inhibiting AChE and activating choline acetyltransferase (ChAT) activities and protein expressions. DVAS could induce brain-derived neurotrophic factor and protect hippocampal pyramidal cells against neuronal damage. DVAS also enhanced antioxidant defense via increasing the antioxidant enzyme level and activity of glutathione peroxidase, and anti-inflammatory function through suppressing tumor necrosis factor-α. Additionally, DVAS could regulate the neurotransmitters by elevating acetylcholine, 5-hydroxytryptamine, γ-aminobutyric acid and reducing 5-hydroxyindole-3-acetic acid and glutamic acid.

CONCLUSION

Results illustrated that DVAS may be a promising candidate compound against amnesia via restoration of cholinergic function, regulating neurotransmitters, attenuating neuroinflammation and oxidative stress.

One-Year Persistence with Donepezil, Memantine, and Rivastigmine in More than 66,000 Elderly Patients Followed in Poland

BACKGROUND

Previous studies have suggested that there are substantial differences between countries in terms of persistence with antidementia drugs and that the management of dementia is likely to be population-specific.

OBJECTIVE

The aim of this study was to analyze the one-year persistence with donepezil, memantine, and rivastigmine in more than 66,000 elderly patients followed in Poland.

METHODS

This study included patients who were prescribed donepezil, memantine, or rivastigmine for the first time in general and neuropsychiatric practices in Poland between September 2016 and December 2017 (index date; N = 66,030). The primary outcome of the study was the one-year persistence with donepezil, memantine, and rivastigmine. Non-persistence was defined as a gap of at least 90 days without anti-dementia therapy. The secondary outcome was the identification of variables significantly associated with treatment non-persistence.

RESULTS

After 12 months of follow-up, 42.2% of donepezil users, 46.0% of rivastigmine users, and 65.9% of memantine users were persistent (log-rank p-value <0.001). Memantine (hazard ratio [HR] = 0.58) and rivastigmine users (HR = 0.92) were less likely to discontinue treatment one year after initiation than donepezil users. Furthermore, a younger age (60-64 years: HR = 1.32; 65-74 years: HR = 1.13) and therapy initiated by a neuropsychiatrist (HR = 1.11) were positively associated with therapy discontinuation, while we observed a negative association between the prescription of anti-psychotic drugs and non-persistence (HR = 0.81).

CONCLUSION

One-year persistence with donepezil, memantine, and rivastigmine was low in elderly patients followed in Poland, and was influenced by age, physician specialty, and co-therapy.

Seizure in Alzheimer's Disease: An Underestimated Phenomenon

Alzheimer's disease (AD) is considered as a potential risk factor for the development of seizure due to neurodegeneration and imbalance between stimulatory and inhibitory circuits in the brain. Seizure could occur in any point during the course of AD, and its presentation varies from fluctuation in cognitive domains to more typical seizures. The clinical diagnosis of seizure in patients with dementia may be challenging due to difficulty in history taking and clinical assessment. No paraclinic methods other than electroencephalogram (EEG) could provide arguments for the diagnosis of AD-related seizures (neither imaging modalities nor cerebrospinal fluid biomarkers). Standard 30-minute EEG may not be sufficiently sensitive to detect epileptiform discharges. In the present study, we aim to review different aspects of seizure in AD, including seizure prevalence, risk factors, underlying mechanisms, electroencephalographic findings, clinical presentations, impact of seizures on AD, and treatment options.

Reality orientation therapy benefits cognition in older people with dementia: A meta-analysis

BACKGROUND/AIMS

To investigate the effect of reality orientation therapy on cognition, behavioral problems, and depressive symptoms in older people with dementia.

DESIGN

Meta-analysis of randomized controlled trials (RCTs).

DATA SOURCE

Various electronic databases were searched to select eligible articles, which included CINAHL, Embase, Pubmed, ProQuest, PsycINFO, the Cochrane Central Register of Controlled Trials, Google Scholar and Chinese electronic databases comprising Chinese Electronic Periodical Services and China Knowledge Resource Integrated.

REVIEW METHODS

Two reviewers independently extracted data and evaluated the methodological quality of the included articles. All analyses were performed using a random-effects model. Moderator analyses were conducted to identify the superior subgroup of intervention details that benefited from reality orientation therapy.

RESULTS

There was an overall random effect of reality orientation therapy of improving cognitive functions (n = 11, g = 0.39, 95% confidence interval [CI] = 0.25, 0.53); however, reality orientation therapy did not ameliorate behavioral problems (n = 5, g= -0.18, 95% CI= -0.36, 0.00) and depressive symptoms (n = 5, g= -0.17, 95% CI= -0.39, 0.05). A subgroup analysis revealed that studies of reality orientation therapy alone had a greater improvement in cognitive functions compared to those studies adopting reality orientation therapy combined with other types of techniques, but the difference in effect sizes between the two approaches was not significant (g = 0.51 vs. 0.35, p = 0.333).

CONCLUSIONS

Reality orientation therapy can be considered routine care for the maintenance and improvement of cognitive functions in older populations with dementia. Health professionals and caregivers can be further educated and trained to regularly perform reality orientation therapy to improve the cognition of older people with dementia.

The ameliorating effect of 1-palmitoyl-2-linoleoyl-3-acetylglycerol on scopolamine-induced memory impairment via acetylcholinesterase inhibition and LTP activation

In the present study, we investigated whether 1-palmitoyl-2-linoleoyl-3-acetylglycerol (PLAG), a component of antlers of Cervus nippon Temminck, would have memory-ameliorating properties against cholinergic blockade-induced memory impairment in mice. In the passive avoidance task to investigate the effects of PLAG on long-term memory, PLAG (10mg/kg, p.o.) administration ameliorated scopolamine-induced memory impairment. PLAG also reversed the impairments of working memory in the Y-maze task and spatial memory as shown in the Morris water maze. To identify the mechanism of the memory-ameliorating effect of PLAG, acetylcholinesterase (AChE) inhibition assay and the Western blot analysis were conducted. In the AChE inhibition assay, PLAG inhibited the AChE activity in mice and PLAG increased the expression levels of phosphorylated CaMKII, ERK, and CREB in the hippocampus. Additionally, long-term potentiation (LTP) of synaptic strength occurred by PLAG treatment in the hippocampal cultures. Overall, the present study suggests that PLAG reversed memory deficits in an animal model and that it affects biochemical pathways related to learning and memory.

Effectiveness of rivastigmine on positive, negative, and cognitive symptoms of schizophrenia: a double-blind clinical trial

BACKGROUND

Several lines of evidence suggest that the cholinergic system may be disrupted in schizophrenia and so this may contribute to the cognitive impairments of schizophrenic patients. Because such deficits do not respond to neuroleptic treatment, different approaches have been done by acetylcholinesterase inhibitors (AChEIs). The objective of the present assessment was to evaluate the safety and clinical effects of rivastigmine, as an adjunctive drug, on the clinical symptoms of schizophrenia.

METHODS

A total of 46 patients with a diagnosis of schizophrenia entered into a 12-week, double-blind, clinical trial for random assignment to rivastigmine or placebo, as adjuvant to their current antipsychotic medication. Positive and Negative Symptom Scale (PANSS) and Mini Mental State Examination (MMSE) had been used as the primary outcome measures. Clinical Global Impressions- Improvement (CGI-I) Scale and Extrapyramidal Symptom Rating Scale (ESRS) had been used as the secondary measures. Treatment efficacy was evaluated by a Student's t test and repeated-measures analysis of variance (ANOVA). Statistical significance was defined as a two-sided p value ⩽ 0.05. Cohen's standard (d) and correlation measures of effect size (r) had been calculated for comparing baseline to endpoint changes.

RESULTS

According to the findings, except for significant enhancement of MMSE by rivastigmine (p < 0.001), no significant improvement in PANSS (negative symptoms), PANSS (positive symptoms), and PANSS (general psychopathology) was evident in the target group. Also, except for significant improvement of CGI-I by rivastigmine in intragroup analysis, no significant effectiveness was evident in between-group analysis or repeated-measures ANOVA. ESRS, also, did not show any significant alteration in either group. Effect size (ES) analysis showed a large improvement in MMSE by rivastigmine.

CONCLUSIONS

According to the findings, while rivastigmine could not induce significant improvement of positive and negative symptoms of schizophrenia, it caused significant enhancement of cognitive function in this group of patients.

Synthesis of fluorinated donepezil by palladium-catalyzed decarboxylative allylation of α-fluoro-β-keto ester with tri-substituted heterocyclic alkene and the self-disproportionation of its enantiomers

Catalytic asymmetric synthesis of fluorinated donepezil, a promising new therapeutic agent for Alzheimer's disease, was achieved.

Adverse Drug Reactions Reported With Cholinesterase Inhibitors

Background: No worldwide pharmacovigilance study evaluating the spectrum of adverse drug reactions (ADRs) induced by cholinesterase inhibitors (ChEI) in Alzheimer’s disease has been conducted since their emergence on the market. Objective: To describe ChEI related ADRs in Alzheimer’s disease (donepezil, rivastigmine, and galantamine) and characterize their seriousness as reported by national pharmacovigilance systems to VigiBase, a World Health Organization International Drug Monitoring Program database, between 1998 and 2013. Methods: All ChEI related reports, submitted to VigiBase between 1998 and 2013 from the five continents were extracted. Analyses were carried out for general, serious, and nonserious ADRs. Results: A total of 18 955 reports (43 753 ADRs) from 58 countries were reported: 60.1% in women; mean age 77.4 ± 9.1 years. Most reports originated from Europe (47.6%) and North America (40.4%). Rivastigmine and donepezil were involved in most reports (41.4% each). The most frequently reported ADRs were neuropsychiatric (31.4%), gastrointestinal (15.9%), general (11.9%), and cardiovascular (11.7%) disorders. During the 2006-2013 period, serious ADRs remained more often reported than nonserious ones; the most serious were neuropsychiatric (34.0%), general (14.0%), cardiovascular (12.1%), and gastrointestinal (11.6%) disorders. Medication errors were reported in 2.0% of serious cases. Death occurred in 2.3% of the reports. Conclusions: This international pharmacovigilance study highlights the ADR pattern induced by ChEIs. Neuropsychiatric events were the most frequently reported ADRs. Serious cardiovascular events were frequently reported, suggesting that their significance has probably been previously underestimated. Given the frailty of the patients and the frequent comedications, caution is advised before introducing a ChEI.

Models and mechanisms of vascular dementia

Vascular dementia (VaD) is the second leading form of dementia after Alzheimer's disease (AD) plaguing the elderly population. VaD is a progressive disease caused by reduced blood flow to the brain, and it affects cognitive abilities especially executive functioning. VaD is poorly understood and lacks suitable animal models, which constrain the progress on understanding the basis of the disease and developing treatments. This review article discusses VaD, its risk factors, induced cognitive disability, various animal (rodent) models of VaD, pathology, and mechanisms of VaD and treatment options.

Anti-inflammatory, antioxidant and anti-acetylcholinesterase activities of Bouvardia ternifolia: potential implications in Alzheimer's disease

Bouvardia ternifolia has been used medicinally to treat inflammation. In the present study, we investigate the anti-Alzheimer's potential effect of the hydroalcoholic extract of B. ternifolia through evaluation of anti-inflammatory and antioxidant activities, quantification of the percentage inhibition of acetylcholinesterase activity, protection effect against β-amyloid fibrillar-induce neurotoxicity, and the identification of the main constituents. Our results show that B. ternifolia extract and ethyl acetate fraction induced anti-inflammatory effects by reducing inflammation by >70 %, while antioxidant test revealed significant IC50 values for flavonoid content fraction (30.67 ± 2.09 μg/ml) and ethyl acetate fraction (42.66 ± 0.93 μg/ml). The maximum inhibition of acetylcholinesterase was exhibited by scopoletin content fraction (38.43 ± 3.94 %), while ethyl acetate fraction exerted neuroprotective effect against β-amyloid peptide (83.97 ± 5.03 %). Phytochemical analysis, showed the presence of 3-O-quercetin glucopyranoside (415 mg/g), rutin (229.9 mg/g), ursolic and oleanolic acid (54 and 20.8 mg/g respectively), 3-O-quercetin rhamnopyranoside (12.8 mg/g), chlorogenic acid (9.5 mg/g), and scopoletin (1.38 mg/g). Our findings support the use of B. ternifolia since the extract induced significant neuroprotection against β-amyloid peptide, anti-inflammatory, antioxidant and anti-acetylcholinesterase effects that could be attributed to its contents of polyphenols, coumarins, and triterpenes, and encourage further studies for development of this extract as therapeutic agent in treatment of Alzheimer's disease.

Syncope secondary to second-degree atrioventricular block with donepezil use

Donepezil, an acetylcholinesterase inhibitor, is approved for the treatment of mild to moderate dementia secondary to Alzheimer's disease. Although most prescribers are aware of the common gastrointestinal side effects of donepezil, cardiovascular side effects are rarely observed. Cardiovascular side effects of donepezil have almost always been observed in patients with a history of conduction defects or sick sinus syndrome. We report a case of a woman with early onset Alzheimer's disease and no history of cardiac disease who developed second-degree heart block after a few weeks of therapy with donepezil. Withdrawal of donepezil led to resolution of the atrioventricular block.

Encephalopathy from unintentional donepezil and memantine ingestion

Donepezil and memantine are commonly prescribed antidementia drugs. There is a paucity of literature concerning pediatric ingestions of these drugs. We describe a case of a 2-year-old child who developed encephalopathy after an unintentional ingestion of donepezil and memantine. A 2-year-old girl was found by her family members agitated and reporting visual hallucinations. In the emergency department, she became sedated and had rightward eye deviation. She was hospitalized and had extensive neurological and infectious disease testing that was unremarkable, except for an electroencephalogram, which showed a nonspecific encephalopathy. She recovered with supportive care for 72 hours. Serum concentrations of donepezil and memantine measured on arrival were 470 ng/mL (therapeutic range, 25-50 ng/mL) and 32 ng/mL (therapeutic range, 70-150 ng/mL), respectively. This case demonstrates that unintentional ingestions of memantine and donepezil can potentially cause significant and prolonged neurological symptoms in pediatric patients.

Donepezil, an acetylcholinesterase inhibitor, attenuates nicotine self-administration and reinstatement of nicotine seeking in rats

Nicotine craving and cognitive impairments represent core symptoms of nicotine withdrawal and predict relapse in abstinent smokers. Current smoking cessation pharmacotherapies have limited efficacy in preventing relapse and maintaining abstinence during withdrawal. Donepezil is an acetylcholinesterase inhibitor that has been shown previously to improve cognition in healthy non-treatment-seeking smokers. However, there are no studies examining the effects of donepezil on nicotine self-administration and/or the reinstatement of nicotine-seeking behavior in rodents. The present experiments were designed to determine the effects of acute donepezil administration on nicotine taking and the reinstatement of nicotine-seeking behavior, an animal model of relapse in abstinent human smokers. Moreover, the effects of acute donepezil administration on sucrose self-administration and sucrose seeking were also investigated in order to determine whether donepezil's effects generalized to other reinforced behaviors. Acute donepezil administration (1.0 or 3.0 mg/kg, i.p.) attenuated nicotine, but not sucrose self-administration maintained on a fixed-ratio 5 schedule of reinforcement. Donepezil administration also dose-dependently attenuated the reinstatement of both nicotine- and sucrose-seeking behaviors. Commonly reported adverse effects of donepezil treatment in humans are nausea and vomiting. However, at doses required to attenuate nicotine self-administration in rodents, no effects of donepezil on nausea/malaise as measured by pica were observed. Collectively, these results indicate that increased extracellular acetylcholine levels are sufficient to attenuate nicotine taking and seeking in rats and that these effects are not due to adverse malaise symptoms such as nausea.

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.

Role of donepezil in autism: its conduciveness in psychopharmacotherapy

A woman consulted psychiatric Out-Patient Department (OPD) for her 5-year and 2-month-old son presenting with typical autistic symptoms like social, behavioural, and communicational ineptitudeness. Subsequent treatment with Donepezil resulted in marked improvement in the aforementioned symptomatology. Recent studies in autistic child have shown diminished acetylcholine and nicotinic receptor activity, thus an acetylcholinergic enhancer, Donepezil, likely accounts for improvement in autistic symptoms. Evidently, the case report consolidates Donepezil role as a potentially useful agent in the treatment of cognitive and behavioural symptoms observed in this disorder.

Seizures and epilepsy in Alzheimer's disease

Many studies have shown that patients with Alzheimer's disease (AD) are at increased risk for developing seizures and epilepsy. However, reported prevalence and incidence of seizures and relationship of seizures to disease measures such as severity, outcome, and progression vary widely between studies. We performed a literature review of the available clinical and epidemiological data on the topic of seizures in patients with AD. We review seizure rates and types, risk factors for seizures, electroencephalogram (EEG) studies, and treatment responses. Finally, we consider limitations and methodological issues. There is considerable variability in the reported prevalence and incidence of seizures in patients with AD-with reported lifetime prevalence rates of 1.5-64%. More recent, prospective, and larger studies in general report lower rates. Some, but not all, studies have noted increased seizure risk with increasing dementia severity or with younger age of AD onset. Generalized convulsive seizures are the most commonly reported type, but often historical information is the only basis used to determine seizure type and the manifestation of seizures may be difficult to distinguish from other behaviors common in demented patients. EEG has infrequently been performed and reported. Data on treatment of seizures in AD are extremely limited. Similarly, the relationship between seizures and cognitive impairment in AD is unclear. We conclude that the literature on seizures and epilepsy in AD, including diagnosis, risk factors, and response to treatment suffers from methodological limitations and gaps.

Nantenine as an acetylcholinesterase inhibitor: SAR, enzyme kinetics and molecular modeling investigations

Nantenine, as well as a number of flexible analogs, were evaluated for acetylcholinesterase (AChE) inhibitory activity in microplate spectrophotometric assays based on Ellman's method. It was found that the rigid aporphine core of nantenine is an important structural requirement for its anticholinesterase activity. Nantenine showed mixed inhibition kinetics in enzyme assays. Molecular docking experiments suggest that nantenine binds preferentially to the catalytic site of AChE but is also capable of interacting with the peripheral anionic site (PAS) of the enzyme, thus accounting for its mixed inhibition profile. The aporphine core of nantenine may thus be a useful template for the design of novel PAS or dual-site AChE inhibitors. Inhibiting the PAS is desirable for prevention of aggregation of the amyloid peptide Aβ, a major causative factor in the progression of Alzheimer's disease (AD).

Histological protection by donepezil against neurodegeneration induced by ischemia-reperfusion in the rat retina

Although a blockade of acetylcholine esterase has been reported to suppress neuronal cell death induced by exogenous glutamate and beta-amyloid, information is still limited regarding the neuroprotective effects of the acetylcholine esterase inhibitor donepezil. We histologically examined the effects of donepezil on neuronal injury induced by ischemia-reperfusion. Intravenous and intravitreous treatment with donepezil 15 min prior to ischemia dramatically reduced the retinal damage. The protective effect of donepezil in the ganglion cell layer was not affected by mecamylamine, a nicotinic acetylcholine-receptor antagonist, nor scopolamine, a muscarinic acetylcholine-receptor antagonist. The protective effect of donepezil in the inner plexiform layer was reduced not by mecamylamine, but by scopolamine. Neostigmine, a choline-esterase inhibitor, and pilocarpine, a muscarinic acetylcholine-receptor agonist, have protective effects in the inner plexiform layer and the inner nuclear layer. These results suggest that not only the activation of acetylcholine receptors but also a mechanism unrelated to acetylcholine-esterase inhibition contribute to the protective effect of donepezil on the ganglion cells in the ischemic-reperfused rat retina. Donepezil may be useful as a therapeutic drug against retinal diseases that cause neuronal cell death such as glaucoma with high intraocular pressure.

Treatment options in Alzheimer's disease: maximizing benefit, managing expectations

Alzheimer's disease (AD) is becoming an increasingly heavy burden on the society of developed countries, and physicians now face the challenge of providing efficient treatment regimens to an ever-higher number of individuals affected by the disease. Currently approved anti-AD therapies - the cholinesterase inhibitors and the N-methyl-D-aspartate receptor antagonist memantine - offer modest symptomatic relief, which can be enhanced using combination therapy with both classes of drugs. Additionally, alternative therapies such as nonsteroidal anti-inflammatory drugs, vitamin E, selegiline, Ginkgo biloba extracts, estrogens, and statins, as well as behavioral and lifestyle changes, have been explored as therapeutic options. Until a therapy is developed that can prevent or reverse the disease, the optimal goal for effective AD management is to develop a treatment regimen that will yield maximum benefits for individual patients across multiple domains, including cognition, daily functioning, and behavior, and to provide realistic expectations for patients and caregivers throughout the course of the disease. This review provides a basic overview of approved AD therapies, discusses some pharmacologic and nonpharmacologic treatment strategies that are currently being investigated, and offers suggestions for optimizing treatment to fit the needs of individual patients.

Donepezil improves obstructive sleep apnea in Alzheimer disease: a double-blind, placebo-controlled study

BACKGROUND

There is an association between Alzheimer disease and sleep-disordered breathing. Donepezil is the drug most frequently used to treat cognitive symptoms in Alzheimer disease. This study evaluates the effects of donepezil on obstructive sleep apnea in patients with Alzheimer disease.

METHODS

Randomized, double-blind, placebo-controlled design. Twenty-three patients with mild-to-moderate Alzheimer disease and apnea-hypopnea index (AHI) > 5/h were allocated to two groups: donepezil treated (n = 11) and placebo treated (n = 12). Polysomnography and cognitive evaluation using Alzheimer disease assessment scale-cognitive (ADAS-cog) subscale were performed at baseline and after 3 months. Cognitive and sleep data were analyzed using analysis of variance.

RESULTS

AHI and oxygen saturation improved significantly after donepezil treatment compared to baseline and placebo (p < 0.05). Rapid eye movement (REM) sleep duration increased after donepezil treatment (p < 0.05). ADAS-cog scores improved after donepezil treatment, although they did not correlate with REM sleep increase and sleep apnea improvement (p < 0.01).

CONCLUSIONS

Donepezil treatment improved AHI and oxygen saturation in patients with Alzheimer disease. Treatment also increased REM sleep duration and reduced ADAS-cog scores.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00480870.

Functional outcomes of drug treatment in Alzheimer's disease: A systematic review and meta-analysis

BACKGROUND

Patient functioning is an important outcome in Alzheimer's disease, but treatment-related improvements in patient function are difficult to quantify because a number of different scales are used in its measurement.

OBJECTIVE

To evaluate systematically the evidence relating to patient functioning as an outcome measure in the drug treatment of Alzheimer's disease. Data were obtained by searching MEDLINE, EMBASE, The Cochrane Library and the International Pharmaceutical Abstracts from 1980 through to December 2005 for studies assessing functional outcomes with donepezil, galantamine, rivastigmine and memantine in Alzheimer's disease. Reference lists were searched manually and pharmaceutical manufacturers were invited to submit dossiers. Trained reviewers abstracted data and assessed the internal validity (quality) of trials using predefined criteria. Standardised effect sizes (i.e. Cohen's standardised mean difference [d]) for various functional outcome scales and pooled mean incidence and 95% CIs for adverse events were calculated and summarised qualitatively and quantitatively. Meta regression was used to explore potential heterogeneity.

RESULTS

Overall, the standardised effect size for functional outcome measures was small (d = 0.1-0.4) among included studies. However, effect sizes consistently favoured drug treatment over placebo. For all drugs, pooled standardised effect sizes were consistent in both short (<24 weeks; d = 0.25; 95% CI 0.13, 0.37) and long trials (>or=24 weeks; d = 0.29; 95% CI 0.22, 0.36). The pooled effect size was not significantly affected by parameters such as disease severity, age, gender and drug dose. Adverse events were generally limited to gastrointestinal problems, weight loss and dizziness, all of which were reported in <20% of patients on average.

CONCLUSIONS

Standardised estimates of effect size across diverse functional outcome measures for drug treatment in patients with Alzheimer's disease were small and the data reflect only a modest trend favouring active treatment over placebo. However, given the current lack of other effective treatments for Alzheimer's disease, this trend supports the clinical benefits of these treatments with regard to this important health outcome.

Complete atrioventricular block and ventricular tachyarrhythmia associated with donepezil

Donepezil is a reversible inhibitor of acetylcholinesterase. Its commonest adverse events are nausea, diarrhoea, malaise, dizziness, and insomnia. Symptomatic cardiac rhythm disturbances associated with the use of donepezil are extremely unusual. An 82 year old patient with Alzheimer's disease (AD) developed complete atrioventricular block and ventricular tachyarrhythmia 1 month after starting treatment with donepezil, and was admitted to the emergency department because of dizziness and syncope. Immediately after admission, a temporary ventricular pacing catheter was placed in the right ventricle. Rhythm was observed to return to a normal sinus rhythm on the fourth day after implantation. Treatment of AD with cholinesterase inhibitors carries a risk of cardiac disturbances. In addition to sinusal bradycardia, it may lead to such major dysrhythmias as complete atrioventricular block and ventricular tachyarrhythmia, as in our case. In this report, we describe symptomatic complete atrioventricular block and ventricular tachyarrhythmia associated with the use of donepezil.

The significance of the cholinergic system in the brain during aging and in Alzheimer's disease

Acetylcholine is widely distributed in the nervous system and has been implicated to play a critical role in cerebral cortical development, cortical activity, controlling cerebral blood flow and sleep-wake cycle as well as in modulating cognitive performances and learning and memory processes. Cholinergic neurons of the basal forebrain complex have been described to undergo moderate degenerative changes during aging, resulting in cholinergic hypofunction that has been related to the progressing memory deficits with aging. Basal forebrain cholinergic cell loss is also a consistent feature of Alzheimer's disease, which has been suggested to cause, at least partly, the cognitive deficits observed, and has led to the formulation of the cholinergic hypotheses of geriatric memory dysfunction. Impaired cortical cholinergic neurotransmission may also contribute to beta-amyloid plaque pathology and increase phosphorylation of tau protein the main component of neurofibrillar tangles in Alzheimer's disease. Understanding the molecular mechanisms underlying the interrelationship between cortical cholinergic dysfunction, beta-amyloid formation and deposition, and tau pathology in Alzheimer's disease, would allow to derive potential treatment strategies to pharmacologically intervene in the disease-causing signaling cascade.

Circadian cholinergic rhythms: implications for cholinesterase inhibitor therapy

Therapies for Alzheimer's disease (AD) at present augment the deteriorating cholinergic system, are reasonably well tolerated, and are convenient, given once or twice a day. They may, however, support or oppose endogenous circadian cholinergic rhythms. Drugs with a duration of action longer than a day are at odds with the physiology of the cholinergic system, which is active during the day and quiescent at night. Sleep and the consolidation of daytime experience into memory may be disturbed. Tolerance commonly develops, substantial counterregulatory increases in acetylcholinesterase (AChE) have been measured, and brain AChE inhibition is lower than predicted. Therefore, the duration of action and timing of administration, as they relate to natural cholinergic rhythms, are factors to be considered in optimizing cholinergic AD therapeutics.

Protective effect of donepezil on retinal ganglion cells in vitro and in vivo

The neuroprotective effect of donepezil, an acetylcholinesterase inhibitor on retinal ganglion cells (RGCs), was examined. The survival of purified RGCs after exposure to glutamate with or without donepezil (10(- 7) M to 10(- 5) M) was measured after 3 days in culture. In vivo, the neuroprotective effect of donepezil was examined by quantifying the number of viable RGCs 7 days after axotomy in adult rats. In vitro, donepezil dose-dependently reduced RGC death caused by glutamate toxicity. Oral administration of donepezil (10 mg kg(-1) day(-1)) significantly reduced RGC death after axotomy. In conclusion, donepezil exerts a protective effect on RGCs both in vitro and in vivo.