Variability of AChE, BChE, and ChAT genes in the late-onset form of Alzheimer's disease and relationships with response to treatment with Donepezil and Rivastigmine

Comparative in silico analysis of CNS-active molecules targeting the blood-brain barrier choline transporter for Alzheimer's disease therapy

This study investigated the blood‒brain barrier (BBB) permeability of the central nervous system (CNS)-active compounds donepezil (DON), methionine (MET), and memantine (MEM) by employing a comprehensive in silico approach. These compounds are of particular interest for Alzheimer's disease (AD) therapy. Rigid-flexible molecular docking simulations indicated favorable binding affinities of all the compounds with BBB-ChT, with DON exhibiting the highest binding affinity (ΔGbind = -10.26 kcal/mol), predominantly mediated by significant hydrophobic interactions. In silico kinetic profiling suggested the stability of the DON/BBB-ChT complex, with ligand release prompted by conformational changes. 3D molecular alignment corroborated a minor conformational shift for DON in its minimal binding energy pose. Predictions indicated that active transport mechanisms notably enhance the brain distribution of donepezil compared to that of MET and MEM. Additionally, DON and MEM exhibited low mutagenic probabilities, while MET was identified as highly mutagenic. Overall, these findings highlight the potential of donepezil for superior BBB penetration, primarily through active transport mechanisms, underscoring the need for further validation through in vitro and in vivo studies for effective AD treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00245-w.

Association of CHAT Gene Polymorphism rs3793790 and rs2177370 with Donepezil Response and the Risk of Alzheimer's Disease Continuum

Background

Genetic variation plays an important role in drug response, there are few relevant studies on patients with Alzheimer's disease continuum (ADC).

Objective

This study focused on the associations between two single nucleotide polymorphisms (SNPs) (rs3793790 and rs2177370) located in the CHAT gene and donepezil response in ADC patients, and further evaluated the associations between the two SNPs and ADC.

Material and Methods

According to 2018 National Institute on Aging and Alzheimer's Association (NIA-AA) standard, amyloid β-protein positive (Aβ+) and negative (Aβ-) patients were recruited according to the Aβ-PET/CT standard. rs3793790 and rs2177370 were genotyped in buccal swab samples by using the MassARRAY system. We used the Mini Mental State Examination (MMSE) in Chinese version, caregiver evaluation, and prescribing behavior to assess therapeutic response during the 9-month period. Using logistic regression models, we analyzed the relationship between the two SNPs and donepezil response in 58 Aβ+ patients treated with donepezil alone at the initial diagnosis of ADC. We also explored a probable link between the two SNPs and ADC in 147 Aβ+ and 73 Aβ- patients using a logistic regression analysis.

Results

The chance of donepezil response was higher in patients with the G allele of rs3793790 and/or the A allele of rs2177370 than in those without (odds ratio (OR) 6.83, 95% confidence interval (CI): 1.64-28.49). Additionally, the rs3793790 variant was not associated with ADC, whereas the A allele in rs2177370 increased 1.51-fold the ADC risk (OR 2.51, 95% CI: 1.28-4.95).

Conclusion

The genetic variants of rs3793790 and rs2177370 were associated with the donepezil response, and rs2177370 may have a moderate relationship with the risk of ADC.

Pharmacogenomics of Dementia: Personalizing the Treatment of Cognitive and Neuropsychiatric Symptoms

Dementia is a syndrome of global and progressive deterioration of cognitive skills, especially memory, learning, abstract thinking, and orientation, usually affecting the elderly. The most common forms are Alzheimer's disease, vascular dementia, and other (frontotemporal, Lewy body disease) dementias. The etiology of these multifactorial disorders involves complex interactions of various environmental and (epi)genetic factors and requires multiple forms of pharmacological intervention, including anti-dementia drugs for cognitive impairment, antidepressants, antipsychotics, anxiolytics and sedatives for behavioral and psychological symptoms of dementia, and other drugs for comorbid disorders. The pharmacotherapy of dementia patients has been characterized by a significant interindividual variability in drug response and the development of adverse drug effects. The therapeutic response to currently available drugs is partially effective in only some individuals, with side effects, drug interactions, intolerance, and non-compliance occurring in the majority of dementia patients. Therefore, understanding the genetic basis of a patient's response to pharmacotherapy might help clinicians select the most effective treatment for dementia while minimizing the likelihood of adverse reactions and drug interactions. Recent advances in pharmacogenomics may contribute to the individualization and optimization of dementia pharmacotherapy by increasing its efficacy and safety via a prediction of clinical outcomes. Thus, it can significantly improve the quality of life in dementia patients.

Influence of the chronic groundwater fluoride consumption on cholinergic enzymes, ACHE and BCHE gene SNPs and pro-inflammatory cytokines: A study with Pakistani population groups

Fluoride is one of the abundant elements found in the Earth's crust and is a global environmental issue. The present work aimed to find the impact of chronic consumption of fluoride contained groundwater on human subjects. Five hundred and twelve volunteers from different areas of Pakistan were recruited. Cholinergic status, acetylcholinesterase and butyrylcholinesterase gene SNPs and pro-inflammatory cytokines were examined. Association analysis, regression and other standard statistical analyses were performed. Physical examination of the fluoride endemic areas' participants revealed the symptoms of dental and skeletal fluorosis. Cholinergic enzymes (AChE and BChE) were significantly increased among different exposure groups. ACHE gene 3'-UTR variant and BCHE K-variant showed a significant association with risk of fluorosis. Pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) were found to be increased and have a significant correlation in response to fluoride exposure and cholinergic enzymes. The study concludes that chronic consumption of high fluoride-contained water is a risk factor for developing low-grade systemic inflammation through the cholinergic pathway and the studied cholinergic gene SNPs were identified to be associated with the risk of flurosis.

Determinants of approved acetylcholinesterase inhibitor response outcomes in Alzheimer's disease: relevance for precision medicine in neurodegenerative diseases

Acetylcholinesterase inhibitors (ChEI) are the global standard of care for the symptomatic treatment of Alzheimer's disease (AD) and show significant positive effects in neurodegenerative diseases with cognitive and behavioral symptoms. Although experimental and large-scale clinical evidence indicates the potential long-term efficacy of ChEI, primary outcomes are generally heterogeneous across outpatient clinics and regional healthcare systems. Sub-optimal dosing or slow tapering, heterogeneous guidelines about the timing for therapy initiation (prodromal versus dementia stages), healthcare providers' ambivalence to treatment, lack of disease awareness, delayed medical consultation, prescription of ChEI in non-AD cognitive disorders, contribute to the negative outcomes. We present an evidence-based overview of determinants, spanning genetic, molecular, and large-scale networks, involved in the response to ChEI in patients with AD and other neurodegenerative diseases. A comprehensive understanding of cerebral and retinal cholinergic system dysfunctions along with ChEI response predictors in AD is crucial since disease-modifying therapies will frequently be prescribed in combination with ChEI. Therapeutic algorithms tailored to genetic, biological, clinical (endo)phenotypes, and disease stages will help leverage inter-drug synergy and attain optimal combined response outcomes, in line with the precision medicine model.

Predictors of response to acetylcholinesterase inhibitors in dementia: A systematic review

Background

The mainstay of therapy for many neurodegenerative dementias still relies on acetylcholinesterase inhibitors (AChEI); however, there is debate on various aspects of such treatment. A huge body of literature exists on possible predictors of response, but a comprehensive review is lacking. Therefore, our aim is to perform a systematic review of the predictors of response to AChEI in neurodegenerative dementias, providing a categorization and interpretation of the results.

Methods

We conducted a systematic review of the literature up to December 31st, 2021, searching five different databases and registers, including studies on rivastigmine, donepezil, and galantamine, with clearly defined criteria for the diagnosis of dementia and the response to AChEI therapy. Records were identified through the string: predict * AND respon * AND (acetylcholinesterase inhibitors OR donepezil OR rivastigmine OR galantamine). The results were presented narratively.

Results

We identified 1,994 records in five different databases; after exclusion of duplicates, title and abstract screening, and full-text retrieval, 122 studies were finally included.

Discussion

The studies show high heterogeneity in duration, response definition, drug dosage, and diagnostic criteria. Response to AChEI seems associated with correlates of cholinergic deficit (hallucinations, fluctuating cognition, substantia innominate atrophy) and preserved cholinergic neurons (faster alpha on REM sleep EEG, increased anterior frontal and parietal lobe perfusion after donepezil); white matter hyperintensities in the cholinergic pathways have shown inconsistent results. The K-variant of butyrylcholinesterase may correlate with better response in late stages of disease, while the role of polymorphisms in other genes involved in the cholinergic system is controversial. Factors related to drug availability may influence response; in particular, low serum albumin (for donepezil), CYP2D6 variants associated with reduced enzymatic activity and higher drug doses are the most consistent predictors, while AChEI concentration influence on clinical outcomes is debatable. Other predictors of response include faster disease progression, lower serum cholesterol, preserved medial temporal lobes, apathy, absence of concomitant diseases, and absence of antipsychotics. Short-term response may predict subsequent cognitive response, while higher education might correlate with short-term good response (months), and long-term poor response (years). Age, gender, baseline cognitive and functional levels, and APOE relationship with treatment outcome is controversial.

Articulating target-mining techniques to disinter Alzheimer's specific targets for drug repurposing

BACKGROUND AND OBJECTIVES

Alzheimer's Disease (AD), an extremely progressive neurodegenerative disorder is an amalgamation of numerous intricate pathological networks. This century old disease is still an unmet medical condition owing to the modest efficacy of existing therapeutic agents in antagonizing the multi-targeted pathological pathways underlying AD. Given the paucity in AD specific drugs, fabricating comprehensive research strategies to envision disease specific targets to channelize and expedite drug discovery are mandated. However, the dwindling approval rates and stringent regulatory constraints concerning the approval of a new chemical entity is daunting the pharmaceutical industries from effectuating de novo research. To bridge the existing gaps in AD drug research, a promising contemporary way out could be drug repurposing. This drug repurposing investigation is intended to envisage AD specific targets and create drug libraries pertinent to the shortlisted targets via a series of avant-garde bioinformatics and computational strategies.

METHODS

Transcriptomic analysis of three AD specific datasets viz., GSE122063, GSE15222 and GSE5281 revealed significant Differentially Expressed Genes (DEGs) and subsequent Protein-Protein Interactions (PPI) network analysis captured crucial AD targets. Later, homology model was constructed through I-TASSER for a shortlisted target protein which lacked X-ray crystallographic structure and the built protein model was validated by molecular dynamic simulations. Further, drug library was created for the shortlisted target based on structural and side effect similarity with respective standard drugs. Finally, molecular docking, binding energy calculations and molecular dynamics studies were carried out to unravel the interactions exhibited by drugs from the created library with amino acids in active binding pocket of RGS4.

RESULTS

SST and RGS4 were shortlisted as potentially significant AD specific targets, however, the less explored target RGS4 was considered for further sequential analysis. Homology model constructed for RGS4 displayed best quality when validated through Ramachandran plot and ERRAT plot. Subsequent docking and molecular dynamics studies showcased substantial affinity demonstrated by three drugs viz., Ziprasidone, Melfoquine and Metaxalone from the created drug libraries, towards RGS4.

CONCLUSION

This virtual analysis forecasted the repurposable potential of Ziprasidone, Melfoquine and Metaxalone against AD based on their affinity towards RGS4, a key AD-specific target.

Pharmacogenetics of Donepezil and Memantine in Healthy Subjects

Donepezil and memantine are the most common drugs used for Alzheimer's disease. Their low effectiveness could partly be explained by genetic factors. Thus, we aim to identify Single Nucleotide Polymorphisms (SNPs) associated with pharmacokinetics, pharmacodynamics, and the safety of donepezil and memantine. For this regard, 25 volunteers enrolled in a bioequivalence clinical trial were genotyped for 67 SNPs in 21 genes with a ThermoFisher QuantStudio 12K Flex OpenArray. The statistical strategy included a univariate analysis that analyzed the association of these SNPs with pharmacokinetic parameters or the development of adverse drug reactions (ADRs) followed by a Bonferroni-corrected multivariate regression. Statistical analyses were performed with SPSS software v.21 and R commander (version v3.6.3). In the univariate analysis, fourteen and sixteen SNPs showed a significant association with memantine's and donepezil's pharmacokinetic parameters, respectively. Rs20417 (PTGS2) was associated with the development of at least one ADR. However, none of these associations reached the significance threshold in the Bonferroni-corrected multivariate analysis. In conclusion, we did not observe any significant association of the SNPs analyzed with memantine and donepezil pharmacokinetics or ADRs. Current evidence on memantine and donepezil pharmacogenetics does not justify their inclusion in pharmacogenetic guidelines.

Pharmacogenetic studies in Alzheimer disease

INTRODUCTION

Alzheimer disease (AD) is the most common cause of dementia and is considered one of the main causes of disability and dependence affecting quality of life in elderly people and their families. Current pharmacological treatment includes acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine) and memantine; however, only one-third of patients respond to treatment. Genetic factors have been shown to play a role in this inter-individual variability in drug response.

DEVELOPMENT

We review pharmacogenetic reports of AD-modifying drugs, the pharmacogenetic biomarkers included, and the phenotypes evaluated. We also discuss relevant methodological considerations for the design of pharmacogenetic studies into AD. A total of 33 pharmacogenetic reports were found; the majority of these focused on the variability in response to and metabolism of donepezil. Most of the patients included were from Caucasian populations, although some studies also include Korean, Indian, and Brazilian patients. CYP2D6 and APOE are the most frequently studied biomarkers. The associations proposed are controversial.

CONCLUSIONS

Potential pharmacogenetic biomarkers for AD have been identified; however, it is still necessary to conduct further research into other populations and to identify new biomarkers. This information could assist in predicting patient response to these drugs and contribute to better treatment decision-making in a context as complex as aging.

Revelation of Pivotal Genes Pertinent to Alzheimer's Pathogenesis: A Methodical Evaluation of 32 GEO Datasets

Alzheimer’s disease (AD), a dreadful neurodegenerative disorder that affects cognitive and behavioral function in geriatric populations, is characterized by the presence of amyloid deposits and neurofibrillary tangles in brain regions. The International D World Alzheimer Report2018 noted a global prevalence of 50 million AD cases and forecasted a threefold rise to 139 million by 2050. Although there exist numerous genetic association studies pertinent to AD in different ethnicities, critical genetic factors and signaling pathways underlying its pathogenesis remain ambiguous. This study was aimed to analyze the genetic data retrieved from 32 Gene Expression Omnibus datasets belonging to diverse ethnic cohorts in order to identify overlapping differentially expressed genes (DEGs). Stringent selection criteria were framed to shortlist appropriate datasets based on false discovery rate (FDR) p-value and log FC, and relevant details of upregulated and downregulated DEGs were retrieved. Among the 32 datasets, only six satisfied the selection criteria. The GEO2R tool was employed to retrieve significant DEGs. Nine common DEGs, i.e., SLC5A3, BDNF, SST, SERPINA3, RTN3, RGS4, NPTX, ENC1 and CRYM were found in more than 60% of the selected datasets. These DEGs were later subjected to protein–protein interaction analysis with 18 AD-specific literature-derived genes. Among the nine common DEGs, BDNF, SST, SERPINA3, RTN3 and RGS4 exhibited significant interactions with crucial proteins including BACE1, GRIN2B, APP, APOE, COMT, PSEN1, INS, NEP and MAPT. Functional enrichment analysis revealed involvement of these genes in trans-synaptic signaling, chemical transmission, PI3K pathway signaling, receptor–ligand activity and G protein signaling. These processes are interlinked with AD pathways.

Genetic Variants and Oxidative Stress in Alzheimer's Disease

In an aging society, the number of people suffering from Alzheimer's Disease (AD) is still growing. Currently, intensive research is being carried out on the pathogenesis of AD. The results of these studies indicated that oxidative stress plays an important role in the onset and development of this disease. Moreover, in AD oxidative stress is generated by both genetic and biochemical factors as well as the functioning of the systems responsible for their formation and removal. The genetic factors associated with the regulation of the redox system include TOMM40, APOE, LPR, MAPT, APP, PSEN1 and PSEN2 genes. The most important biochemical parameters related to the formation of oxidative species in AD are p53, Homocysteine (Hcy) and a number of others. The formation of Reactive Oxygen Species (ROS) is also related to the efficiency of the DNA repair system, the effectiveness of the apoptosis, autophagy and mitophagy processes as well as the antioxidant potential. However, these factors are responsible for the development of many disorders, often with similar clinical symptoms, especially in the early stages of the disease. The discovery of markers of the early diagnosis of AD may contribute to the introduction of pharmacotherapy and slow down the progression of this disease.

Genetic Differences in Dorsal Hippocampus Acetylcholinesterase Activity Predict Contextual Fear Learning Across Inbred Mouse Strains

Learning is a critical behavioral process that is influenced by many neurobiological systems. We and others have reported that acetylcholinergic signaling plays a vital role in learning capabilities, and it is especially important for contextual fear learning. Since cholinergic signaling is affected by genetic background, we examined the genetic relationship between activity levels of acetylcholinesterase (AChE), the primary enzyme involved in the acetylcholine metabolism, and learning using a panel of 20 inbred mouse strains. We measured conditioned fear behavior and AChE activity in the dorsal hippocampus, ventral hippocampus, and cerebellum. Acetylcholinesterase activity varied among inbred mouse strains in all three brain regions, and there were significant inter-strain differences in contextual and cued fear conditioning. There was an inverse correlation between fear conditioning outcomes and AChE levels in the dorsal hippocampus. In contrast, the ventral hippocampus and cerebellum AChE levels were not correlated with fear conditioning outcomes. These findings strengthen the link between acetylcholine activity in the dorsal hippocampus and learning, and they also support the premise that the dorsal hippocampus and ventral hippocampus are functionally discrete.

Gene Polymorphisms Affecting the Pharmacokinetics and Pharmacodynamics of Donepezil Efficacy

Donepezil (DNP) is the first-line drug used for Alzheimer's disease (AD). However, the therapeutic response rate of patients to DNP varies from 20 to 60%. The main reason for the large differences in the clinical efficacy of DNP therapy is genetic factors, some of which affect pharmacokinetics (PK), while others affect pharmacodynamics (PD). Thus, much emphasis has been placed on the investigation of an association between PK- and PD-related gene polymorphisms and therapeutic response to DNP, but a consistent view does not yet exist. In this review, we summarize recent findings regarding genetic factors influencing the clinical efficacy of DNP, including substantial differences in individual responses as a consequence of polymorphisms in Cytochrome P450 (CYP) 2D6, CY3A4, CY3A5, APOE, ABCA1, ABCB1, ESR1, BCHE, PON-1, CHRNA7, and CHAT. We also discuss possible strategies for the evaluation of the clinical efficacy of DNP, with a specific focus on possible biomarkers of PK/PD parameters, and provide perspectives and limitations within the field, which will also be beneficial for understanding the multiple mechanisms of DNP therapy in AD.

Butyrylcholinesterase Protein Ends in the Pathogenesis of Alzheimer's Disease-Could BCHE Genotyping Be Helpful in Alzheimer's Therapy?

Late-onset Alzheimer’s disease (AD) is clinically characterized by a progressive decline of memory and other cognitive functions leading to the loss of the ability to perform everyday activities. Only a few drugs have been approved to treat AD dementia over the past century since the first AD patient was diagnosed. Drugs increasing the availability of neurotransmitters at synapses in the brain are used clinically in the treatment of AD dementia, and cholinesterase inhibitors (ChEIs) are the mainstay of the therapy. A detrimental effect on cognitive function has been reported in patients with pharmacological inhibition of acetylcholinesterase (AChE) by ChEIs and reduced butyrylcholinesterase (BChE) activity due to the single nucleotide polymorphisms. The BChE K-variant (rs1803274), the most common genetic variant of the BCHE gene, was thought to reduce enzyme activity reflecting the lower clinical response to rivastigmine in AD patients. During ChEIs therapy, patients carrying reduced-activity BChE do not present such improved attention like patients with the wild-type enzyme. On the other hand, alterations in the BCHE gene causing enzyme activity reduction may delay AD onset in patients at risk by preserving the level of cortical acetylcholine (ACh). Based on our previous results, we conclude that SNPs localized outside of the coding sequence, in 5’UTR (rs1126680) and/or intron 2 (rs55781031) of the BCHE gene, but not solely K-variant alteration (p.A539T) itself, are responsible for reduced enzyme activity. Therefore, we suspect that not BChE-K itself, but these coexisting SNPs (rs1126680 and rs55781031), could be associated with deleterious changes in cognitive decline in patients treated with ChEIs. Based on the results, we suggest that SNPs (rs1126680) and/or (rs55781031) genotyping should be performed to identify subjects at risk for lowered efficacy ChEIs therapy, and such patients should be treated with a lower rivastigmine dosage. Finally, our sequence analysis of the N-terminal end of N-BChE revealed evolutionarily conserved amino acid residues that can be involved in disulfide bond formation and anchoring of N-BChE in the cell membrane.

Effect of genetic polymorphisms on Alzheimer's disease treatment outcomes: an update

Genetic variations in individuals may cause differences in the response to cholinesterase inhibitor drugs used in the treatment of Alzheimer's disease (AD). Through this review, we aimed to understand the potential relationship between genetic polymorphisms and treatment response in AD. We conducted a systematic review of the studies published from 2006 to 2018 that assessed the relationship between genetic polymorphisms and the pharmacotherapeutic outcomes of patients with AD. Via several possible mechanisms, genetic polymorphisms of many genes, including ABCA1, ApoE3, CYP2D6, CHAT, CHRNA7, and ESR1, appear to have strong correlations with the treatment response of patients with AD. Indeed, these genetic polymorphisms, either in the form of single nucleotide polymorphisms or direct changes to one or more amino acids, have been shown to cause differences in the therapeutic response. In summary, our findings indicate that genetic polymorphisms should be considered in the management of AD to achieve both effective and efficient treatment outcomes in terms of cost and prognosis.

Deleterious Effect of Butyrylcholinesterase K-Variant in Donepezil Treatment of Mild Cognitive Impairment

BACKGROUND

Donepezil is an acetylcholinesterase inhibitor frequently prescribed for the treatment of mild cognitive impairment (MCI) though not approved by the Food and Drug Administration for this indication. In Alzheimer's disease, butyrylcholinesterase (BChE) activity increases with disease progression and may replace acetylcholinesterase function. The most frequent polymorphism of BChE is the K-variant, which is associated with lower acetylcholine-hydrolyzing activity. BChE-K polymorphism has been studied in Alzheimer's disease progression and donepezil therapy, and has led to contradictory results.

OBJECTIVES

To determine whether BChE-K genotype predicts response to donepezil in MCI.

METHODS

We examined the association between BChE-K genotype and changes in cognitive function using the data collected during the ADCS vitamin E/donepezil clinical trial in MCI.

RESULTS

We found significant interactions between BChE-K genotype and the duration of donepezil treatment, with increased changes in MMSE and CDR-SB scores compared to the common allele in MCI subjects treated during the 3-year trial. We found faster MMSE decline and CDR-SB rise in BChE-K homozygous individuals treated with donepezil compared to the untreated. We observed similar interactions between BChE-K genotype and steeper changes in MMSE and CDR-SB scores in APOE4 carriers treated with donepezil compared to controls.

CONCLUSION

BChE-K polymorphisms are associated with deleterious changes in cognitive decline in MCI patients treated with donepezil for 3 years. This indicates that BChE-K genotyping should be performed to help identify subsets of subjects at risk for donepezil therapy, like those carrying APOE4. BChE-K and APOE4 carriers should not be prescribed off-label donepezil therapy for MCI management.

Butyrylcholinesterase and Acetylcholinesterase polymorphisms in Multiple Sclerosis patients: implication in peripheral inflammation

Multiple Sclerosis (MS) is an autoimmune disease, having not fully understood aetiology, and both genetic and environmental factors contribute to the pathogenesis of the disease. The cholinergic system has been indicated as a mediator of neuro-immune interactions, as well as an internal regulator of immune responses. The aim of the present research was to assess the associations between BChE and AChE genetic variations and serum cholinergic and inflammatory profiles in 102 Relapsing Remitting-MS patients and 117 healthy controls. An increased frequency of the BChE K-allele in MS patients as compared to controls was found. In addition, data showed that patients had higher BChE enzymatic activity, which is increased by the presence of the polymorphic allele and reduced amounts of circulating ACh. AChE polymorphism was significantly associated to reduced activity in both patients and controls. We propose that serum BChE and AChE activity may be used as a secondary markers to assess the role of non-neuronal cholinergic system in regulating peripheral inflammation via ACh regulation. This pilot study shed light on the role of the non-neuronal cholinergic system in immune cells to better understand MS pathogenesis. The cross-talk between the periphery and the CNS could have a new undescribed crucial role for MS, regarded as a systemic disease.

Low Plasma Cholinesterase Activities are Associated with Deficits in Spatial Orientation, Reduced Ability to Perform Basic Activities of Daily Living, and Low Body Mass Index in Patients with Progressed Alzheimer's Disease

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder characterized by a central cholinergic deficit. Non-neuronal cholinergic changes are, however, described as well. Here we focused on possible changes in the activity of the plasma cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), in hospitalized AD patients. We analyzed plasma AChE and BChE activities with regards to age, gender, body mass index (BMI), cognitive functions, and ability to perform activities of daily living in AD patients in comparison to healthy subjects. We observed lower AChE activity and trend toward lower BChE activity in AD patients, which both correlated with low BMI. AD patients unable to perform basic activities of daily living (feeding, bathing, dressing, and grooming) showed reduced plasma AChE activities, while worse spatial orientation was linked to lower BChE activities. Three out of four AD patients with the lowest BChE activities died within one year. In conclusion, progressed AD was accompanied by lower plasma AChE activity and trend toward lower BChE activity, which correlated with BMI and deficits in different components of the AD.

Genetic Association of CHAT rs3810950 and rs2177369 Polymorphisms with the Risk of Alzheimer's Disease: A Meta-Analysis

Choline acetyltransferase (CHAT) rs3810950 and rs2177369 polymorphisms have been implicated in susceptibility to Alzheimer's disease (AD). Due to the inconsistent results from previous studies, a meta-analysis was performed to estimate the association between these polymorphisms and AD risk more precisely. Pooled results of our meta-analysis indicated CHAT rs2177369 polymorphism was correlated with decreasing AD risk in one of five genetic models (dominant: OR = 0.77, 95% CI: 0.62–0.96), while rs3810950 mutant was associated with AD development in three models (allelic: OR = 1.18, 95% CI: 1.01–1.37, homozygous: OR = 1.63, 95% CI: 1.09–2.42, and recessive: OR = 1.65, 95% CI: 1.20–2.26). In subgroup analysis by ethnicity, the association between CHAT rs3810950 polymorphism and AD risk was just found in the recessive model (OR = 1.47, 95% CI: 1.05–2.07) among Caucasians, while four genetic models (allelic: OR = 1.23, 95% CI: 1.01–1.48; homozygous: OR = 2.24, 95% CI: 1.48–3.39; dominant: OR = 1.21, 95% CI: 1.06–1.40; and recessive: OR = 2.18, 95% CI: 1.45–3.29) assumed this association in Asians. In conclusion, our meta-analysis indicated CHAT rs2177369 polymorphism might play a protective role in AD, while rs3810950 variant was a risk factor for AD but its single heterozygous mutations might not influence susceptibility to AD.

Association of Choline Acetyltransferase Gene Polymorphisms (SNPs rs868750G/A, rs1880676G/A, rs2177369G/A and rs3810950G/A) with Alzheimer's Disease Risk: A Meta-Analysis

BACKGROUND

Epidemiological studies have investigated the role of choline acetyltransferase (ChAT) in Alzheimer's disease (AD). ChAT gene polymorphisms (SNPs rs868750G/A, rs1880676G/A, rs2177369G/A, and rs3810950G/A) may be associated with the risk of AD. In this meta-analysis, we determined the relationship between the four polymorphisms and the risk of AD.

METHODS

We searched MEDLINE, EMBASE, and HuGEnet databases for studies linking the four polymorphisms with AD risk. We included 16 articles in our meta-analysis to assess the association between the four polymorphisms and susceptibility to AD by calculating the pooled odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The combined results showed no significant association with rs1880676G/A and rs2177369G/A polymorphisms. The risk of AD (GG+GA versus AA: OR = 0.01, 95%CI = 0.01-0.02, P < 0.05; GG versus GA+AA: OR = 0.85, 95%CI = 0.72-1.00, P = 0.05; GA versus AA: OR = 0.60, 95% CI = 0.37-0.98, P = 0.04) with rs868750G/A polymorphism, or the association of rs3810950G/A polymorphism with AD risk in the overall population (GA versus AA: OR = 0.64, 95% CI = 0.44-0.93, P = 0.02; GG+GA versus AA: OR = 0.62, 95% CI = 0.39-0.97, P = 0.04) or Asian group (GA versus AA: OR = 0.50, 95% CI = 0.32-0.76, P = 0.001, and GG+GA versus AA: OR = 0.46, 95% CI = 0.30-0.09, P = 0.0002) was demonstrated.

CONCLUSIONS

Our meta-analysis suggested that rs1880670G/A, and rs2177369 G/A polymorphisms were not risk factors for AD. However, rs3810950G/A, or rs868750G/A genetic polymorphism was a genetic risk factor for the development of AD. The rs3810950G/A polymorphism had a negative effect on the risk of AD for GA or GG+GA genotypes compared with AA in the overall population or Asians.

Polymorphisms of CHAT but not TFAM or VR22 are Associated with Alzheimer Disease Risk

Background

Alzheimer disease (AD) is a chronic neurodegenerative disease that is one of the most prevalent health problems among seniors. The cause of AD has not yet been elucidated, but many risk factors have been identified that might contribute to the pathogenesis and prognosis of AD. We conducted a meta-analysis of studies involving CHAT, TFAM, and VR22 polymorphisms and AD susceptibility to further understand the pathogenesis of AD.

Material/Methods

PubMed/Medline, Embase, Web of Science, the Cochrane Library, and Google Scholar were searched for relevant articles. Rs1880676, rs2177369, rs3810950, and rs868750 of CHAT; rs1937 and rs2306604 of TFAM; and rs10997691 and rs7070570 of VR22 are studied in this meta-analysis.

Results

A total of 51 case-control studies with 16 446 cases and 16 057 controls were enrolled. For CHAT, rs2177369 (G>A) in whites and rs3810950 (G>A) in Asians were found to be associated with AD susceptibility. No association was detected between rs1880676 and rs868750 and AD risk. For TFAM and VR22, no significant association was detected in studied single-nucleotide polymorphisms (SNPs).

Conclusions

Rs2177369 and rs3810950 of CHAT are associated with AD susceptibility, but rs1880676 and rs868750 are not. Rs1937 and rs2306604 of TFAM, and rs10997691 and rs7070570 of VR22 are not significantly associated with AD risk.

Influence of family history of dementia in the development and progression of late-onset Alzheimer's disease

Family history of dementia (FH) is a recognized risk factor for developing late-onset Alzheimer's disease (AD). We asked whether having FH increases AD risk and influences disease severity (age at onset and cognitive impairment) in 420 AD patients and 109 controls with (FH+) or without (FH-). The relationships of APOE and other AD risk genes with FH were analyzed as well. The proportion of APOE e4 allele carriers was higher among the FH+ than the FH- AD patients (49.6% vs. 38.9%; P = 0.04). The distribution of the risk genotypes of nine AD susceptibility genes previously examined (CHAT, CYP17, CYP19, ESR1, FSHR, P53, P73, P21, PPARG) did not differ between the FH+ and the FH- AD patients, indicating that none contributed significantly to familial clustering of disease. FH was associated with an increased AD risk (odds ratio [OR] 2.71, 95% confidence interval [CI] 1.44-5.09; P = 0.002) independent of carrying the APOE e4 allele (OR 2.61, 95%CI 1.53-4.44; P = 0.0004). Having a first-degree relative or a parent with dementia was significantly associated with AD risk (OR 2.9, 95%CI 1.3-6.4; P = 0.009 and OR 2.7, 95%CI 1.1-6.2; P = 0.02) but having a sibling with dementia was not (OR 1.7, 95%CI 0.2 to 14.7; P = 0.6). Among the FH+ AD patients, having one or both parents affected seemed to raise the risk of earlier onset age (P = 0.02) and greater cognitive impairment (P = 0.02) than having only an affected sibling, whereas having two or more affected relatives did not.

The Effect of Choline Acetyltransferase Genotype on Donepezil Treatment Response in Patients with Alzheimer's Disease

Objective

We examined the difference in responses to donepezil between carriers and non-carriers of the A allele at the +4 position of the choline acetyltransferase (ChAT) gene in Koreans.

Methods

Patients who met the criteria for probable Alzheimer’s disease (AD) (n=199) were recruited. Among these, 145 completed the 12-week follow-up evaluation and 135 completed the 26-week scheduled course. Differences and changes in the Korean version of the mini-mental state examination (MMSE-KC) score, Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease Neuropsychological Assessment Battery (CERAD-K[N]) wordlist subtest score (WSS), CERAD-K(N) total score (TS), and the Korean version of geriatric depression scale (GDS-K) score between baseline and 12 weeks or 26 weeks were assessed by the Student’s t-test.

Results

At 12 weeks, the changes in the MMSE-KC score, CERAD-K(N) WSS, and CERAD-K(N) TS from baseline were not significant between ChAT A allele carriers and non-carriers; however, at 26 weeks, these changes were significantly larger in ChAT A allele carriers than in non-carriers (p=0.02 for MMSE-KC and p=0.03 for CERAD-K(N) WSS respectively).

Conclusion

Our findings in this study suggested that presence of the A allele at the +4 position of ChAT might positively influence the treatment effect of donepezil in the early stages of AD in Koreans.

Association of BDNF and BCHE with Alzheimer's disease: Meta-analysis based on 56 genetic case-control studies of 12,563 cases and 12,622 controls

Alzheimer's disease (AD) is a common neurodegenerative disorder that can destroy the memory of sufferers and lead to distress for the individual and society. Brain-derived neurotrophic factor (BDNF) and butyrylcholinesterase (BCHE) are two genes associated with β-amyloid plaques and neurofibrillary tangles that are two key factors in the pathophysiology of AD. The aim of the current meta-analysis was to evaluate the association between BDNF Val66Met (rs6265), BDNF C270T (rs2030324) and BCHE-K (rs1803274) polymorphisms and AD. A comprehensive meta-analysis was performed using the online database PubMed without a time limitation. A total of 56 articles evaluating 12,563 cases and 12,622 controls were selected for the current meta-analysis. The results showed a moderate association of the BDNF C270T polymorphism with the risk of AD in Asians under a dominant model (P=0.03; odds ratio, 1.88; 95% confidence interval, 1.08-3.27). No other significant association was found during the meta-analysis for the other two polymorphisms (P>0.05). The current meta-analysis suggests that BDNF C270T is a risk factor for AD in Asians. This meta-analysis has been, to the best of our knowledge, the most comprehensive meta-analysis of BDNF Val66Met, BDNF C270T and BCHE-K to date.

Sex and ESR1 genotype may influence the response to treatment with donepezil and rivastigmine in patients with Alzheimer's disease

BACKGROUND

Many factors could be responsible for the different response to treatment with the cholinesterase inhibitors (ChEIs) donepezil and rivastigmine in Alzheimer's disease (AD) patients. Sex and the variants of the estrogen receptor α (ESR1) gene are reported to modulate AD susceptibility or the course of the disease. The aim of the present study was to verify whether patient's sex and ESR1 genotype could influence the response to ChEI treatment, as there is evidence that estrogens affect cholinergic system functioning.

METHODS

Two ESR1 intronic polymorphisms (PvuII, rs2234693; XbaI, rs9340799) were examined in 184 AD patients: 157 were receiving treatment with donepezil or rivastigmine and 27 were receiving no treatment. Cognitive status was assessed using the mini mental state examination at four time points (1, 3, 9, and 15 months into therapy).

RESULTS

Among the patients under treatment with either ChEI, the women responded more markedly than the men. As compared with the untreated patients, the effects of treatment were statistically significant for both donepezil and rivastigmine. A significant effect of ESR1 genotypes was observed for the donepezil-treated patients, among which those carrying at least one copy of P and X alleles showed a significantly lower cognitive decline than the noncarriers.

CONCLUSIONS

The present data seem to confirm a sex-related influence on treatment, as the women seemed to be more sensitive to therapy and to have experienced less cognitive decline. ESR1 may be another gene contributing to interindividual variability in response to treatment with ChEIs.

CHRNA7 polymorphisms and response to cholinesterase inhibitors in Alzheimer's disease

Background

CHRNA7 encodes the α7 nicotinic acetylcholine receptor subunit, which is important to Alzheimer's disease (AD) pathogenesis and cholinergic neurotransmission. Previously, CHRNA7 polymorphisms have not been related to cholinesterase inhibitors (ChEI) response.

Methods

Mild to moderate AD patients received ChEIs were recruited from the neurology clinics of three teaching hospitals from 2007 to 2010 (n = 204). Nine haplotype-tagging single nucleotide polymorphisms of CHRNA7 were genotyped. Cognitive responders were those showing improvement in the Mini-Mental State Examination score ≧2 between baseline and 6 months after ChEI treatment.

Results

AD women carrying rs8024987 variants [GG+GC vs. CC: adjusted odds ratio (AOR) = 3.62, 95% confidence interval (CI) = 1.47–8.89] and GG haplotype in block1 (AOR = 3.34, 95% CI = 1.38–8.06) had significantly better response to ChEIs (false discovery rate <0.05). These variant carriers using galantamine were 11 times more likely to be responders than female non-carriers using donepezil or rivastigmine.

Conclusion

For the first time, this study found a significant association between CHRNA7 polymorphisms and better ChEI response. If confirmed by further studies, CHRNA7 polymorphisms may aid in predicting ChEI response and refining treatment choice.

Pharmacogenomics in neurology: current state and future steps

In neurology, as in any other clinical specialty, there is a need to develop treatment strategies that allow stratification of therapies to optimize efficacy and minimize toxicity. Pharmacogenomics is one such method for therapy optimization: it aims to elucidate the relationship between human genome sequence variation and differential drug responses. Approaches have focused on candidate approaches investigating absorption-, distribution-, metabolism, and elimination (ADME)-related genes (pharmacokinetic pathways), and potential drug targets (pharmacodynamic pathways). To date, however, only few genetic variants have been incorporated into clinical algorithms. Unfortunately, a large number of studies have thrown up contradictory results due to a number of deficiencies, including small sample sizes, inadequate phenotyping, and genotyping strategies. Thus, there still exists an urgent need to establish biomarkers that could help to select for patients with an optimal benefit to risk relationship. Here we review recent advances, and limitations, in pharmacogenomics for agents used in neuroimmunology, neurodegenerative diseases, ischemic stroke, epilepsy, and primary headaches. Further work is still required in all of these areas, which really needs to progress on several fronts, including better standardized phenotyping, appropriate sample sizes through multicenter collaborations and judicious use of new technological advances such as genome-wide approaches, next generation sequencing and systems biology. In time, this is likely to lead to improvements in the benefit-harm balance of neurological therapies, cost efficiency, and identification of new drugs.

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.

Genetic variants in the choline acetyltransferase (ChAT) gene are modestly associated with normal cognitive function in the elderly

Genetic variants in the choline acetyltransferase (ChAT) gene have been suggested as risk factors for neurodegenerative Alzheimer's disease (AD). Here we tested the importance of genetic variants in the ChAT gene in normal cognitive function of elderly in a study sample of Danish twins and singletons (N = 2070). The ChAT rs3810950 A allele, which has been associated with increased risk for AD, was found to be associated with a decrease cognitive status evaluated by a five-component cognitive composite score [P = 0.03, regression coefficient -0.30, 95% confidence interval (CI) -0.57 to -0.02], and the rs3810950 and rs8178990 ancestral GC haplotype was also associated with better cross-sectional cognitive composite score (P = 0.04, regression coefficient 0.59, 95% CI 0.03 to 1.16). Growth curve model analyses applied to up to 10 years of follow-up data showed that the rs3810950 A allele was associated with a lower cognitive composite score and Mini Mental State Examination at the lowest age (73 years of age), and was lower in the whole interval 73-82 although the absolute difference became smaller with age. Stratification by the presence of the APOE ε4 allele showed that rs3810950 AG/non-APOE ε4 carriers and rs3810950 AA/APOE ε4 carriers were associated with a lower cognitive composite score in younger elderly 73-83 years of age, similar to previous reports of association with AD.

Genetic variation in the choline O-acetyltransferase gene in depression and Alzheimer's disease: the VITA and Milano studies

Linkage studies point to the long arm of chromosome 10 being a susceptibility region for Alzheimer's disease (AD). Additionally, the gene choline O-acetyltransferase (CHAT) located on chromosome 10 was discussed for conveying risk towards AD, but the results are ambiguous. We examined a possible association of nineteen single-nucleotide polymorphisms (SNPs) in the CHAT gene in a longitudinal cohort study, the Vienna Tansdanube Aging (VITA)-study, in which all subjects were 75 years old at baseline. For replication, we used a more heterogeneous case-control sample from Milano with early and late AD. Nominal allelic and genotypic associations with AD risk in the cross-sectional VITA sample were found for rs3810950 (p = 0.038 for genotype, OR = 1.66 95% CI 1.03-2.68, p = 0.052 allele-wise). When combining both VITA- and Milano study rs3810950 was significantly associated with AD (p(combined) = 0.01634; power = 82%). This association was highly significant for APOEε4 carriers (p = 0.009 for genotype, OR = 3.21 95% CI 1.43-7.19 p = 0.007 allele-wise). Furthermore, an association of rs1880676 with AD was specific to carriers of the APOEε4 risk allele (p = 0.008, genotype; OR = 3.47 95% CI 1.50-8.01 p = 0.005 allele-wise). For depressive symptoms, we found a nominally significant association of rs3810950 with minor and major depression (p = 0.023, genotype; p = 0.008, allele). Applying Benjamini and Hochberg correction these associations could not be confirmed and also not be replicated in the more heterogeneous Milano sample. While our data therefore do not seem to support a major role for CHAT genetic variation in geriatric depression and AD, there might be a minor contribution in geriatric patients with depression and late onset AD, in particular those carrying the APOEε4 genotype.

Naturally occurring variations in the human cholinesterase genes: heritability and association with cardiovascular and metabolic traits

Cholinergic neurotransmission in the central and autonomic nervous systems regulates immediate variations in and longer-term maintenance of cardiovascular function with acetylcholinesterase (AChE) activity that is critical to temporal responsiveness. Butyrylcholinesterase (BChE), largely confined to the liver and plasma, subserves metabolic functions. AChE and BChE are found in hematopoietic cells and plasma, enabling one to correlate enzyme levels in whole blood with hereditary traits in twins. Using both twin and unrelated subjects, we found certain single nucleotide polymorphisms (SNPs) in the ACHE gene correlated with catalytic properties and general cardiovascular functions. SNP discovery from ACHE resequencing identified 19 SNPs: 7 coding SNPs (cSNPs), of which 4 are nonsynonymous, and 12 SNPs in untranslated regions, of which 3 are in a conserved sequence of an upstream intron. Both AChE and BChE activity traits in blood were heritable: AChE at 48.8 ± 6.1% and BChE at 81.4 ± 2.8%. Allelic and haplotype variations in the ACHE and BCHE genes were associated with changes in blood AChE and BChE activities. AChE activity was associated with BP status and SBP, whereas BChE activity was associated with features of the metabolic syndrome (especially body weight and BMI). Gene products from cDNAs with nonsynonymous cSNPs were expressed and purified. Protein expression of ACHE nonsynonymous variant D134H (SNP6) is impaired: this variant shows compromised stability and altered rates of organophosphate inhibition and oxime-assisted reactivation. A substantial fraction of the D134H instability could be reversed in the D134H/R136Q mutant. Hence, common genetic variations at ACHE and BCHE loci were associated with changes in corresponding enzymatic activities in blood.

Variation of the butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) genes in coronary artery disease

Butyrylcholinesterase (BChE) and acetylcholinesterase (AchE) are two enzymes of the cholinergic system putatively involved in coronary artery disease (CAD). We investigated two single nucleotide polymorphisms (SNPs) of the genes encoding these enzymes to determine whether some allele or genotype might represent a factor of risk or protection for CAD onset. AChE rs2571598 and BChE rs1803274 (the so-called K-variant) SNPs were investigated in a sample of 199 patients and 199 healthy subjects. No significant results were obtained for BChE, whereas for AChE the A allele was found significantly more frequent in patients than in controls (0.437 vs. 0.332; p=0.002). The crude Odds Ratio (OR) for CAD conferred by carrying the A allele was 1.76 (95% confidence interval [CI] 1.17-2.65). Stratification of the sample by gender revealed that the statistical significance was limited to female, where the crude OR associated with the A allele was 3.26 (95% CI 1.58-6.73). The lipidic pattern was also tested and related to variation of the two SNPs. In this case, an at limits significant result (p=0.03) was obtained for BChE, whose A allele (the K variant) in patients was found associated with higher plasma concentrations of high density lipoprotein-cholesterol.

Genetic influences on neural plasticity

Neural plasticity refers to the capability of the brain to alter function or structure in response to a range of events and is a crucial component of both functional recovery after injury and skill learning in healthy individuals. A number of factors influence neural plasticity and recovery of function after brain injury. The current review considers the impact of genetic factors. Polymorphisms in the human genes coding for brain-derived neurotrophic factor and apolipoprotein E have been studied in the context of plasticity and stroke recovery and are discussed here in detail. Several processes involved in plasticity and stroke recovery, such as depression or pharmacotherapy effects, are modulated by other genetic polymorphisms and are also discussed. Finally, new genetic polymorphisms that have not been studied in the context of stroke are proposed as new directions for study. A better understanding of genetic influences on recovery and response to therapy might allow improved treatment after a number of forms of central nervous system injury.

Managing cognitive dysfunction through the continuum of Alzheimer's disease: role of pharmacotherapy

It has been shown that, during several years preceding the diagnosis of Alzheimer's disease there is a gradual cognitive decline with a continuum between the pre-dementia stage (still known as the prodromal stage but now included within the general concept of mild cognitive impairment [MCI]) and the other stages of the disease. In MCI, the use of cholinesterase inhibitors (ChEIs) is not associated with any delay in the onset of Alzheimer's disease or dementia. During the dementia stages, the three ChEIs (donepezil, galantamine and rivastigmine) are efficacious for mild to moderate Alzheimer's disease; therefore, monotherapy with a ChEI can be envisaged as initial treatment. Confirmation of the efficacy of ChEIs in the mild dementia stage is essentially based on the results from a single, randomized study carried out specifically among patients at this stage of severity. Memantine can represent an alternative to ChEIs in the moderate stage of Alzheimer's disease. At the severe stage of the disease, memantine and donepezil are currently indicated. Indeed, memantine has been approved by numerous drug regulatory agencies for use in severe stages of the disease, whereas donepezil has only been approved by the US FDA. There is currently insufficient evidence for recommending combination therapy in Alzheimer's disease.

Effect of apolipoprotein E and butyrylcholinesterase genotypes on cognitive response to cholinesterase inhibitor treatment at different stages of Alzheimer's disease

Factors that influence response to drug treatment are of increasing importance. We report an analysis of genetic factors affecting response to cholinesterase inhibitor therapy in 165 subjects with Alzheimer's disease (AD). The presence of apolipoprotein E ε4 (APOE ε4) allele was associated with early and late cognitive response to cholinesterase inhibitor treatment in mild AD (Mini-Mental State Examination (MMSE) ≥21) (P<0.01). In moderate-to-severe AD (MMSE ≤15), presence of the BCHE-K variant was associated with late response to cholinesterase inhibitor treatment (P=0.02). Testing for APOE and BCHE genotypes may be useful in therapeutic decision making.

BuChE K variant is decreased in Alzheimer's disease not in fronto-temporal dementia

Alzheimer's disease (AD) is characterized by a significant reduction in AcetylCholinesterase and an increase in ButyrylCholinesterase (BuChE) activity. The existence of polymorphic regions on the BuChE gene has been previously described; the most frequently found polymorphism is the so-called K variant, which leads to a 30% decreased enzymatic activity. Different studies reported a positive association between K variant and AD, strongest among late-onset AD and Apolipoprotein E (APOE) e4 carriers. We analyzed APOE and BuChE polymorphisms in 167 AD and 59 fronto-temporal dementia (FTD) patients compared with 129 healthy controls (HC). We reported a significantly lower frequency of the BuChE K variant in AD compared with HC and FTD and a significant increased frequency of the K variant in FTD. These results are in agreement with the known increase of the BuChE activity in AD and support the evidence of different molecular pathways involved in the pathogenesis of AD and FTD.

Brain plasticity and genetic factors

Brain plasticity refers to changes in brain function and structure that arise in a number of contexts. One area in which brain plasticity is of considerable interest is recovery from stroke, both spontaneous and treatment-induced. A number of factors influence these poststroke brain events. The current review considers the impact of genetic factors. Polymorphisms in the human genes coding for brain-derived neurotrophic factor (BDNF) and apolipoprotein E (ApoE) have been studied in the context of plasticity and/or stroke recovery and are discussed here in detail. Several other genetic polymorphisms are indirectly involved in stroke recovery through their modulating influences on processes such as depression and pharmacotherapy effects. Finally, new genetic polymorphisms that have not been studied in the context of stroke are proposed as new directions for study. A better understanding of genetic influences on recovery and response to therapy might allow improved treatment after stroke.