Projections of Alzheimer's disease in the United States and the public health impact of delaying disease onset

Polygenic Risk Scores in Alzheimer's Disease: Current Applications and Future Directions

Genome-wide association studies have identified nearly 40 genome-wide significant single nucleotide polymorphisms (SNPs) which are associated with Alzheimer's Disease (AD). Due to the polygenicity of AD, polygenic risk scores (PRS) have shown high potential for AD risk prediction. PRSs have been shown to successfully discriminate between AD cases and controls achieving a prediction accuracy of up to 84% based on area under the receiver operating curve. The prediction accuracy in AD is higher compared with other complex genetic disorders. PRS can be restricted to SNPs which reside in biologically relevant gene-sets; the predictive value of these gene-sets in the general population is not as high as genome-wide PRS, but they may play an important role to identify mechanisms of disease development and inform biological experiments. Multiple methods are available to derive PRSs, such as selecting SNPs based on statistical evidence of association with the disease or using prior evidence for SNP selection. All methods have advantages, but PRS produced using different methodologies are often not comparable, and results should be interpreted with care. Similarly, this is true when PRS is based on different background populations. With the exponential growth in development of digital electronic devices it is easy to calculate an individual's disease risk using public databases. A major limitation for the utility of PRSs is that the risk score is sample and method dependent. Therefore, replicability and interpretability of PRS is an important issue. PRS can be used to determine the probability of developing disease which incorporates information about disease risk in the general population or in a specific AD risk group. It is essential to consult with genetic counselors to ensure genetic risk is communicated appropriately.

Generating national projections of dementia cases for Ireland using a calibrated macro-simulation model

INTRODUCTION

Epidemiological data on dementia is not available in many European countries and regions due to the high cost and complexity of conducting large scale dementia screening studies. The available epidemiological studies identify potentially substantial variation in the prevalence of dementia over time and across Europe.

METHODS

In this paper we generate simulations of the number of dementia cases in Ireland from 1991 to 2036 using a three-state Markov illness-death model. Parameters values are selected for each simulation from a range using a random parameter search pattern. We employ a novel calibration method which exploits the strong relationship between dementia, ageing and mortality. Simulation weights are generated based on differences between observed and modelled cohorts of older people and the reported number of deaths from dementia. Irish Census data from 1991 to 2016 and the number of recorded deaths due to dementia in 2018 are used as calibration points. A weighted average projection of the number of dementia cases is generated.

RESULTS

We estimate a weighted average number of cases of dementia in 2016 of 54 877 increasing to 98 946 in 2036; this estimate is substantially lower than the estimates generated using extrapolation methods. We show the wide range of possible outcomes given the range in the available parameter estimates and show that irrespective of whether the incidence rate of dementia is declining the number of cases of dementia is rapidly increasing due to population ageing.

CONCLUSION

Previous studies have used parameter estimates from meta-analyses of the literature or from individual studies. In this paper we supplement these with a calibration approach using observed cause of death and population age structure data. These additional sources of data can be used to generate estimates of dementia prevalence in any country or region which has census data and data on deaths due to dementia.

Defining and predicting transdiagnostic categories of neurodegenerative disease

The prevalence of concomitant proteinopathies and heterogeneous clinical symptoms in neurodegenerative diseases hinders the identification of individuals who might be candidates for a particular intervention. Here, by applying an unsupervised clustering algorithm to post-mortem histopathological data from 895 patients with degeneration in the central nervous system, we show that six non-overlapping disease clusters can simultaneously account for tau neurofibrillary tangles, α-synuclein inclusions, neuritic plaques, inclusions of the transcriptional repressor TDP-43, angiopathy, neuron loss and gliosis. We also show that membership to the six transdiagnostic disease clusters, which explains more variance in cognitive phenotypes than can be explained by individual diagnoses, can be accurately predicted from scores of the Mini-Mental Status Exam, protein levels in cerebrospinal fluid, and genotype at the APOE and MAPT loci, via cross-validated multiple logistic regression. This combination of unsupervised and supervised data-driven tools provides a framework that could be used to identify latent disease subtypes in other areas of medicine.

World-Wide FINGERS Network: A global approach to risk reduction and prevention of dementia

Reducing the risk of dementia can halt the worldwide increase of affected people. The multifactorial and heterogeneous nature of late-onset dementia, including Alzheimer’s disease (AD), indicates a potential impact of multidomain lifestyle interventions on risk reduction. The positive results of the landmark multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) support such an approach. The World-Wide FINGERS (WW-FINGERS), launched in 2017 and including over 25 countries, is the first global network of multidomain lifestyle intervention trials for dementia risk reduction and prevention. WW-FINGERS aims to adapt, test, and optimize the FINGER model to reduce risk across the spectrum of cognitive decline—from at-risk asymptomatic states to early symptomatic stages—in different geographical, cultural, and economic settings. WW-FINGERS aims to harmonize and adapt multidomain interventions across various countries and settings, to facilitate data sharing and analysis across studies, and to promote international joint initiatives to identify globally implementable and effective preventive strategies.

Centenarians as Models of Resistance and Resilience to Alzheimer's Disease and Related Dementias

The majority of research to understand the pathogenesis of and contributors to Alzheimer’s disease (AD) pathology, dementia, and disease progression has focused on studying individuals who have the disease or are at increased risk of having the disease. Yet there may be much to learn from individuals who have a paradoxical decreased risk of AD suggesting underlying protective factors. Centenarians demonstrate exceptional longevity that for a subset of the cohort is associated with an increased health span characterized by the delay or escape of age-related diseases including dementia. Here, I give evidence of the association of exceptional longevity with resistance and resilience to AD and describe how cohorts of centenarians and their offspring may serve as models of neuroprotection from AD. Discoveries of novel genetic, environmental, and behavioral factors that are associated with a decreased risk of AD may inform the development of interventions to slow or prevent AD in the general population. Centenarian cohorts may also be instrumental in serving as controls to individuals with AD to identify additional risk factors.

The role of diet in preventing and reducing cognitive decline

PURPOSE OF REVIEW

This review summarises the most recent evidence regarding the effects of diet in preventing and reducing age-related cognitive decline and neurodegenerative diseases.

RECENT FINDINGS

Recent evidence indicates that nutraceuticals and whole diet approaches may protect against the development of age-related cognitive decline and pathological neurodegeneration. The neuroprotective effects are diverse depending on the nutrient employed and may involve a reduction of neuroinflammation, an activation of the endogenous antioxidant defence system and a modulation of the gut microbiota structure and function.

SUMMARY

This review summarises the existing evidence in favour of diet as a viable alternative approach to directly impact cognitive decline and neurodegenerative diseases. The single nutrient (polyphenols, B vitamins, long-chain polyunsaturated fatty acids) versus whole diet approach (Mediterranean diet, Dietary Approaches to Stop Hypertension, MIND, Nordic, ketogenic) is presented and discussed. Potential mechanisms of action underlying the beneficial effects of these diets are also described. Implementation of large-scale preventive interventions based on dietary patterns identified as being beneficial to brain health should be a research and public health priority, ideally in conjunction with other health-promoting lifestyle factors.

Healthy lifestyle and the risk of Alzheimer dementia: Findings from 2 longitudinal studies

OBJECTIVE

To quantify the impact of a healthy lifestyle on the risk of Alzheimer dementia.

METHODS

Using data from the Chicago Health and Aging Project (CHAP; n = 1,845) and the Rush Memory and Aging Project (MAP; n = 920), we defined a healthy lifestyle score on the basis of nonsmoking, ≥150 min/wk moderate/vigorous-intensity physical activity, light to moderate alcohol consumption, high-quality Mediterranean-DASH Diet Intervention for Neurodegenerative Delay diet (upper 40%), and engagement in late-life cognitive activities (upper 40%), giving an overall score ranging from 0 to 5. Cox proportional hazard models were used for each cohort to estimate the hazard ratio (HR) and 95% confidence interval (CI) of the lifestyle score with Alzheimer dementia, and a random-effect meta-analysis was used to pool the results.

RESULTS

During a median follow-up of 5.8 years in CHAP and 6.0 years in MAP, 379 and 229 participants, respectively, had incident Alzheimer dementia. In multivariable-adjusted models, the pooled HR (95% CI) of Alzheimer dementia across 2 cohorts was 0.73 (95% CI 0.66-0.80) per each additional healthy lifestyle factor. Compared to participants with 0 to 1 healthy lifestyle factor, the risk of Alzheimer dementia was 37% lower (pooled HR 0.63, 95% CI 0.47-0.84) in those with 2 to 3 healthy lifestyle factors and 60% lower (pooled HR 0.40, 95% CI 0.28-0.56) in those with 4 to 5 healthy lifestyle factors.

CONCLUSION

A healthy lifestyle as a composite score is associated with a substantially lower risk of Alzheimer's dementia.

Pharmacokinetic Evaluation by Modeling and Simulation Analysis of a Donepezil Patch Formulation in Healthy Male Volunteers

Introduction

This study characterized the pharmacokinetics (PKs) of a donepezil patch formulation currently under development, using mixed effect modeling analysis, and explored optimal patch dosing regimens in comparison with the donepezil oral formulation.

Methods

PK data used in this analysis were from 60 healthy Korean male subjects participating in two Phase I studies, where subjects received single or multiple doses of donepezil of 43.75, 87.5, and 175 mg via patches, and 12 of them received a single oral dose of 10 mg of donepezil, followed by a single dose of donepezil via a patch. Donepezil PKs were analyzed by nonlinear mixed effect modeling using NONMEM software.

Results

A well-stirred model with two-compartment distribution and delayed absorption was chosen as the best model for the oral formulation. The PKs of donepezil after the patch applications were best described by a two-compartment linear model with zero-order absorption (D2) and absorption delay. The relative bioavailability (BA) of donepezil after the patch application compared with oral dosing was described to be affected by the duration of patch application.

Conclusion

PK simulations based on the chosen PK models suggested that, overall, donepezil exposure in plasma is similar whether with 10 mg of oral donepezil every 24 h or a 175 mg patch every 72 h, and likewise with 5 mg of oral donepezil every 24 h or an 87.5 mg patch every 72 h.

Midlife Chronological and Endocrinological Transitions in Brain Metabolism: System Biology Basis for Increased Alzheimer's Risk in Female Brain

Decline in brain glucose metabolism is a hallmark of late-onset Alzheimer’s disease (LOAD). Comprehensive understanding of the dynamic metabolic aging process in brain can provide insights into windows of opportunities to promote healthy brain aging. Chronological and endocrinological aging are associated with brain glucose hypometabolism and mitochondrial adaptations in female brain. Using a rat model recapitulating fundamental features of the human menopausal transition, results of transcriptomic analysis revealed stage-specific shifts in bioenergetic systems of biology that were paralleled by bioenergetic dysregulation in midlife aging female brain. Transcriptomic profiles were predictive of outcomes from unbiased, discovery-based metabolomic and lipidomic analyses, which revealed a dynamic adaptation of the aging female brain from glucose centric to utilization of auxiliary fuel sources that included amino acids, fatty acids, lipids, and ketone bodies. Coupling between brain and peripheral metabolic systems was dynamic and shifted from uncoupled to coupled under metabolic stress. Collectively, these data provide a detailed profile across transcriptomic and metabolomic systems underlying bioenergetic function in brain and its relationship to peripheral metabolic responses. Mechanistically, these data provide insights into the complex dynamics of chronological and endocrinological bioenergetic aging in female brain. Translationally, these findings are predictive of initiation of the prodromal / preclinical phase of LOAD for women in midlife and highlight therapeutic windows of opportunity to reduce the risk of late-onset Alzheimer’s disease.

Polygenic risk and pleiotropy in neurodegenerative diseases

In this paper we explore the phenomenon of pleiotropy in neurodegenerative diseases, focusing on Alzheimer's disease (AD). We summarize the various techniques developed to investigate pleiotropy among traits, elaborating in the polygenic risk scores (PRS) analysis. PRS was designed to assess a cumulative effect of a large number of SNPs for association with a disease and, later for disease risk prediction. Since genetic predictions rely on heritability, we discuss SNP-based heritability from genome-wide association studies and its contribution to the prediction accuracy of PRS. We review work examining pleiotropy in neurodegenerative diseases and related phenotypes and biomarkers. We conclude that the exploitation of pleiotropy may aid in the identification of novel genes and provide further insights in the disease mechanisms, and along with PRS analysis, may be advantageous for precision medicine.

Aspirin and other non-steroidal anti-inflammatory drugs for the prevention of dementia

BACKGROUND

Dementia is a worldwide concern. Its global prevalence is increasing. At present, there is no medication licensed to prevent or delay the onset of dementia. Inflammation has been suggested as a key factor in dementia pathogenesis. Therefore, medications with anti-inflammatory properties could be beneficial for dementia prevention.

OBJECTIVES

To evaluate the effectiveness and adverse effects of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) for the primary or secondary prevention of dementia.

SEARCH METHODS

We searched ALOIS, the specialised register of the Cochrane Dementia and Cognitive Improvement Group up to 9 January 2020. ALOIS contains records of clinical trials identified from monthly searches of several major healthcare databases, trial registries and grey literature sources. We ran additional searches across MEDLINE (OvidSP), Embase (OvidSP) and six other databases to ensure that the searches were as comprehensive and up-to-date as possible. We also reviewed citations of reference lists of included studies.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing aspirin or other NSAIDs with placebo for the primary or secondary prevention of dementia. We included trials with cognitively healthy participants (primary prevention) or participants with mild cognitive impairment (MCI) or cognitive complaints (secondary prevention).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures according to the Cochrane Handbook for Systematic Reviews of Interventions. We rated the strength of evidence for each outcome using the GRADE approach.

MAIN RESULTS

We included four RCTs with 23,187 participants. Because of the diversity of these trials, we did not combine data to give summary estimates, but presented a narrative description of the evidence. We identified one trial (19,114 participants) comparing low-dose aspirin (100 mg once daily) to placebo. Participants were aged 70 years or older with no history of dementia, cardiovascular disease or physical disability. Interim analysis indicated no significant treatment effect and the trial was terminated slightly early after a median of 4.7 years' follow-up. There was no evidence of a difference in incidence of dementia between aspirin and placebo groups (risk ratio (RR) 0.98, 95% CI 0.83 to 1.15; high-certainty evidence). Participants allocated aspirin had higher rates of major bleeding (RR 1.37, 95% CI 1.17 to 1.60, high-certainty evidence) and slightly higher mortality (RR 1.14, 95% CI 1.01 to 1.28; high-certainty evidence). There was no evidence of a difference in activities of daily living between groups (RR 0.84, 95% CI 0.70 to 1.02; high-certainty evidence). We identified three trials comparing non-aspirin NSAIDs to placebo. All three trials were terminated early due to adverse events associated with NSAIDs reported in other trials. One trial (2528 participants) investigated the cyclo-oxygenase-2 (COX-2) inhibitor celecoxib (200 mg twice daily) and the non-selective NSAID naproxen (220 mg twice daily) for preventing dementia in cognitively healthy older adults with a family history of Alzheimer's disease (AD). Median follow-up was 734 days. Combining both NSAID treatment arms, there was no evidence of a difference in the incidence of AD between participants allocated NSAIDs and those allocated placebo (RR 1.91, 95% CI 0.89 to 4.10; moderate-certainty evidence). There was also no evidence of a difference in rates of myocardial infarction (RR 1.21, 95% CI 0.61 to 2.40), stroke (RR 1.82, 95% CI 0.76 to 4.37) or mortality (RR 1.37, 95% CI 0.78 to 2.43) between treatment groups (all moderate-certainty evidence). One trial (88 participants) assessed the effectiveness of celecoxib (200 mg or 400 mg daily) in delaying cognitive decline in participants aged 40 to 81 years with mild age-related memory loss but normal memory performance scores. Mean duration of follow-up was 17.6 months in the celecoxib group and 18.1 months in the placebo group. There was no evidence of a difference between groups in test scores in any of six cognitive domains. Participants allocated celecoxib experienced more gastrointestinal adverse events than those allocated placebo (RR 2.66, 95% CI 1.05 to 6.75; low-certainty evidence). One trial (1457 participants) assessed the effectiveness of the COX-2 inhibitor rofecoxib (25 mg once daily) in delaying or preventing a diagnosis of AD in participants with MCI. Median duration of study participation was 115 weeks in the rofecoxib group and 130 weeks in the placebo group. There was a higher incidence of AD in the rofecoxib than the placebo group (RR 1.32, 95% CI 1.01 to 1.72; moderate-certainty evidence). There was no evidence of a difference between groups in cardiovascular adverse events (RR 1.07, 95% CI 0.68 to 1.66; moderate-certainty evidence) or mortality (RR 1.62, 95% CI 0.85 to 3.05; moderate-certainty evidence). Participants allocated rofecoxib had more upper gastrointestinal adverse events (RR 3.53, 95% CI 1.17 to 10.68; moderate-certainty evidence). Reported annual mean difference scores showed no evidence of a difference between groups in activities of daily living (year 1: no data available; year 2: 0.0, 95% CI -0.1 to 0.2; year 3: 0.1, 95% CI -0.1 to 0.3; year 4: 0.1, 95% CI -0.1 to 0.4; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There is no evidence to support the use of low-dose aspirin or other NSAIDs of any class (celecoxib, rofecoxib or naproxen) for the prevention of dementia, but there was evidence of harm. Although there were limitations in the available evidence, it seems unlikely that there is any need for further trials of low-dose aspirin for dementia prevention. If future studies of NSAIDs for dementia prevention are planned, they will need to be cognisant of the safety concerns arising from the existing studies.

Head circumference, apolipoprotein E genotype and cognition in the Bavarian School Sisters Study

Background

The apolipoprotein E (APOE) ɛ4 allele is correlated with an earlier onset of Alzheimer's disease symptoms; larger head circumference has been associated with an individual resilience against cognitive impairment.

Methods

We explored if larger head circumference attenuates the effect of the APOE ɛ4 allele on cognition in 380 Catholic sisters covering the spectrum from normal cognitive performance to severe dementia.

Results

Linear regression analysis, adjusting for risk factors for cognitive decline, revealed that APOE ɛ4 was correlated with worse cognition and that larger head circumference attenuated the negative effect of the ɛ4 allele on cognitive performance.

Conclusion

Larger head circumference (i.e. larger brain size) seems to be associated with greater resilience against genetic determinants of cognitive impairment, possibly due to enhanced brain or cognitive reserve.

Machine learning prediction of incidence of Alzheimer's disease using large-scale administrative health data

Nationwide population-based cohort provides a new opportunity to build an automated risk prediction model based on individuals' history of health and healthcare beyond existing risk prediction models. We tested the possibility of machine learning models to predict future incidence of Alzheimer's disease (AD) using large-scale administrative health data. From the Korean National Health Insurance Service database between 2002 and 2010, we obtained de-identified health data in elders above 65 years (N = 40,736) containing 4,894 unique clinical features including ICD-10 codes, medication codes, laboratory values, history of personal and family illness and socio-demographics. To define incident AD we considered two operational definitions: "definite AD" with diagnostic codes and dementia medication (n = 614) and "probable AD" with only diagnosis (n = 2026). We trained and validated random forest, support vector machine and logistic regression to predict incident AD in 1, 2, 3, and 4 subsequent years. For predicting future incidence of AD in balanced samples (bootstrapping), the machine learning models showed reasonable performance in 1-year prediction with AUC of 0.775 and 0.759, based on "definite AD" and "probable AD" outcomes, respectively; in 2-year, 0.730 and 0.693; in 3-year, 0.677 and 0.644; in 4-year, 0.725 and 0.683. The results were similar when the entire (unbalanced) samples were used. Important clinical features selected in logistic regression included hemoglobin level, age and urine protein level. This study may shed a light on the utility of the data-driven machine learning model based on large-scale administrative health data in AD risk prediction, which may enable better selection of individuals at risk for AD in clinical trials or early detection in clinical settings.

Alzheimer's Risk Factors Age, APOE Genotype, and Sex Drive Distinct Molecular Pathways

Evidence suggests interplay among the three major risk factors for Alzheimer's disease (AD): age, APOE genotype, and sex. Here, we present comprehensive datasets and analyses of brain transcriptomes and blood metabolomes from human apoE2-, apoE3-, and apoE4-targeted replacement mice across young, middle, and old ages with both sexes. We found that age had the greatest impact on brain transcriptomes highlighted by an immune module led by Trem2 and Tyrobp, whereas APOE4 was associated with upregulation of multiple Serpina3 genes. Importantly, these networks and gene expression changes were mostly conserved in human brains. Finally, we observed a significant interaction between age, APOE genotype, and sex on unfolded protein response pathway. In the periphery, APOE2 drove distinct blood metabolome profile highlighted by the upregulation of lipid metabolites. Our work identifies unique and interactive molecular pathways underlying AD risk factors providing valuable resources for discovery and validation research in model systems and humans.

Prevention of dementia presents a potentially critical platform for improvement of long-term public health

With the aging of the population, Alzheimer disease (AD) has become an epidemic and a major public health threat. Hundreds of molecules tested in clinical trials in the last decade to treat AD have failed, moving the field to examine the clinical and neurobiological value of prevention of cognitive decline and AD. This short review describes recently finished or currently ongoing clinical trials for prevention of AD, both their main outcomes and secondary outcomes. In addition, the potential modifying effects of age and of genetics as important factors that may affect the design of future clinical trials is discussed. Finally, we discuss the development of new molecular imaging and of digital technologies as a means to disclosure of dementia-related risk and disease progress, and their potential importance as contributors to adherence to healthy lifestyle for the prevention or delay of AD onset.

2020 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on caregivers and society. The Special Report discusses the future challenges of meeting care demands for the growing number of people living with Alzheimer's dementia in the United States with a particular emphasis on primary care. By mid-century, the number of Americans age 65 and older with Alzheimer's dementia may grow to 13.8 million. This represents a steep increase from the estimated 5.8 million Americans age 65 and older who have Alzheimer's dementia today. Official death certificates recorded 122,019 deaths from AD in 2018, the latest year for which data are available, making Alzheimer's the sixth leading cause of death in the United States and the fifth leading cause of death among Americans age 65 and older. Between 2000 and 2018, deaths resulting from stroke, HIV and heart disease decreased, whereas reported deaths from Alzheimer's increased 146.2%. In 2019, more than 16 million family members and other unpaid caregivers provided an estimated 18.6 billion hours of care to people with Alzheimer's or other dementias. This care is valued at nearly $244 billion, but its costs extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are more than three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 23 times as great. Total payments in 2020 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $305 billion. As the population of Americans living with Alzheimer's dementia increases, the burden of caring for that population also increases. These challenges are exacerbated by a shortage of dementia care specialists, which places an increasing burden on primary care physicians (PCPs) to provide care for people living with dementia. Many PCPs feel underprepared and inadequately trained to handle dementia care responsibilities effectively. This report includes recommendations for maximizing quality care in the face of the shortage of specialists and training challenges in primary care.

Liraglutide Protects Against Brain Amyloid-β1-42 Accumulation in Female Mice with Early Alzheimer's Disease-Like Pathology by Partially Rescuing Oxidative/Nitrosative Stress and Inflammation

Alzheimer’s disease (AD) is the most common form of dementia worldwide, being characterized by the deposition of senile plaques, neurofibrillary tangles (enriched in the amyloid beta (Aβ) peptide and hyperphosphorylated tau (p-tau), respectively) and memory loss. Aging, type 2 diabetes (T2D) and female sex (especially after menopause) are risk factors for AD, but their crosslinking mechanisms remain unclear. Most clinical trials targeting AD neuropathology failed and it remains incurable. However, evidence suggests that effective anti-T2D drugs, such as the GLP-1 mimetic and neuroprotector liraglutide, can be also efficient against AD. Thus, we aimed to study the benefits of a peripheral liraglutide treatment in AD female mice. We used blood and brain cortical lysates from 10-month-old 3xTg-AD female mice, treated for 28 days with liraglutide (0.2 mg/kg, once/day) to evaluate parameters affected in AD (e.g., Aβ and p-tau, motor and cognitive function, glucose metabolism, inflammation and oxidative/nitrosative stress). Despite the limited signs of cognitive changes in mature female mice, liraglutide only reduced their cortical Aβ_1–42 levels. Liraglutide partially attenuated brain estradiol and GLP-1 and activated PKA levels, oxidative/nitrosative stress and inflammation in these AD female mice. Our results support the earlier use of liraglutide as a potential preventive/therapeutic agent against the accumulation of the first neuropathological features of AD in females.

CLIC1 Protein Accumulates in Circulating Monocyte Membrane during Neurodegeneration

Pathologies that lead to neurodegeneration in the central nervous system (CNS) represent a major contemporary medical challenge. Neurodegenerative processes, like those that occur in Alzheimer’s disease (AD) are progressive, and at the moment, they are unstoppable. Not only is an adequate therapy missing but diagnosis is also extremely complicated. The most reliable method is the measurement of beta amyloid and tau peptides concentration in the cerebrospinal fluid (CSF). However, collecting liquid samples from the CNS is an invasive procedure, thus it is not suitable for a large-scale prevention program. Ideally, blood testing is the most manageable and appropriate diagnostic procedure for a massive population screening. Recently, a few candidates, including proteins or microRNAs present in plasma/serum have been identified. The aim of the present work is to propose the chloride intracellular channel 1 (CLIC1) protein as a potential marker of neurodegenerative processes. CLIC1 protein accumulates in peripheral blood mononuclear cells (PBMCs), and increases drastically when the CNS is in a chronic inflammatory state. In AD patients, both immunolocalization and mRNA quantification are able to show the behavior of CLIC1 during a persistent inflammatory state of the CNS. In particular, confocal microscopy analysis and electrophysiological measurements highlight the significant presence of transmembrane CLIC1 (tmCLIC1) in PBMCs from AD patients. Recent investigations suggest that tmCLIC1 has a very specific role. This provides an opportunity to use blood tests and conventional technologies to discriminate between healthy individuals and patients with ongoing neurodegenerative processes.

Phosphoinositide 3-kinase inhibitor AS605240 ameliorates streptozotocin-induced Alzheimer's disease like sporadic dementia in experimental rats

The quest for chemical entities able to curb the action of the phosphoinositide 3-kinase, (PI3K)/protein kinase B (AKT) signaling pathways is evolving as a potential therapeutic strategy for the treatment and/or prevention of neurodegenerative disorders including Alzheimer's disease (AD). In this study, the effects of a PI3K inhibitor, AS605240 on cognitive dysfunction and antioxidative defense parameters against intra-cerebroventricular-streptozotocin (ICV-STZ)-induced rat model of sporadic AD was evaluated. ICV administration of a single dose of STZ (3 mg/kg) was performed to induce behavioral and biochemical changes in rats using the stereotaxic technique. Animals were administered with varying doses of AS605240 (5, 10 and 15 mg/kg) orally, 1 h before ICV-STZ on day 1 and continued once daily for four weeks. The behavioral parameters (passive avoidance and Morris water maze), antioxidative defense parameters, amyloid-beta (Aβ) protein expression by Western blotting and immunostaining technique were estimated in brain tissue. AS605240 dose-dependently and significantly (p < 0.05 and p < 0.01 and p < 0.001) improved ICV-STZ-induced cognitive impairment and attenuated the altered antioxidative related parameters including superoxide dismutase, lipid peroxidation, glutathione and nitrite levels. Further, the increased Aβ protein expression levels in brain tissue were markedly restored with AS605240 treatment. In conclusion, our study demonstrated that AS605240 exhibited immense potential in attenuating STZ-induced sporadic AD features in rats and may be developed as a therapeutic agent in the treatment and management of sporadic AD.

Validation of Iranian Smell Identification Test for screening of mild cognitive impairment and Alzheimer's disease

Background: According to the World Alzheimer Report 2019, an estimated 50 million people worldwide are living with dementia. The smell test is a method for early detection of Alzheimer's disease (AD) as an inexpensive, simple, and noninvasive screening tool. This study aimed to evaluate the accuracy of the Iran Smell Identification Test (Iran-SIT) in discriminating patients with AD, with mild cognitive impairment (MCI), and the healthy subjects.Methods: In this study, 42 patients with AD, 33 with MCI, and 32 healthy controls were recruited from the referral Memory Clinic of Tehran University of Medical Sciences. The olfactory function was examined with six odors through Iran-SIT.Results: We found a significant difference among the olfactory function in subjects with normal cognitive status, that of those with MCI and those with AD (p < 0.001). The cutoff point for the diagnosis of AD was (sensitivity and specificity were, respectively, 85.7 and 90.8%), and (Sensitivity and specificity were, respectively, 93.9 and 100%) for MCI.Conclusion: These results suggest that Iran-SIT is a valid biomarker and practical screening tool, with simple, inexpensive, and readily available for use in combination with neuropsychological tools and neuroimaging for early detection of AD.

New Insights Into the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD), a common neurodegenerative disease in the elderly and the most prevalent cause of dementia, is characterized by progressive cognitive impairment. The prevalence of AD continues to increase worldwide, becoming a great healthcare challenge of the twenty-first century. In the more than 110 years since AD was discovered, many related pathogenic mechanisms have been proposed, and the most recognized hypotheses are the amyloid and tau hypotheses. However, almost all clinical trials targeting these mechanisms have not identified any effective methods to treat AD. Scientists are gradually moving away from the simple assumption, as proposed in the original amyloid hypothesis, to new theories of pathogenesis, including gamma oscillations, prion transmission, cerebral vasoconstriction, growth hormone secretagogue receptor 1α (GHSR1α)-mediated mechanism, and infection. To place these findings in context, we first reviewed the neuropathology of AD and further discussed new insights in the pathogenesis of AD.

Evidence in support of chromosomal sex influencing plasma based metabolome vs APOE genotype influencing brain metabolome profile in humanized APOE male and female mice

Late onset Alzheimer’s disease (LOAD) is a progressive neurodegenerative disease with four well-established risk factors: age, APOE4 genotype, female chromosomal sex, and maternal history of AD. Each risk factor impacts multiple systems, making LOAD a complex systems biology challenge. To investigate interactions between LOAD risk factors, we performed multiple scale analyses, including metabolomics, transcriptomics, brain magnetic resonance imaging (MRI), and beta-amyloid assessment, in 16 months old male and female mice with humanized human APOE3 (hAPOE3) or APOE4 (hAPOE4) genes. Metabolomic analyses indicated a sex difference in plasma profile whereas APOE genotype determined brain metabolic profile. Consistent with the brain metabolome, gene and pathway-based RNA-Seq analyses of the hippocampus indicated increased expression of fatty acid/lipid metabolism related genes and pathways in both hAPOE4 males and females. Further, female transcription of fatty acid and amino acids pathways were significantly different from males. MRI based imaging analyses indicated that in multiple white matter tracts, hAPOE4 males and females exhibited lower fractional anisotropy than their hAPOE3 counterparts, suggesting a lower level of white matter integrity in hAPOE4 mice. Consistent with the brain metabolomic and transcriptomic profile of hAPOE4 carriers, beta-amyloid generation was detectable in 16-month-old male and female brains. These data provide therapeutic targets based on chromosomal sex and APOE genotype. Collectively, these data provide a framework for developing precision medicine interventions during the prodromal phase of LOAD, when the potential to reverse, prevent and delay LOAD progression is greatest.

The Alzheimer's Prevention Registry: A Large Internet-Based Participant Recruitment Registry to Accelerate Referrals to Alzheimer's-Focused Studies

BACKGROUND

Recruitment for Alzheimer's disease (AD)-focused studies, particularly prevention studies, is challenging due to the public's lack of awareness about study opportunities coupled with studies' inclusion and exclusion criteria, resulting in a high screen fail rate.

OBJECTIVES

To develop an internet-based participant recruitment registry for efficiently and effectively raising awareness about AD-focused study opportunities and connecting potentially eligible volunteers to studies in their communities.

METHODS

Individuals age 18 and older are eligible to join the Alzheimer's Prevention Registry (APR). Individuals provide first and last name, year of birth, country, and zip/postal code to join the APR; for questions regarding race, ethnicity, sex, family history of AD or other dementia, and diagnosis of cognitive impairment, individuals have the option to select "prefer not to answer." The APR website maintains a list of recruiting studies and contacts members who have opted in by email when new studies are available for enrollment.

RESULTS

As of December 1, 2019, 346,661 individuals had joined the APR. Members had a mean age of 63.3 (SD 11.7) years and were predominately women (75%). 94% were cognitively unimpaired, 50% reported a family history of AD or other dementia, and of those who provided race, 76% were white. 39% joined the APR as a result of a paid social media advertisement. To date, the APR helped recruit for 82 studies.

CONCLUSIONS

The APR is a large, internet-based participant recruitment registry designed to raise awareness about AD prevention research and connect members with enrolling studies in their communities. It has demonstrated the ability to recruit and engage a large number of highly motivated members and assist researchers in meeting their recruitment goals. Future publications will report on the effectiveness of APR for accelerating recruitment and enrollment into AD-focused studies.

The promises and pitfalls of sex difference research

Funding agencies in North America and Europe are recognizing the importance of the integration of sex differences into basic and clinical research. Although these mandates are in place to improve our knowledge of health for both men and women, there have been a number of implementation issues that require vigilance on the part of funders and the research community. Here we discuss issues on simple inclusion of both sexes in studies to specialisation of sex differences with attention paid to statistics and the need for sex-specific treatments. We suggest differing mandates need to be considered regarding simple integration versus the need for studies in the specialisation of sex differences and/or the need for research that recognises the importance of male-specific or female-specific factors that influence subsequent health such as menstruation, menopause or pregnancy.

The Alzheimer's Prevention Registry: A Large Internet-Based Participant Recruitment Registry to Accelerate Referrals to Alzheimer's-Focused Studies

BACKGROUND

Recruitment for Alzheimer's disease (AD)-focused studies, particularly prevention studies, is challenging due to the public's lack of awareness about study opportunities coupled with studies' inclusion and exclusion criteria, resulting in a high screen fail rate.

OBJECTIVES

To develop an internet-based participant recruitment registry for efficiently and effectively raising awareness about AD-focused study opportunities and connecting potentially eligible volunteers to studies in their communities.

METHODS

Individuals age 18 and older are eligible to join the Alzheimer's Prevention Registry (APR). Individuals provide first and last name, year of birth, country, and zip/postal code to join the APR; for questions regarding race, ethnicity, sex, family history of AD or other dementia, and diagnosis of cognitive impairment, individuals have the option to select "prefer not to answer." The APR website maintains a list of recruiting studies and contacts members who have opted in by email when new studies are available for enrollment.

RESULTS

As of December 1, 2019, 346,661 individuals had joined the APR. Members had a mean age of 63.3 (SD 11.7) years and were predominately women (75%). 94% were cognitively unimpaired, 50% reported a family history of AD or other dementia, and of those who provided race, 76% were white. 39% joined the APR as a result of a paid social media advertisement. To date, the APR helped recruit for 82 studies.

CONCLUSIONS

The APR is a large, internet-based participant recruitment registry designed to raise awareness about AD prevention research and connect members with enrolling studies in their communities. It has demonstrated the ability to recruit and engage a large number of highly motivated members and assist researchers in meeting their recruitment goals. Future publications will report on the effectiveness of APR for accelerating recruitment and enrollment into AD-focused studies.

Whole-Blood Levels of MicroRNA-9 Are Decreased in Patients With Late-Onset Alzheimer Disease

Recent evidence suggests changes in circulating microRNA levels may be promising biomarkers for the clinical diagnosis of Alzheimer disease (AD). We hypothesized that whole-blood microRNAs may be useful to identify individuals with established AD. For this purpose, a sample of community-dwelling women (≥55 years old) carrying the ApoE ∊4 allele were clinically evaluated using the American Psychiatric Association/Diagnostic and Statistical Manual of Mental Disorders, Fourth edition and the Alzheimer Disease Assessment Scale-Cognitive Subscale criteria to diagnose probable AD, and the Clinical Dementia Rating scale to stage the dementia. A set of 25 mature microRNAs was rationally selected for evaluation based on experimental evidence of interaction with genes linked to the late-onset AD neuropathology. Whole-blood concentrations were determined by quantitative real-time polymerase chain reaction. Compared to patients without dementia, a median 3-fold decrease in miR-9 levels was found among patients with AD (P = .001). Our findings support blood-borne miR-9 as a candidate biomarker for probable AD, embodied by evidence from the literature of its implication in amyloidogenesis.

Neuroprotective Properties and Therapeutic Potential of Bone Marrow-Derived Microglia in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia, which is characterized by a progressive cognitive decline and senile plaques formed by amyloid β (Aβ). Microglia are the immune cells of the central nervous system (CNS). Studies have proposed 2 types of microglia, namely, the resident microglia and bone marrow-derived microglia (BMDM). Recent studies suggested that BMDM, not the resident microglia, can phagocytose Aβ, which has a great therapeutic potential in AD. Bone marrow-derived microglia can populate the CNS in an efficient manner and their functions can be regulated by some genes. Thus, methods that increase their recruitment and phagocytosis could be used as a new tool that clears Aβ and ameliorates cognitive impairment. Herein, we review the neuroprotective functions of BMDM and their therapeutic potential in AD.

The evolution of geriatric neurology

The founders of neurology in the late 19th century and early 20th century laid the foundation for modern geriatric neurology by detailed observations, in their patients, of the clinical expressions of aging of the nervous system. Further advances in clinical manifestations of aging and more detailed examination of disease states in the elderly accelerated in the last quarter of the 20th century. Basic, translational, and clinical research support of geriatric neurology studies expanded and advanced during this period and into the 21st century. The size and sophistication of this movement was stimulated by a number of factors: the successful development of geriatrics as a specialty in primary care, internal medicine, and psychiatry; the projected growth of the geriatric population; and the projections of the number of people with Alzheimer's disease. However, there were and continue to be inadequate numbers of trained geriatric neurologists available to care for the "silver tsunami" of elderly patients with age-related diseases that will present in the next 3 decades. The combination of massive investment in dementia/Alzheimer's research in the past decade, widespread awareness among researchers and trainees of the opportunities to do research in age-related diseases, and the need for further knowledge of neurodegenerative diseases led to a broad expansion of research efforts. Longitudinal clinical studies of the elderly and the advent of sophisticated neuroimaging, genetics, and laboratory techniques are advancing the field. The initiation of therapeutic interventions has led to cautious optimism about the ability to ameliorate suffering in these patients and diminish the burdens of central nervous system aging.

Cognitive Reserve from the Perspective of Preclinical Alzheimer Disease: 2020 Update

The concept of cognitive reserve (CR) was proposed to account for the discrepancy between levels of brain pathologic process or damage and clinical and cognitive function. We provide a detailed review of prospective longitudinal studies that have investigated the interaction between CR and Alzheimer disease (AD) biomarkers on clinical and cognitive outcomes among individuals with normal cognition at baseline. Current evidence is consistent with the view that higher levels of CR are associated with a delay in the onset of symptoms of mild cognitive impairment and that there may be multiple pathways by which CR exerts its protective effects.

Sex and Gender Driven Modifiers of Alzheimer's: The Role for Estrogenic Control Across Age, Race, Medical, and Lifestyle Risks

Research indicates that after advanced age, the major risk factor for late-onset Alzheimer’s disease (AD) is female sex. Out of every three AD patients, two are females with postmenopausal women contributing to over 60% of all those affected. Sex- and gender-related differences in AD have been widely researched and several emerging lines of evidence point to different vulnerabilities that contribute to dementia risk. Among those being considered, it is becoming widely accepted that gonadal steroids contribute to the gender disparity in AD, as evidenced by the “estrogen hypothesis.” This posits that sex hormones, 17β-estradiol in particular, exert a neuroprotective effect by shielding females’ brains from disease development. This theory is further supported by recent findings that the onset of menopause is associated with the emergence of AD-related brain changes in women in contrast to men of the same age. In this review, we discuss genetic, medical, societal, and lifestyle risk factors known to increase AD risk differently between the genders, with a focus on the role of hormonal changes, particularly declines in 17β-estradiol during the menopause transition (MT) as key underlying mechanisms.

Synthesis of 11C-labeled DNA polymerase-β inhibitor 5-methoxyflavone and PET/CT imaging thereof

INTRODUCTION

"Cell-cycle hypothesis" is emerging in recent years to suggest that aberrant cell cycle re-entry of differentiated neurons leads to a remarkable genetic disequilibrium which is likely to be the primary cause of neuronal apoptosis. DNA polymerase-β is involved in neuronal DNA replication during cell cycle re-entry, thus constituting a promising target for Alzheimer's disease treatment. Recently, 5-methoxyflavone was identified as a candidate molecule endowed with good biological activity and selectivity on the DNA pol-β in multiple in vitro AD models. In vivo assays, especially the brain uptake of 5-methoxyflavone, is need to be evaluated for further development for AD treatment. We report herein the synthesis of ¹¹C-labeled 5-methoxyflavone, and the evaluation of in vivo properties of 5-[¹¹C]methoxyflavone in rodents.

METHODS

The strategy for synthesis of 5-[¹¹C]methoxyflavone was developed by treating precursor 5-hydroxyflavone with [¹¹C]CH₃I and KOH in anhydrous DMF. 5-[¹¹C]Methoxyflavone was purified, then evaluated in mice by using PET/CT imaging.

RESULTS

The 5-[¹¹C]methoxyflavone was synthesized conveniently in an average decay corrected yield of 22% (n = 3) with a radiochemical purity >99%. The average molar radioactivity of 5-[¹¹C]methoxyflavone was 383 GBq/μmol. The average concentration was 0.107 μg/mL. PET/CT imaging in mice showed 5-[¹¹C]methoxyflavone rapidly passed through the blood-brain barrier with 8.36 ± 0.61%ID/g at 2 min post injection, and the radioactivity accumulation in brain was still noticeable with 2.48 ± 0.59%ID/g at 28 min post injection. The clearance rate was 3.37 (brain_{2 min}/brain_{28 min} ratio). The blood and muscle uptakes were low. The lung displayed high initial uptake and subsequent rapid clearance, while the liver and kidney displayed a relatively slow clearance. Real-time imaging showed that 5-[¹¹C]methoxyflavone accumulated immediately in the heart, then transferred to the liver and intestine, and was not observed in lower digestive tract.

CONCLUSIONS

5-[¹¹C]Methoxyflavone was synthesized conveniently in one step. The results of PET/CT imaging in C57BL/6 mice suggested 5-[¹¹C]methoxyflavone possesses appropriate pharmacokinetic properties and favorable brain uptake, thus being proved to be suitable for further development for AD treatment.

The Physical Activity and Alzheimer's Disease (PAAD) Study: Cognitive outcomes

Background

Alzheimer's disease is a progressive disease that degrades cognitive functioning and ultimately results in death. Currently, there is no cure for Alzheimer's disease and, hence, the identification of preventative strategies is important. Physical activity (PA) is a behavioral intervention that holds promise with respect to delaying the onset of Alzheimer's disease.

Purpose

The purpose of this study was to explore the differential cognitive benefits achieved in response to PA as a function of a person's genetic risk for AD.

Methods

Older cognitively normal adults (50-65 years) with a family history of AD (FHxAD) participated in an 8-month PA program. Cognitive performance was measured at baseline, pretest, midtest, and posttest and changes over time were assessed as a function of apolipoprotein E (APOE) status (carriers: 1-2 copies of the ɛ4 allele; noncarriers: 0 copies of the ɛ4 allele).

Results

Improvements in memory were associated with PA participation irrespective of APOE ɛ4 carrier status.

Conclusions

Future experimental studies are needed to confirm that PA causes improvements to cognitive performance in older cognitively normal adults with a FHxAD and that these improvements are equivalent for cognitively normal APOE ɛ4 carriers and noncarriers.

Sex Differences in Neuropsychological Test Performance in Alzheimer's Disease and the Influence of the ApoE Genotype

BACKGROUND

Only few studies exist reporting sex differences in the Alzheimer disease (AD) patients regarding cognitive profile, brain damage, and risk factors. The present study investigated the influence of sex in combination with the Alzheimer risk allele, ε4-allele of apolipoprotein E, on cognitive performance.

MATERIALS AND METHODS

We examined the effect of sex and ApoE genotype on a range of neuropsychological markers from the German version of the Consortium to Establish a Registry in Alzheimer's Disease Neuropsychological Battery in a monocentric study of 399 AD patients.

RESULTS

Male patients had significantly more years of school and occupational education compared with women. Male AD patients outperformed female patients in tasks of object naming, constructional praxis, and constructional praxis recall. There was no statistically significant interaction effect between sex and ε4-allele of apolipoprotein E for any of the examined variables.

CONCLUSIONS

The superiority of healthy men compared with women in tasks of object naming, constructional praxis, and visual memory seems to remain stable when people develop AD, indicating larger cognitive reserves in men. In contrast, findings that cognitively healthy women outperform men in tests of verbal memory and verbal fluency are not stable in AD. Further studies are needed to gain insight in the reasons for sex differences.

Process Cost Management of Alzheimer’s Disease

Summary: Determining the cost of healthcare and social care for patients is a crucial issue for many parties; therefore, both public and private payments play a decisive role in patient care. The article deals with the analysis of the possibilities of the simulation of costs related to Alzheimer’s disease. This disease is highly variable, and the cost items vary considerably. Therefore, it is necessary to use simulation methods. The results of simulation models can then be implemented in sophisticated methods working with activity costs. Findings: Models for health and social care are specific. No significant re-engineering is expected in this area, so the models must be unambiguous and easy to understand for all representatives involved. Modeling of business processes is thus a suitable means for analysis in this area. The process cost calculation is built on two simulation models. The first model is the Business Process Model and Notation (BPMN), the results of which are verified in the system dynamics model created in the stock and flow diagram. The simulations results give us appropriate values for calculating the total activity-based costs of AD. Applications: The practical part of this article deals with the identification of costs related to Alzheimer’s disease and their allocation concerning remedies. Based on this information, models for Alzheimer’s disease process cost management are developed. Results: The BPMN simulation was performed for 100 passes through a fixed-length phase process. The duration of each phase was set at 48, 108, and 40 months. Five simulations were set up, each Mini-Mental State Examination (MMSE) score set, which affected the passage through the process. Software Stella Professional was used for simulations for constant MMSE score values for the home and facility options. The values are as follows: MMSE 5 = 1331 . 26 ( 1627 . 72 ); MMSE 15 = 1202 . 72 ( 1102 . 02 ); MMSE 25 = 1051 . 24 ( 848 . 91 ). Conclusions: Both AD models created in this article produce comparable results, although each of them works on a different principle. The results are based on the selection of original data, and at the same time, these models point to the processes and subprocesses that lead to the costs. The description, specifications, and possible values of partial costs are crucial knowledge for persons in the management functions of public administration and self-government in the area of finance and management not in the field of specific diseases.

Lifestyle interventions to prevent cognitive impairment, dementia and Alzheimer disease

Research into dementia prevention is of paramount importance if the dementia epidemic is to be halted. Observational studies have identified several potentially modifiable risk factors for dementia, including hypertension, dyslipidaemia and obesity at midlife, diabetes mellitus, smoking, physical inactivity, depression and low levels of education. Randomized clinical trials are needed that investigate whether interventions targeting these risk factors can reduce the risk of cognitive decline and dementia in elderly adults, but such trials are methodologically challenging. To date, most preventive interventions have been tested in small groups, have focused on a single lifestyle factor and have yielded negative or modest results. Given the multifactorial aetiology of dementia and late-onset Alzheimer disease, multidomain interventions that target several risk factors and mechanisms simultaneously might be necessary for an optimal preventive effect. In the past few years, three large multidomain trials (FINGER, MAPT and PreDIVA) have been completed. The FINGER trial showed that a multidomain lifestyle intervention can benefit cognition in elderly people with an elevated risk of dementia. The primary results from the other trials did not show a statistically significant benefit of preventive interventions, but additional analyses among participants at risk of dementia showed beneficial effects of intervention. Overall, results from these three trials suggest that targeting of preventive interventions to at-risk individuals is an effective strategy. This Review discusses the current knowledge of lifestyle-related risk factors and results from novel trials aiming to prevent cognitive decline and dementia. Global initiatives are presented, including the World Wide FINGERS network, which aims to harmonize studies on dementia prevention, generate high-quality scientific evidence and promote its implementation.

History and progress of hypotheses and clinical trials for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory loss along with neuropsychiatric symptoms and a decline in activities of daily life. Its main pathological features are cerebral atrophy, amyloid plaques, and neurofibrillary tangles in the brains of patients. There are various descriptive hypotheses regarding the causes of AD, including the cholinergic hypothesis, amyloid hypothesis, tau propagation hypothesis, mitochondrial cascade hypothesis, calcium homeostasis hypothesis, neurovascular hypothesis, inflammatory hypothesis, metal ion hypothesis, and lymphatic system hypothesis. However, the ultimate etiology of AD remains obscure. In this review, we discuss the main hypotheses of AD and related clinical trials. Wealthy puzzles and lessons have made it possible to develop explanatory theories and identify potential strategies for therapeutic interventions for AD. The combination of hypometabolism and autophagy deficiency is likely to be a causative factor for AD. We further propose that fluoxetine, a selective serotonin reuptake inhibitor, has the potential to treat AD.

Small vessel disease to subcortical dementia: a dynamic model, which interfaces aging, cholinergic dysregulation and the neurovascular unit

BACKGROUND

Small vessels have the pivotal role for the brain's autoregulation. The arteriosclerosis-dependent alteration of the brain perfusion is one of the major determinants in small vessel disease. Endothelium distress can potentiate the flow dysregulation and lead to subcortical vascular dementia (sVAD). sVAD increases morbidity and disability. Epidemiological studies have shown that sVAD shares with cerebrovascular disease most of the common risk factors. The molecular basis of this pathology remains controversial.

PURPOSE

To detect the possible mechanisms between small vessel disease and sVAD, giving a broad vision on the topic, including pathological aspects, clinical and laboratory findings, metabolic process and cholinergic dysfunction.

METHODS

We searched MEDLINE using different search terms ("vascular dementia", "subcortical vascular dementia", "small vessel disease", "cholinergic afferents", etc). Publications were selected from the past 20 years. Searches were extended to Embase, Cochrane Library, and LILIACS databases. All searches were done from January 1, 1998 up to January 31, 2018.

RESULTS

A total of 560 studies showed up, and appropriate studies were included. Associations between traditional vascular risk factors have been isolated. We remarked that SVD and white matter abnormalities are seen frequently with aging and also that vascular and endothelium changes are related with age; the changes can be accelerated by different vascular risk factors. Vascular function changes can be heavily influenced by genetic and epigenetic factors.

CONCLUSION

Small vessel disease and the related dementia are two pathologies that deserve attention for their relevance and impact in clinical practice. Hypertension might be a historical problem for SVD and SVAD, but low pressure might be even more dangerous; CBF regional selective decrease seems to be a critical factor for small vessel disease-related dementia. In those patients, endothelium damage is a super-imposed condition. Several issues are still debatable, and more research is needed.

Evaluating the Potential of Younger Cases and Older Controls Cohorts to Improve Discovery Power in Genome-Wide Association Studies of Late-Onset Diseases

For more than a decade, genome-wide association studies have been making steady progress in discovering the causal gene variants that contribute to late-onset human diseases. Polygenic late-onset diseases in an aging population display a risk allele frequency decrease at older ages, caused by individuals with higher polygenic risk scores becoming ill proportionately earlier and bringing about a change in the distribution of risk alleles between new cases and the as-yet-unaffected population. This phenomenon is most prominent for diseases characterized by high cumulative incidence and high heritability, examples of which include Alzheimer’s disease, coronary artery disease, cerebral stroke, and type 2 diabetes, while for late-onset diseases with relatively lower prevalence and heritability, exemplified by cancers, the effect is significantly lower. In this research, computer simulations have demonstrated that genome-wide association studies of late-onset polygenic diseases showing high cumulative incidence together with high initial heritability will benefit from using the youngest possible age-matched cohorts. Moreover, rather than using age-matched cohorts, study cohorts combining the youngest possible cases with the oldest possible controls may significantly improve the discovery power of genome-wide association studies.

Trends in Memory Problems and Race/Ethnicity in the National Health and Examination Survey, 1999-2014

Background

Little data exist to describe serial population-level trends in cognitive impairment- especially among minority communities. Because memory problems are among the first warning signs of cognitive impairment, they provide a potential method for monitoring changes in cognitive health at the population level. This exploratory study aimed to: 1) estimate prevalence of memory problems among US residents by race/ethnicity, age category; and 2) examine whether racial/ethnic differences in subjective cognitive concerns (memory problems) varied across recent time periods.

Design and Setting

Serial cross-sectional analysis of self-reported data from the National Health and Examination Survey (NHANES), 1999-2014.

Participants

20,585 participants aged ≥45 years during 1999-2014, who reported race/ethnicity as non-Hispanic White (NHW), non-Hispanic Black (NHB), and Latino/Hispanic.

Measurements

The outcome of interest was subjective cognitive concerns, identified as self-reported memory problems. The frequencies of memory problems were examined for each 4-year period, across racial/ethnic groups.

Results

In adjusted analyses, compared with older (aged ≥ 65 years) NHWs, disparities in subjective cognitive concerns were observed for older Latinos for most periods (range of AOR: 1.43 - 2.01, P<.05). Additionally, Latinos without a high school education had significantly higher odds of reporting memory problems than NHW in multiple periods (range of AOR: 1.95 - 2.17, P<.005), while Latino high school graduates did not. There were no significant changes in racial/ethnic differences in subjective cognitive concerns over time.

Conclusions

The prevalence of subjective cognitive concerns across time periods points to a need to engage patients - particularly older and less-educated Latinos - about warning signs for cognitive impairment. The impact of education on subjective cognitive concerns in older Latinos may be related to acculturation and warrant further investigation.

Quantifying the Potential for Future Gene Therapy to Lower Lifetime Risk of Polygenic Late-Onset Diseases

Gene therapy techniques and genetic knowledge may sufficiently advance, within the next few decades, to support prophylactic gene therapy for the prevention of polygenic late-onset diseases. The risk of these diseases may, hypothetically, be lowered by correcting the effects of a subset of common low effect gene variants. In this paper, simulations show that if such gene therapy were to become technically possible; and if the incidences of the treated diseases follow the proportional hazards model with a multiplicative genetic architecture composed of a sufficient number of common small effect gene variants, then: (a) late-onset diseases with the highest familial heritability will have the largest number of variants available for editing; (b) diseases that currently have the highest lifetime risk, particularly those with the highest incidence rate continuing into older ages, will prove the most challenging cases in lowering lifetime risk and delaying the age of onset at a population-wide level; (c) diseases that are characterized by the lowest lifetime risk will show the strongest and longest-lasting response to such therapies; and (d) longer life expectancy is associated with a higher lifetime risk of these diseases, and this tendency, while delayed, will continue after therapy.

Quantifying the Potential for Future Gene Therapy to Lower Lifetime Risk of Polygenic Late-Onset Diseases

Gene therapy techniques and genetic knowledge may sufficiently advance, within the next few decades, to support prophylactic gene therapy for the prevention of polygenic late-onset diseases. The risk of these diseases may, hypothetically, be lowered by correcting the effects of a subset of common low effect gene variants. In this paper, simulations show that if such gene therapy were to become technically possible; and if the incidences of the treated diseases follow the proportional hazards model with a multiplicative genetic architecture composed of a sufficient number of common small effect gene variants, then: (a) late-onset diseases with the highest familial heritability will have the largest number of variants available for editing; (b) diseases that currently have the highest lifetime risk, particularly those with the highest incidence rate continuing into older ages, will prove the most challenging cases in lowering lifetime risk and delaying the age of onset at a population-wide level; (c) diseases that are characterized by the lowest lifetime risk will show the strongest and longest-lasting response to such therapies; and (d) longer life expectancy is associated with a higher lifetime risk of these diseases, and this tendency, while delayed, will continue after therapy.

Predicting progression from normal cognition to mild cognitive impairment for individuals at 5 years

Recent evidence indicates that measures from cerebrospinal fluid, MRI scans and cognitive testing obtained from cognitively normal individuals can be used to predict likelihood of progression to mild cognitive impairment several years later, for groups of individuals. However, it remains unclear whether these measures are useful for predicting likelihood of progression for an individual. The increasing focus on early intervention in clinical trials for Alzheimer's disease emphasizes the importance of improving the ability to identify which cognitively normal individuals are more likely to progress over time, thus allowing researchers to efficiently screen participants, as well as determine the efficacy of any treatment intervention. The goal of this study was to determine which measures, obtained when individuals were cognitively normal, predict on an individual basis, the onset of clinical symptoms associated with a diagnosis of mild cognitive impairment due to Alzheimer's disease. Cognitively normal participants (n = 224, mean baseline age = 57 years) were evaluated with a range of measures, including: cerebrospinal fluid amyloid-β and phosphorylated-tau, hippocampal and entorhinal cortex volume, cognitive tests scores and APOE genotype. They were then followed to determine which individuals developed mild cognitive impairment over time (mean follow-up = 11 years). The primary outcome was progression from normal cognition to the onset of clinical symptoms of mild cognitive impairment due to Alzheimer's disease at 5 years post-baseline. Time-dependent receiver operating characteristic analyses examined the sensitivity and specificity of individual measures, and combinations of measures, as predictors of the outcome. Six measures, in combination, were the most parsimonious predictors of transition to mild cognitive impairment 5 years after baseline (area under the curve = 0.85; sensitivity = 0.80, specificity = 0.75). The addition of variables from each domain significantly improved the accuracy of prediction. The incremental accuracy of prediction achieved by adding individual measures or sets of measures successively to one another was also examined, as might be done when enrolling individuals in a clinical trial. The results indicate that biomarkers obtained when individuals are cognitively normal can be used to predict which individuals are likely to develop clinical symptoms at 5 years post-baseline. As a number of the measures included in the study could also be used as subject selection criteria in a clinical trial, the findings also provide information about measures that would be useful for screening in a clinical trial aimed at individuals with preclinical Alzheimer's disease.

Age-related late-onset disease heritability patterns and implications for genome-wide association studies

Genome-wide association studies (GWASs) and other computational biology techniques are gradually discovering the causal gene variants that contribute to late-onset human diseases. After more than a decade of genome-wide association study efforts, these can account for only a fraction of the heritability implied by familial studies, the so-called "missing heritability" problem. Computer simulations of polygenic late-onset diseases (LODs) in an aging population have quantified the risk allele frequency decrease at older ages caused by individuals with higher polygenic risk scores (PRSs) becoming ill proportionately earlier. This effect is most prominent for diseases characterized by high cumulative incidence and high heritability, examples of which include Alzheimer's disease, coronary artery disease, cerebral stroke, and type 2 diabetes. The incidence rate for LODs grows exponentially for decades after early onset ages, guaranteeing that the cohorts used for GWASs overrepresent older individuals with lower PRSs, whose disease cases are disproportionately due to environmental causes such as old age itself. This mechanism explains the decline in clinical predictive power with age and the lower discovery power of familial studies of heritability and GWASs. It also explains the relatively constant-with-age heritability found for LODs of lower prevalence, exemplified by cancers.

Putative Gonadotropin-Releasing Hormone Agonist Therapy and Dementia: An Application of Medicare Hospitalization Claims Data

BACKGROUND

Estrogen and hormone replacement therapies to reduce Alzheimer's disease (AD) have yielded conflicting results. However, this study proposes that the well-characterized increase in serum gonadotropins following menopause or andropause are accountable for the increased risk of developing AD among the elderly population.

OBJECTIVE

To determine the role of gonadotropins in the development of AD and investigate gonadotropin-releasing hormone (GnRH) agonist therapy as a potential preventative and/or disease-modifying approach to AD management.

METHODS

Male Medicare beneficiaries aged 67 to 75 and hospitalized with prostate cancer (n = 115,789) were compared to three control groups: men of the same demographics undergoing a cholecystectomy (n = 97,267), herniorrhaphy (n = 68,778), or transurethral prostatectomy (n = 267,691). A proportion of the patients hospitalized with prostate cancer were assumed to have low concentrations of serum gonadotropins and sex steroids as a result of GnRH agonist therapy, while those in the control groups were assumed to have elevated gonadotropin but lowered sex steroid levels that are associated with andropause in this age group.

RESULTS

The rates of development of select diagnoses of dementia, including AD, over a twelve-year follow-up period following surgery. When compared to control patients, men hospitalized with prostate cancer have a protection against dementia after twelve years of follow-up, with relative risks ranging from 0.48 to 0.83.

CONCLUSION

Patients with prostate cancer are treated with the GnRH analogue leuprolide acetate, our data suggest that leuprolide acetate may be therapeutic for AD via its downregulation of serum gonadotropins.

Device-Embedded Cameras for Eye Tracking-Based Cognitive Assessment: Implications for Teleneuropsychology

Introduction: Widespread screening for cognitive decline is an important challenge to address as the aging population grows, but there is currently a shortage of clinical infrastructure to meet the demand for in-person evaluation. Remotely delivered assessments that utilize eye-tracking data from webcams, such as visual paired comparison (VPC) tasks, could increase access to remote, asynchronous neuropsychological screening for cognitive decline but further validation against clinical-grade eye trackers is required. Methods: To demonstrate equivalence between a novel automated scoring system for eye-tracking metrics acquired through a laptop-embedded camera and a gold-standard eye tracker, we analyzed VPC data from 18 subjects aged 50+ with normal cognitive function across three visits. The eye tracker data were scored by the manufacturer's software, and the webcam data were scored by a novel algorithm. Results: Automated scoring of webcam-based VPC data revealed strong correlations with the clinical-grade eye-tracking camera. Correlation of mean VPC performance across all time points was robust: r = 0.95 (T1 r = 0.97; T2 r = 0.88; T3 r = 0.97; p's < 0.001). Correlation of per-trial performance across time points was also robust: r = 0.88 (T1 r = 0.85; T2 r = 0.89; T3 r = 0.92; p's < 0.001). Mean differences between performance data acquired by each device were 0.00. Conclusion: These results suggest that device-embedded cameras are a valid and scalable alternative to traditional laboratory-based equipment for gaze-based tasks measuring cognitive function. The validation of this technique represents an important technical advance for the field of teleneuropsychology.