Cardiovascular risk factors and future risk of Alzheimer's disease

Predicting Alzheimer's disease from cognitive footprints in mid and late life: How much can register data and machine learning help?

BACKGROUND

Real-world data with decades-long medical records are increasingly available alongside the growing adoption of machine learning in healthcare research. We evaluated the performance of machine learning models in predicting the risk of Alzheimer's disease (AD) using data from the Finnish national registers.

METHODS

We conducted a case-control study using data from the Finnish MEDALZ (Medication use and Alzheimer's disease) study. Altogether 56,741 individuals with incident AD diagnosis (age ≥ 65 years at diagnosis and born after 1922) and their 1:1 age-, sex-, and region of residence-matched controls were included. The association of risk factors, evaluated at different age periods (45-54, 55-64, 65+), and AD were assessed with logistic regression. Predictive accuracies of logistic regressions were compared with seven machine learning models (L1-regularized logistic regression, Naive bayes, Decision tree, Random Forest, Multilayer perceptron, XGBoost, and LightGBM).

FINDINGS

63.5 % of cases and controls were females and the mean age was 79.1 (SD = 5.1). The strongest associations with AD were observed for head injuries at age 55-64 (OR, 95 % CI 1.33, 1.19-1.48) and 65+ (1.31, 1.23-1.40), followed by antidepressant use (1.30, 1.22-1.38) at 55-64 and antipsychotic use (1.27, 1.19-1.35) at 65+. The predictive accuracies of all models were low, with the best performance (AUC 0.603) observed in Random Forest for predicting AD onset at age 65-69.

INTERPRETATION

Although significant associations were identified between many risk factors and AD, the low predictive accuracies suggest that specialised healthcare diagnosis data is not sufficient for predicting AD and linkage with other data sources is needed.

Cerebral Microbleeds in Different Brain Regions and Their Associations With the Digital Clock-Drawing Test: Secondary Analysis of the Framingham Heart Study

BACKGROUND

Cerebral microbleeds (CMB) increase the risk for Alzheimer disease. Current neuroimaging methods that are used to detect CMB are costly and not always accessible.

OBJECTIVE

This study aimed to explore whether the digital clock-drawing test (DCT) may provide a behavioral indicator of CMB.

METHODS

In this study, we analyzed data from participants in the Framingham Heart Study offspring cohort who underwent both brain magnetic resonance imaging scans (Siemens 1.5T, Siemens Healthcare Private Limited; T2*-GRE weighted sequences) for CMB diagnosis and the DCT as a predictor. Additionally, paper-based clock-drawing tests were also collected during the DCT. Individuals with a history of dementia or stroke were excluded. Robust multivariable linear regression models were used to examine the association between DCT facet scores with CMB prevalence, adjusting for relevant covariates. Receiver operating characteristic (ROC) curve analyses were used to evaluate DCT facet scores as predictors of CMB prevalence. Sensitivity analyses were conducted by further including participants with stroke and dementia.

RESULTS

The study sample consisted of 1020 (n=585, 57.35% female) individuals aged 45 years and older (mean 72, SD 7.9 years). Among them, 64 (6.27%) participants exhibited CMB, comprising 46 with lobar-only, 11 with deep-only, and 7 with mixed (lobar+deep) CMB. Individuals with CMB tended to be older and had a higher prevalence of mild cognitive impairment and higher white matter hyperintensities compared to those without CMB (P<.05). While CMB were not associated with the paper-based clock-drawing test, participants with CMB had a lower overall DCT score (CMB: mean 68, SD 23 vs non-CMB: mean 76, SD 20; P=.009) in the univariate comparison. In the robust multiple regression model adjusted for covariates, deep CMB were significantly associated with lower scores on the drawing efficiency (β=-0.65, 95% CI -1.15 to -0.15; P=.01) and simple motor (β=-0.86, 95% CI -1.43 to -0.30; P=.003) domains of the command DCT. In the ROC curve analysis, DCT facets discriminated between no CMB and the CMB subtypes. The area under the ROC curve was 0.76 (95% CI 0.69-0.83) for lobar CMB, 0.88 (95% CI 0.78-0.98) for deep CMB, and 0.98 (95% CI 0.96-1.00) for mixed CMB, where the area under the ROC curve value nearing 1 indicated an accurate model.

CONCLUSIONS

The study indicates a significant association between CMB, especially deep and mixed types, and reduced performance in drawing efficiency and motor skills as assessed by the DCT. This highlights the potential of the DCT for early detection of CMB and their subtypes, providing a reliable alternative for cognitive assessment and making it a valuable tool for primary care screening before neuroimaging referral.

Dysregulation of Lipid Metabolism Serves as A Link Between Alzheimer's and Cardiovascular Disease, As Witnessed in A Cross-Sectional Study

Cardiovascular risk factors and established cardiovascular disease (CVD) increase the risk of suffering dementia of the Alzheimer's type (DAT). Here, we set out to define specific molecular profiles of CVD in patients with DAT to better understand its relationship, to unravel the mechanisms underlying the high risk of developing DAT in CVD patients and to define new markers of early disease. Plasma samples from patients with DAT, with and without CVD, were analyzed through a multiomics approach, with integration of metabolomics and proteomics datasets using the OmicsNet web-based tool. Metabolomics results showed an enrichment in lipids and lipid-like molecules. Similarly, the most significant cluster identified through proteomics was formed by 5 proteins related to lipoprotein and cholesterol metabolism. After integration and functional enrichment, glycerolipid metabolism, fatty acid degradation and sphingolipid metabolism were among the most significant functions. Finally, differential expression of ABCA1 and APOH proteins was verified, in an independent cohort also including controls and patients with CVD alone. Both proteins positively correlated with phospho-Tau (181), a classical hallmark of DAT. Different molecular profiles exist in patients with DAT, with and without CVD, with exacerbated alterations in patients in which DAT and CVD co-exist. This information may help to define biomarkers like ABCA1 and APOH that identify patients with cardiovascular dysfunction that are at high risk of developing DAT. Such markers will allow more personalized interventions to be selected, a further step towards precision medicine for individuals whose molecular profiles indicate a distinct response to the same management strategies.

Causal relationship between Alzheimer's disease and unstable angina: a bidirectional Mendelian randomization analysis

Background

Research from observational studies has demonstrated a link between Alzheimer's disease (AD) and a higher risk of cardiovascular disease (CVD). Uncertainty surrounds the exact genetic cause of AD and coronary heart disease, particularly unstable angina (UA). Mendelian randomization (MR) analysis was used to examine the causal genetic link between AD and UA to evaluate the impact of AD on UA.

Methods

The purpose of the bidirectional MR analysis was to investigate the link between exposure and illness causation. Genetic instrumental variables for AD were obtained from European populations using genome-wide association studies (GWAS). The primary causal conclusions were obtained using the inverse variance weighted approach (IVW), and other sensitivity analysis techniques were employed. Sensitivity analyses were carried out to evaluate heterogeneity and horizontal pleiotropy to guarantee accurate MR results.

Results

An elevated risk of UA was linked to genetically predicted AD (IVW: OR=3.439, 95% CI: 1.565-7.555, P=0.002). A substantial genetic relationship between UA and the risk of AD was not supported by any evidence in the reverse study (IVW: OR=0.998, 95% CI: 0.995-1.001, P=0.190). Various MR techniques produced consistent results. Sensitivity analysis revealed no discernible heterogeneity or horizontal pleiotropy.

Conclusions

One risk factor for UA that we found in our bidirectional Mendelian randomization trial was AD. This highlights the necessity of researching the underlying molecular mechanisms linked to AD and UA as well as the possibility of creating individualized treatment plans based on genetic data.

Prescription medication use in the 10 years prior to diagnosis of young onset Alzheimer's disease: a nationwide nested case-control study

BACKGROUND

Patients with young onset Alzheimer's disease (YOAD) face long diagnostic delays. Prescription medication use may provide insights into early signs and symptoms, which may help facilitate timely diagnosis.

METHODS

In a register-based nested case-control study, we examined medication use for everyone diagnosed with YOAD in a Danish memory clinic during 2016-2020 compared to cognitively healthy controls. Prescription medication use were grouped into 13 overall categories (alimentary tract and metabolism, blood and blood forming organs, cardiovascular system, dermatologicals, genitourinary system and sex hormones, systemic hormonal preparations, antiinfectives for systemic use, antineoplastic and immunomodulating agents, musculo-skeletal system, nervous system, antiparasitic products, respiratory system, and sensory organs). Further stratifications were done for predetermined subcategories with a use-prevalence of at least 5% in the study population. Conditional logistic regression produced odds ratios, which given the use of incidence-density matching is interpretable as incidence rate ratios (IRRs). The association between prescription medication use and subsequent YOAD diagnosis was examined in the entire 10-year study period and in three time-intervals.

RESULTS

The study included 1745 YOAD cases and 5235 controls. In the main analysis, several overall categories showed significant associations with YOAD in one or more time-intervals, namely blood and blood forming organs and nervous system. Prescription medication use in the nervous system category was increased for YOAD cases compared to controls already 10->5 years prior to diagnosis (IRR 1.17, 95% CI 1.05-1.31), increasing to 1.57 (95% CI 1.39-1.78) in the year preceding diagnosis. This was largely driven by antidepressant and antipsychotic use, and especially prominent for first-time users.

CONCLUSIONS

In this study, medication use in several categories was associated with YOAD. Onset of treatment-requiring psychiatric symptoms such as depression or psychosis in mid-life may serve as potential early indicators of YOAD.

Superagers Resist Typical Age-Related White Matter Structural Changes

Superagers are elderly individuals with the memory ability of people 30 years younger and provide evidence that age-related cognitive decline is not inevitable. In a sample of 64 superagers (mean age, 81.9; 59% women) and 55 typical older adults (mean age, 82.4; 64% women) from the Vallecas Project, we studied, cross-sectionally and longitudinally over 5 years with yearly follow-ups, the global cerebral white matter status as well as region-specific white matter microstructure assessment derived from diffusivity measures. Superagers and typical older adults showed no difference in global white matter health (total white matter volume, Fazekas score, and lesions volume) cross-sectionally or longitudinally. However, analyses of diffusion parameters revealed the better white matter microstructure in superagers than in typical older adults. Cross-sectional differences showed higher fractional anisotropy (FA) in superagers mostly in frontal fibers and lower mean diffusivity (MD) in most white matter tracts, expressed as an anteroposterior gradient with greater group differences in anterior tracts. FA decrease over time is slower in superagers than in typical older adults in all white matter tracts assessed, which is mirrored by MD increases over time being slower in superagers than in typical older adults in all white matter tracts except for the corticospinal tract, the uncinate fasciculus, and the forceps minor. The better preservation of white matter microstructure in superagers relative to typical older adults supports resistance to age-related brain structural changes as a mechanism underpinning the remarkable memory capacity of superagers, while their regional aging pattern is in line with the last-in-first-out hypothesis.

Alzheimer's disease and drug delivery across the blood-brain barrier: approaches and challenges

Alzheimer's disease (AD) is a diverse disease with a complex pathophysiology. The presence of extracellular β-amyloid deposition as neuritic plaques and intracellular accumulation of hyper-phosphorylated tau as neurofibrillary tangles remain the core neuropathologic criteria for diagnosing Alzheimer's disease. Nonetheless, several recent basic discoveries have revealed significant pathogenic roles for other essential cellular and molecular processes. Previously, there were not so many disease-modifying medications (DMT) available as drug distribution through the blood-brain barrier (BBB) is difficult due to its nature, especially drugs of polypeptides nature and proteins. Recently FDA has approved lecanemab as DMT for its proven efficacy. It is also complicated to deliver drugs for diseases like epilepsy or any brain tumor due to the limitations of the BBB. After the advancements in the drug delivery system, different techniques are used to transport the medication across the BBB. Other methods are used, like enhancement of brain blood vessel fluidity by liposomes, infusion of hyperosmotic solutions, and local intracerebral implants, but these are invasive approaches. Non-invasive approaches include the formulation of nanoparticles and their coating with polymers. This review article emphasizes all the above-mentioned techniques, procedures, and challenges to transporting medicines across the BBB. It summarizes the most recent literature dealing with drug delivery across the BBB.

Neurofilament Light Chain as a Biomarker of Global Cognition in Individuals With Possible Vascular Mild Cognitive Impairment

BACKGROUND

Neurofilament Light Chain (NfL) is a biomarker of axonal injury elevated in mild cognitive impairment (MCI) and Alzheimer's disease dementia. Blood NfL also inversely correlates with cognitive performance in those conditions. However, few studies have assessed NfL as a biomarker of global cognition in individuals demonstrating mild cognitive deficits who are at risk for vascular-related cognitive decline.

OBJECTIVE

To assess the relationship between blood NfL and global cognition in individuals with possible vascular MCI (vMCI) throughout cardiac rehabilitation (CR). Additionally, NfL levels were compared to age/sex-matched cognitively unimpaired (CU) controls.

METHOD

Participants with coronary artery disease (vMCI or CU) were recruited at entry to a 24-week CR program. Global cognition was measured using the Montreal Cognitive Assessment (MoCA) and plasma NfL level (pg/ml) was quantified using a highly sensitive enzyme-linked immunosorbent assay.

RESULTS

Higher plasma NfL was correlated with worse MoCA scores at baseline (β = -.352, P = .029) in 43 individuals with vMCI after adjusting for age, sex, and education. An increase in NfL was associated with worse global cognition (b[SE] = -4.81[2.06], P = .023) over time, however baseline NfL did not predict a decline in global cognition. NfL levels did not differ between the vMCI (n = 39) and CU (n = 39) groups (F(1, 76) = 1.37, P = .245).

CONCLUSION

Plasma NfL correlates with global cognition at baseline in individuals with vMCI, and is associated with decline in global cognition during CR. Our findings increase understanding of NfL and neurobiological mechanisms associated with cognitive decline in vMCI.

Impaired Remodeling of White Adipose Tissue in Obesity and Aging: From Defective Adipogenesis to Adipose Organ Dysfunction

The adipose organ adapts and responds to internal and environmental stimuli by remodeling both its cellular and extracellular components. Under conditions of energy surplus, the subcutaneous white adipose tissue (WAT) is capable of expanding through the enlargement of existing adipocytes (hypertrophy), followed by de novo adipogenesis (hyperplasia), which is impaired in hypertrophic obesity. However, an impaired hyperplastic response may result from various defects in adipogenesis, leading to different WAT features and metabolic consequences, as discussed here by reviewing the results of the studies in animal models with either overexpression or knockdown of the main molecular regulators of the two steps of the adipogenesis process. Moreover, impaired WAT remodeling with aging has been associated with various age-related conditions and reduced lifespan expectancy. Here, we delve into the latest advancements in comprehending the molecular and cellular processes underlying age-related changes in WAT function, their involvement in common aging pathologies, and their potential as therapeutic targets to influence both the health of elderly people and longevity. Overall, this review aims to encourage research on the mechanisms of WAT maladaptation common to conditions of both excessive and insufficient fat tissue. The goal is to devise adipocyte-targeted therapies that are effective against both obesity- and age-related disorders.

The association of glucose metabolism measures and diabetes status with Alzheimer's disease biomarkers of amyloid and tau: A systematic review and meta-analysis

Conflicting evidence exists on the relationship between diabetes mellitus (DM) and Alzheimer's disease (AD) biomarkers. Therefore, we conducted a random-effects meta-analysis to evaluate the correlation of glucose metabolism measures (glycated hemoglobin, fasting blood glucose, insulin resistance indices) and DM status with AD biomarkers of amyloid-β and tau measured by positron emission tomography or cerebrospinal fluid. We selected 37 studies from PubMed and Embase, including 11,694 individuals. More impaired glucose metabolism and DM status were associated with higher tau biomarkers (r=0.11[0.03-0.18], p=0.008; I2=68%), but were not associated with amyloid-β biomarkers (r=-0.06[-0.13-0.01], p=0.08; I2=81%). Meta-regression revealed that glucose metabolism and DM were specifically associated with tau biomarkers in population settings (p=0.001). Furthermore, more impaired glucose metabolism and DM status were associated with lower amyloid-β biomarkers in memory clinic settings (p=0.004), and in studies with a higher prevalence of dementia (p<0.001) or lower cognitive scores (p=0.04). These findings indicate that DM is associated with biomarkers of tau but not with amyloid-β. This knowledge is valuable for improving dementia and DM diagnostics and treatment.

Physical Activity Moderates the Relationship between Cardiovascular Disease Risk Burden and Cognition in Older Adults

INTRODUCTION

Older individuals with a higher cardiovascular disease (CVD) burden have a higher risk for accelerated cognitive decline and dementia. Physical activity (PA) is an inexpensive and accessible preventive measure to CVD, cognitive impairment, and dementia. The current study examined (1) whether PA moderates the relationship between CVD burden and cognition and (2) whether the moderating effect of PA differs by race/ethnicity groups and by APOE-ɛ4 status.

METHODS

Our cross-sectional study included participants from the Washington Heights-Inwood Columbia Aging Project (WHICAP), a multiethnic, community-based, longitudinal study on aging and dementia among individuals aged 65 years and older who reside in northern Manhattan. All participants underwent an interview and a neuropsychological assessment for global cognition, memory, language, visuospatial, and speed functioning.

RESULTS

In 2,122 older individuals without dementia, having a higher CVD burden was associated with worse cognitive scores for global, language, speed, and visuospatial cognitive functions. PA mitigated the relationship between CVD burden and visuospatial function. Furthermore, PA mitigated the association of CVD burden with global cognition, language, and visuospatial functions in APOE-ɛ4 carriers but not in non-carriers.

DISCUSSION/CONCLUSION

Our study suggests that PA may mitigate the negative association between CVD and cognition, especially in APOE-ɛ4 carriers. The moderating effect of PA did not differ by race/ethnicity.

Sex matters in the association between cardiovascular health and incident dementia: evidence from real world data

BACKGROUND

Cardiovascular health has been associated with dementia onset, but little is known about the variation of such association by sex and age considering dementia subtypes. We assessed the role of sex and age in the association between cardiovascular risk and the onset of all-cause dementia, Alzheimer's disease, and vascular dementia in people aged 50-74 years.

METHODS

This is a retrospective cohort study covering 922.973 Catalans who attended the primary care services of the Catalan Health Institute (Spain). Data were obtained from the System for the Development of Research in Primary Care (SIDIAP database). Exposure was the cardiovascular risk (CVR) at baseline categorized into four levels of Framingham-REGICOR score (FRS): low (FRS < 5%), low-intermediate (5% ≤ FRS < 7.5%), high-intermediate (7.5% ≤ FRS < 10%), high (FRS ≥ 10%), and one group with previous vascular disease. Cases of all-cause dementia and Alzheimer's disease were identified using validated algorithms, and cases of vascular dementia were identified by diagnostic codes. We fitted stratified Cox models using age parametrized as b-Spline.

RESULTS

A total of 51,454 incident cases of all-cause dementia were recorded over a mean follow-up of 12.7 years. The hazard ratios in the low-intermediate and high FRS groups were 1.12 (95% confidence interval: 1.08-1.15) and 1.55 (1.50-1.60) for all-cause dementia; 1.07 (1.03-1.11) and 1.17 (1.11-1.24) for Alzheimer's disease; and 1.34 (1.21-1.50) and 1.90 (1.67-2.16) for vascular dementia. These associations were stronger in women and in midlife compared to later life in all dementia types. Women with a high Framingham-REGICOR score presented a similar risk of developing dementia - of any type - to women who had previous vascular disease, and at age 50-55, they showed three times higher risk of developing dementia risk compared to the lowest Framingham-REGICOR group.

CONCLUSIONS

We found a dose‒response association between the Framingham-REGICOR score and the onset of all dementia types. Poor cardiovascular health in midlife increased the onset of all dementia types later in life, especially in women.

Impact of micronutrients and nutraceuticals on cognitive function and performance in Alzheimer's disease

Alzheimer's disease (AD) is a major global health problem today and is the most common form of dementia. AD is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary clusters, leading to decreased brain acetylcholine levels in the brain. Another mechanism underlying the pathogenesis of AD is the abnormal phosphorylation of tau protein that accumulates at the level of neurofibrillary aggregates, and the areas most affected by this pathological process are usually the cholinergic neurons in cortical, subcortical, and hippocampal areas. These effects result in decreased cognitive function, brain atrophy, and neuronal death. Malnutrition and weight loss are the most frequent manifestations of AD, and these are also associated with greater cognitive decline. Several studies have confirmed that a balanced low-calorie diet and proper nutritional intake may be considered important factors in counteracting or slowing the progression of AD, whereas a high-fat or hypercholesterolemic diet predisposes to an increased risk of developing AD. Especially, fruits, vegetables, antioxidants, vitamins, polyunsaturated fatty acids, and micronutrients supplementation exert positive effects on aging-related changes in the brain due to their antioxidant, anti-inflammatory, and radical scavenging properties. The purpose of this review is to summarize some possible nutritional factors that may contribute to the progression or prevention of AD, understand the role that nutrition plays in the formation of Aβ plaques typical of this neurodegenerative disease, to identify some potential therapeutic strategies that may involve some natural compounds, in delaying the progression of the disease.

Adipose tissue as a therapeutic target for vascular damage in Alzheimer's disease

Adipose tissue has recently been recognized as an important endocrine organ that plays a crucial role in energy metabolism and in the immune response in many metabolic tissues. With this regard, emerging evidence indicates that an important crosstalk exists between the adipose tissue and the brain. However, the contribution of adipose tissue to the development of age-related diseases, including Alzheimer's disease, remains poorly defined. New studies suggest that the adipose tissue modulates brain function through a range of endogenous biologically active factors known as adipokines, which can cross the blood-brain barrier to reach the target areas in the brain or to regulate the function of the blood-brain barrier. In this review, we discuss the effects of several adipokines on the physiology of the blood-brain barrier, their contribution to the development of Alzheimer's disease and their therapeutic potential. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Polyvascular atherosclerosis and renal dysfunction increase the odds of cognitive impairment in vascular disease: findings of the LipidCardio study

INTRODUCTION

Growing evidence suggests a causal role for atherosclerotic vascular disease in cognitive impairment and dementia. Atherosclerosis may present as monovascular disease (monoVD) or as widespread polyvascular atherosclerotic disease (polyVD). Evidence on the relationship between monoVD or polyVD and cognitive impairment is limited.

METHODS

We conducted a cross-sectional analysis of baseline data from the LipidCardio Study. The main outcome measure was the presence of cognitive impairment, defined as a Mini-Mental State Examination (MMSE) score < 26.

RESULTS

The mean age was 71.5 years, 30.3% were female, 17.3% had no evidence of large-vessel atherosclerosis, 71.1% had monoVD, and 11.7% had polyVD, defined as the presence of atherosclerosis in ≥ 2 vascular territories (coronary, cerebral, aortic, or lower extremity). A total of 21.6% had cognitive impairment according to the prespecified cutoff (MMSE < 26). Overall, the odds of cognitive impairment increased for each additional vascular territory affected by atherosclerosis [adjusted odds ratio 1.76, 95% confidence interval (CI) 1.21-2.57, p = 0.003]. Furthermore, there was evidence for an interaction between vascular disease and chronic kidney disease (CKD). The odds of cognitive impairment were not greater in the monoVD subgroup compared to those without any atherosclerosis, if CKD was absent (OR 0.98, 95% CI 0.48-2.10; p = 0.095), while the odds ratio (OR) of cognitive impairment with polyVD compared to no atherosclerosis was 2.71 (95% CI 1.10-6.92; p = 0.031). In contrast, in patients with CKD, both monoVD and polyVD were associated with significantly higher odds of cognitive impairment than no atherosclerosis.

CONCLUSIONS

PolyVD is associated with increased odds of cognitive impairment. MonoVD is associated with cognitive impairment only in the presence of CKD.

Sex-dependent association of serum uric acid levels with amyloid accumulation among amyloid-positive older adults

We aimed to examine the potential effect of sex on the longitudinal association of baseline serum uric acid levels with brain amyloid accumulation over time among older adults with and without abnormal amyloid. At baseline, the study sample comprised 499 older adults, including 276 men and 223 women. Linear mixed-effects regression models were fitted to estimate the individual slopes of change in brain amyloid accumulation [as measured by AV45 standardized uptake value ratio (SUVR)] over time. At baseline, we did not observe a relationship between serum uric acid levels and brain amyloid deposition in women or men regardless of amyloid status. Among amyloid negative subjects, women and men did not differ in the relationship between baseline serum uric acid and the annual change in amyloid accumulation in subjects with normal amyloid levels. In amyloid positive women, serum uric acid levels were not associated with the annual change in amyloid accumulation (unstandardized β = 0.0005, SE = 0.0006, p value = 0.4179). However, in amyloid positive men, serum uric acid levels were negatively associated with the annual change in amyloid accumulation (unstandardized β = -0.0015, SE = 0.0005, p value = 0.0048). These findings support a potential sex-specific effect on the relationship between serum uric acid levels and amyloid accumulation among amyloid positive older adults.

Important roles of linoleic acid and α-linolenic acid in regulating cognitive impairment and neuropsychiatric issues in metabolic-related dementia

Metabolic syndrome (MetS), which is characterized by insulin resistance, high blood glucose, obesity, and dyslipidemia, is known to increase the risk of dementia accompanied by memory loss and depression. The direct pathways and specific mechanisms in the central nervous system (CNS) for addressing fatty acid imbalances in MetS have not yet been fully elucidated. Among polyunsaturated acids, linoleic acid (LA, n6-PUFA) and α-linolenic acid (ALA, n3-PUFA), which are two essential fatty acids that should be provided by food sources (e.g., vegetable oils and seeds), have been reported to regulate various cellular mechanisms including apoptosis, inflammatory responses, mitochondrial biogenesis, and insulin signaling. Furthermore, inadequate intake of LA and ALA is reported to be involved in neuropathology and neuropsychiatric diseases as well as imbalanced metabolic conditions. Herein, we review the roles of LA and ALA on metabolic-related dementia focusing on insulin resistance, dyslipidemia, synaptic plasticity, cognitive function, and neuropsychiatric issues. This review suggests that LA and ALA are important fatty acids for concurrent treatment of both MetS and neurological problems.

Alzheimer's Disease in Lebanon: Exploring Genetic and Environmental Risk Factors-A Comprehensive Review

Alzheimer's disease (AD) is a neurodegenerative condition that displays a high prevalence in Lebanon causing a local burden in healthcare and socio-economic sectors. Unfortunately, the lack of prevalence studies and clinical trials in Lebanon minimizes the improvement of AD patient health status. In this review, we include over 155 articles to cover the different aspects of AD ranging from mechanisms to possible treatment and management tools. We highlight some important modifiable and non-modifiable risk factors of the disease including genetics, age, cardiovascular diseases, smoking, etc. Finally, we propose a hypothetical genetic synergy model between APOE4 and TREM2 genes which constitutes a potential early diagnostic tool that helps in reducing the risk of AD based on preventative measures decades before cognitive decline. The studies on AD in Lebanon and the Middle East are scarce. This review points out the importance of genetic mapping in the understanding of disease pathology which is crucial for the emergence of novel diagnostic tools. Hence, we establish a rigid basis for further research to identify the most influential genetic and environmental risk factors for the purpose of using more specific diagnostic tools and possibly adopting a local management protocol.

Diabetic Retinopathy and Brain Structure, Cognition Function, and Dementia: A Bidirectional Mendelian Randomization Study

BACKGROUND

Accumulating evidence has demonstrated that hyperglycemia is a possible risk factor for mild cognitive impairment or Alzheimer's disease. Diabetic retinopathy (DR) has been identified as a risk factor for dementia in patients with diabetes.

OBJECTIVE

This study aimed to investigate the causal relationships between DR and brain structure, cognitive function, and dementia.

METHODS

We performed bidirectional two-sample Mendelian randomization for DR, brain structure, cognitive function, and dementia using the inverse-variance weighted method.

RESULTS

Inverse-variance weighted analysis showed the association of DR with vascular dementia (OR = 1.68, 95% CI: 1.01-2.82), and dementia was significantly associated with the increased risk of non-proliferative DR (NPDR) (OR = 1.76, 95% CI: 1.04-2.98). Furthermore, better cognitive performance was significantly associated with a reduced risk of NPDR (OR = 0.85, 95% CI: 0.74-0.98). No association was observed between DR and brain structure.

CONCLUSIONS

These findings suggest that the association of DR with vascular dementia. The reciprocal effect of cognitive performance and dementia on NPDR risk highlights the potential benefits of dementia prevention for reducing the burden of DR.

Sex and Sleep Disruption as Contributing Factors in Alzheimer's Disease

Alzheimer's disease (AD) affects more women than men, with women throughout the menopausal transition potentially being the most under researched and at-risk group. Sleep disruptions, which are an established risk factor for AD, increase in prevalence with normal aging and are exacerbated in women during menopause. Sex differences showing more disrupted sleep patterns and increased AD pathology in women and female animal models have been established in literature, with much emphasis placed on loss of circulating gonadal hormones with age. Interestingly, increases in gonadotropins such as follicle stimulating hormone are emerging to be a major contributor to AD pathogenesis and may also play a role in sleep disruption, perhaps in combination with other lesser studied hormones. Several sleep influencing regions of the brain appear to be affected early in AD progression and some may exhibit sexual dimorphisms that may contribute to increased sleep disruptions in women with age. Additionally, some of the most common sleep disorders, as well as multiple health conditions that impair sleep quality, are more prevalent and more severe in women. These conditions are often comorbid with AD and have bi-directional relationships that contribute synergistically to cognitive decline and neuropathology. The association during aging of increased sleep disruption and sleep disorders, dramatic hormonal changes during and after menopause, and increased AD pathology may be interacting and contributing factors that lead to the increased number of women living with AD.

A review on nonviral, nonbacterial infectious agents toxicity involved in neurodegenerative diseases

Neuronal death, decreased activity or dysfunction of neurotransmitters are some of the pathophysiological reasons for neurodegenerative diseases like Alzheimer's, Parkinson's and multiple sclerosis. Also, there is evidence for the role of infections and infectious agents in neurodegenerative diseases and the effect of some metabolites in microorganisms in the pathophysiology of these diseases. In this study, we intend to evaluate the existing studies on the role of infectious agents and their metabolites on the pathophysiology of neurodegenerative diseases. PubMed, Scopus, Google Scholar and Web of Science search engines were searched. Some infectious agents have been observed in neurodegenerative diseases. Also, isolations of some fungi and microalgae have an improving effect on Parkinson's and Alzheimer's.

Blood-Brain Barrier Breakdown in Alzheimer's Disease: Mechanisms and Targeted Strategies

The blood-brain barrier (BBB) is a unique and selective feature of the central nervous system's vasculature. BBB dysfunction has been observed as an early sign of Alzheimer's Disease (AD) before the onset of dementia or neurodegeneration. The intricate relationship between the BBB and the pathogenesis of AD, especially in the context of neurovascular coupling and the overlap of pathophysiology in neurodegenerative and cerebrovascular diseases, underscores the urgency to understand the BBB's role more deeply. Preserving or restoring the BBB function emerges as a potentially promising strategy for mitigating the progression and severity of AD. Molecular and genetic changes, such as the isoform ε4 of apolipoprotein E (ApoEε4), a significant genetic risk factor and a promoter of the BBB dysfunction, have been shown to mediate the BBB disruption. Additionally, receptors and transporters like the low-density lipoprotein receptor-related protein 1 (LRP1), P-glycoprotein (P-gp), and the receptor for advanced glycation end products (RAGEs) have been implicated in AD's pathogenesis. In this comprehensive review, we endeavor to shed light on the intricate pathogenic and therapeutic connections between AD and the BBB. We also delve into the latest developments and pioneering strategies targeting the BBB for therapeutic interventions, addressing its potential as a barrier and a carrier. By providing an integrative perspective, we anticipate paving the way for future research and treatments focused on exploiting the BBB's role in AD pathogenesis and therapy.

Association between Coronary Heart Disease, Heart Failure, and Risk of Alzheimer's Disease: A Systematic Review and Meta-Analysis

Background

Cardiovascular diseases such as coronary heart disease (CHD), heart failure (HF), and stroke have been linked to the development of Alzheimer's disease (AD). However, previous studies have reported inconsistent results. The study aimed to investigate the association between CHD, HF, and the risk of AD using a meta-analysis.

Methods

STATA 12.0 software is used to compute odds ratios (ORs)/relative risks (RRs) and 95% confidence intervals (CIs) for the association between CHD, HF, and the risk of AD.

Results

A total of 12 studies (including N = 36,913 individuals with AD and N = 1,701,718 participants) investigated the association between CHD and the risk of AD. Meta-analysis indicated that CHD was associated with an increased risk of AD with a random effects model (OR/RR: 1.22, 95% CI: 1.00-1.48, I2 = 97.2%, P < 0.001). Additionally, seven studies (including N = 5,119 individuals with AD and N = 1,231,399 participants) investigated the association between myocardial infarction (MI) and the risk of AD. Our meta-analysis demonstrated no significant association between MI and the risk of AD with a fixed effects model (RR: 1.09, 95% CI: 0.91-1.30, I2 = 42.8%, P = 0.105). Finally, six studies (including N = 83,065 individuals with AD and N = 2,414,963 participants) examined the association between HF and the risk of AD. Our meta-analysis revealed that HF was associated with an increased risk of AD using a random effects model (RR: 1.53, 95% CI: 1.05-2.24, I2 = 96.8%, P < 0.001).

Conclusion

In conclusion, our meta-analysis suggests that CHD and HF are associated with an increased risk of developing AD. Nonetheless, more large-scale prospective studies are necessary to further investigate the associations between CHD, HF, and the risk of AD.

Dementia risk in patients with heart disease and depression

The high prevalence of Alzheimer's disease and dementia is a growing concern for healthcare systems and patients.

Objective

The primary objective of our study was to assess the association of depression and heart disease on the risk of dementias like Alzheimer's disease or vascular dementia in patients.

Methods

This retrospective study used electronic health records data that was provided by the HealthVerity™ Marketplace. The characteristics of the patient population were recorded and the risk of dementia was examined using adjusted logistic regression models.

Results

The analysis included 49,735 participants and revealed that patients who have heart disease or depression had a higher risk of dementia. Patients who had both heart disease and depression were over three times more likely to have dementia and Alzheimer's disease, and over five times more likely to have vascular dementia compared to patients who only have a diagnosis of heart disease. Depression was associated with a fourfold increase in the risk of dementia. Participants with a diagnosis of most types of heart disease as well as depression had increased risk for developing dementia.

Conclusion

This study revealed that patients with both heart disease and depression had increased odds of having dementia as well as vascular dementia and Alzheimer's disease. These findings may serve to support policies and healthcare decision-making to increase preventive measures for dementia and Alzheimer's disease among patients with both depression and heart disease.

Advanced photon counting CT imaging pipeline for cardiac phenotyping of apolipoprotein E mouse models

BACKGROUND

Cardiovascular disease (CVD) is associated with the apolipoprotein E (APOE) gene and lipid metabolism. This study aimed to develop an imaging-based pipeline to comprehensively assess cardiac structure and function in mouse models expressing different APOE genotypes using photon-counting computed tomography (PCCT).

METHODS

123 mice grouped based on APOE genotype (APOE2, APOE3, APOE4, APOE knockout (KO)), gender, human NOS2 factor, and diet (control or high fat) were used in this study. The pipeline included PCCT imaging on a custom-built system with contrast-enhanced in vivo imaging and intrinsic cardiac gating, spectral and temporal iterative reconstruction, spectral decomposition, and deep learning cardiac segmentation. Statistical analysis evaluated genotype, diet, sex, and body weight effects on cardiac measurements.

RESULTS

Our results showed that PCCT offered high quality imaging with reduced noise. Material decomposition enabled separation of calcified plaques from iodine enhanced blood in APOE KO mice. Deep learning-based segmentation showed good performance with Dice scores of 0.91 for CT-based segmentation and 0.89 for iodine map-based segmentation. Genotype-specific differences were observed in left ventricular volumes, heart rate, stroke volume, ejection fraction, and cardiac index. Statistically significant differences were found between control and high fat diets for APOE2 and APOE4 genotypes in heart rate and stroke volume. Sex and weight were also significant predictors of cardiac measurements. The inclusion of the human NOS2 gene modulated these effects.

CONCLUSIONS

This study demonstrates the potential of PCCT in assessing cardiac structure and function in mouse models of CVD which can help in understanding the interplay between genetic factors, diet, and cardiovascular health.

Age and sex differences in the association between APOE genotype and Alzheimer's disease in a Taiwan Chinese population

Introduction

The Apolipoprotein E (APOE) epsilon (ε) 4 allele is a well-established risk factor for late-onset Alzheimer's disease (AD). Reports on white ancestry populations have showed that age, sex, and ethnicity have different effects on the association between APOE genotype and AD. However, studies on Asian populations such as Taiwan Chinese populations are limited. This study aimed to evaluate the association between APOE genotype and AD in a Taiwan Chinese population, and to explore if the association varies by age and sex.

Methods

We conducted a case-control study in 725 patients with AD and 1,067 age- and sex- matched controls without dementia from a Taiwan Chinese population. Logistic regression models were used to test the association between AD and APOE genotypes. Secondary analyses considered age (<75 or ≥75 years old), and sex stratified models.

Results

The risk of AD was significantly increased for people with at least one copy of APOE ε4 (OR = 2.52, 95% CI = 2.01-3.17, p < 0.001) and in a dose-dependent manner. Our results did not show an statistically significance different in AD risk when women and men carrying APOEε4 were compared. Despite not reaching statistical significance, the risk of APOE ε4 for AD was higher among younger participants (OR = 3.21, 95% CI = 2.26-4.56, p < 0.001) compared to older ones (OR = 2.13, 95% CI = 1.53-2.97, p < 0.001). When considering both sex and age, the risk of AD was higher among older men carrying APOE ε4 (OR = 2.64, 95% CI = 1.51-4.60 in men; OR = 1.90, 95% CI = 1.26-2.86 in women), while women carrying APOE ε4 appeared to have an increased risk at a younger age (OR = 3.29, 95% CI = 2.20-4.93 in women; OR = 2.91, 95% CI = 1.40-6.05 in men).

Discussion

The APOE ε4 allele represents a major risk factor for AD in the Taiwanese population. The effect of APOE ε4 allele on AD risk appeared to be stronger among men aged 75 years or more and among younger women.

Intersectionality in Alzheimer's Disease: The Role of Female Sex and Black American Race in the Development and Prevalence of Alzheimer's Disease

It is well known that vascular factors and specific social determinants of health contribute to dementia risk and that the prevalence of these risk factors differs according to race and sex. In this review, we discuss the intersection of sex and race, particularly female sex and Black American race. Women, particularly Black women, have been underrepresented in Alzheimer's disease clinical trials and research. However, in recent years, the number of women participating in clinical research has steadily increased. A greater prevalence of vascular risk factors such as hypertension and type 2 diabetes, coupled with unique social and environmental pressures, puts Black American women particularly at risk for the development of Alzheimer's disease and related dementias. Female sex hormones and the use of hormonal birth control may offer some protective benefits, but results are mixed, and studies do not consistently report the demographics of their samples. We argue that as a research community, greater efforts should be made to not only recruit this vulnerable population, but also report the demographic makeup of samples in research to better target those at greatest risk for the disease.

Body mass index and two-year change of in vivo Alzheimer's disease pathologies in cognitively normal older adults

BACKGROUND

Low body mass index (BMI) or underweight status in late life is associated with an increased risk of dementia or Alzheimer's disease (AD). However, the relationship between late-life BMI and prospective longitudinal changes of in-vivo AD pathology has not been investigated.

METHODS

This prospective longitudinal study was conducted as part of the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer's Disease (KBASE). A total of 194 cognitive normal older adults were included in the analysis. BMI at baseline was measured, and two-year changes in brain Aβ and tau deposition on PET imaging were used as the main outcomes. Linear mixed-effects (LME) models were used to examine the relationships between late-life BMI and longitudinal change in AD neuropathological biomarkers.

RESULTS

A lower BMI at baseline was significantly associated with a greater increase in tau deposition in AD-signature region over 2 years (β, -0.018; 95% CI, -0.028 to -0.004; p = .008), In contrast, BMI was not related to two-year changes in global Aβ deposition (β, 0.0002; 95% CI, -0.003 to 0.002, p = .671). An additional exploratory analysis for each sex showed lower baseline BMI was associated with greater increases in tau deposition in males (β, -0.027; 95% CI, -0.046 to -0.009; p = 0.007), but not in females.

DISCUSSION

The findings suggest that lower BMI in late-life may predict or contribute to the progression of tau pathology over the subsequent years in cognitively unimpaired older adults.

Soluble and insoluble protein aggregates, endoplasmic reticulum stress, and vascular dysfunction in Alzheimer's disease and cardiovascular diseases

Dementia refers to a particular group of symptoms characterized by difficulties with memory, language, problem-solving, and other thinking skills that affect a person's ability to perform everyday activities. Alzheimer's disease (AD) is the most common form of dementia, affecting about 6.2 million Americans aged 65 years and older. Likewise, cardiovascular diseases (CVDs) are a major cause of disability and premature death, impacting 126.9 million adults in the USA, a number that increases with age. Consequently, CVDs and cardiovascular risk factors are associated with an increased risk of AD and cognitive impairment. They share important age-related cardiometabolic and lifestyle risk factors, that make them among the leading causes of death. Additionally, there are several premises and hypotheses about the mechanisms underlying the association between AD and CVD. Although AD and CVD may be considered deleterious to health, the study of their combination constitutes a clinical challenge, and investigations to understand the mechanistic pathways for the cause-effect and/or shared pathology between these two disease constellations remains an active area of research. AD pathology is propagated by the amyloid β (Aβ) peptides. These peptides give rise to small, toxic, and soluble Aβ oligomers (SPOs) that are nonfibrillar, and it is their levels that show a robust correlation with the extent of cognitive impairment. This review will elucidate the interplay between the effects of accumulating SPOs in AD and CVDs, the resulting ER stress response, and their role in vascular dysfunction. We will also address the potential underlying mechanisms, including the possibility that SPOs are among the causes of vascular injury in CVD associated with cognitive decline. By revealing common mechanistic underpinnings of AD and CVD, we hope that novel experimental therapeutics can be designed to reduce the burden of these devastating diseases. Graphical abstract Alzheimer's disease (AD) pathology leads to the release of Aβ peptides, and their accumulation in the peripheral organs has varying effects on various components of the cardiovascular system including endoplasmic reticulum (ER) stress and vascular damage. Image created with BioRender.com.

Elevated plasma sulfides are associated with cognitive dysfunction and brain atrophy in human Alzheimer's disease and related dementias

Emerging evidence indicates that vascular stress is an important contributor to the pathophysiology of Alzheimer's disease and related dementias (ADRD). Hydrogen sulfide (H2S) and its metabolites (acid-labile (e.g., iron-sulfur clusters) and bound (e.g., per-, poly-) sulfides) have been shown to modulate both vascular and neuronal homeostasis. We recently reported that elevated plasma sulfides were associated with cognitive dysfunction and measures of microvascular disease in ADRD. Here we extend our previous work to show associations between elevated sulfides and magnetic resonance-based metrics of brain atrophy and white matter integrity. Elevated bound sulfides were associated with decreased grey matter volume, while increased acid labile sulfides were associated with decreased white matter integrity and greater ventricular volume. These findings are consistent with alterations in sulfide metabolism in ADRD which may represent maladaptive responses to oxidative stress.

Vascular contributions to Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia and is characterized by progressive neurodegeneration and cognitive decline. Understanding the pathophysiology underlying AD is paramount for the management of individuals at risk of and suffering from AD. The vascular hypothesis stipulates a relationship between cardiovascular disease and AD-related changes although the nature of this relationship remains unknown. In this review, we discuss several potential pathological pathways of vascular involvement in AD that have been described including dysregulation of neurovascular coupling, disruption of the blood brain barrier, and reduced clearance of metabolite waste such as beta-amyloid, a toxic peptide considered the hallmark of AD. We will also discuss the two-hit hypothesis which proposes a 2-step positive feedback loop in which microvascular insults precede the accumulation of Aß and are thought to be at the origin of the disease development. At neuroimaging, signs of vascular dysfunction such as chronic cerebral hypoperfusion have been demonstrated, appearing early in AD, even before cognitive decline and alteration of traditional biomarkers. Cerebral small vessel disease such as cerebral amyloid angiopathy, characterized by the aggregation of Aß in the vessel wall, is highly prevalent in vascular dementia and AD patients. Current data is unclear whether cardiovascular disease causes, precipitates, amplifies, precedes, or simply coincides with AD. Targeted imaging tools to quantitatively evaluate the intracranial vasculature and longitudinal studies in individuals at risk for or in the early stages of the AD continuum could be critical in disentangling this complex relationship between vascular disease and AD.

Cognitive effects of cilostazol in Alzheimer's dementia patients with peripheral arterial occlusive disease: A case-control study

AIM

Alzheimer's dementia (AD) is a slowly progressing neurodegenerative disease, characterized by beta-amyloid deposition and neurofibrillary tangles. Peripheral atherosclerosis may deteriorate these processes via endothelial cell dysfunction and microvascular impairment. Cilostazol - a phosphodiesterase 3 inhibitor - is a standard treatment for peripheral arterial occlusive disease and a potential treatment for preserving cognitive function in AD patients. We aimed to determine whether cilostazol is beneficial in AD patients with peripheral arterial occlusive disease by evaluating Cognitive Abilities Screening Instrument (CASI) domains.

METHODS

We conducted a retrospective case-control study of 62 AD patients in Taiwan. Thirty-one patients had peripheral arterial occlusive disease and were receiving cilostazol plus acetylcholinesterase inhibitors (AchEIs) or N-methyl d-aspartate antagonists, whereas 31 others were receiving AchEIs. Therapeutic responses were measured using neuropsychological assessments. The CASI was administered at baseline and 12 months later; different domains were analyzed between the groups using univariate and multivariate analyses.

RESULTS

Age, sex, education duration, ApoE ε4 gene status, and initial Mini-Mental State Examination scores were not different between the two groups. Except for fluency, no CASI domains showed a statistical difference between the groups. A significant difference was observed in category fluency (P = 0.010). In the logistic regression analysis, after adjusting for covariate effects, category fluency still showed a significant difference between the groups (P = 0.013).

CONCLUSIONS

In AD patients with peripheral arterial occlusive disease who have received Food and Drug Administration-approved pharmacotherapy, cilostazol, as an antiplatelet, may help to preserve general cognitive function, with significant preservation in category fluency. Geriatr Gerontol Int 2023; 23: 194-199.

Metabolic Syndrome as a Risk Factor for Alzheimer's Disease: A Focus on Insulin Resistance

Alzheimer's disease (AD) is the main type of dementia and is a disease with a profound socioeconomic burden due to the lack of effective treatment. In addition to genetics and environmental factors, AD is highly associated with metabolic syndrome, defined as the combination of hypertension, hyperlipidemia, obesity and type 2 diabetes mellitus (T2DM). Among these risk factors, the connection between AD and T2DM has been deeply studied. It has been suggested that the mechanism linking both conditions is insulin resistance. Insulin is an important hormone that regulates not only peripheral energy homeostasis but also brain functions, such as cognition. Insulin desensitization, therefore, could impact normal brain function increasing the risk of developing neurodegenerative disorders in later life. Paradoxically, it has been demonstrated that decreased neuronal insulin signalling can also have a protective role in aging and protein-aggregation-associated diseases, as is the case in AD. This controversy is fed by studies focused on neuronal insulin signalling. However, the role of insulin action on other brain cell types, such as astrocytes, is still unexplored. Therefore, it is worthwhile exploring the involvement of the astrocytic insulin receptor in cognition, as well as in the onset and/or development of AD.

The small HDL particle hypothesis of Alzheimer's disease

We propose the hypothesis that small high-density lipoprotein (HDL) particles reduce the risk of Alzheimer's disease (AD) by virtue of their capacity to exchange lipids, affecting neuronal membrane composition and vascular and synaptic functions. Concentrations of small HDLs in cerebrospinal fluid (CSF) and plasma were measured in 180 individuals ≥60 years of age using ion mobility methodology. Small HDL concentrations in CSF were positively associated with performance in three domains of cognitive function independent of apolipoprotein E (APOE) ε4 status, age, sex, and years of education. Moreover, there was a significant correlation between levels of small HDLs in CSF and plasma. Further studies will be aimed at determining whether specific components of small HDL exchange across the blood, brain, and CSF barriers, and developing approaches to exploit small HDLs for therapeutic purposes.

Bioinformatic analysis of biological pathways in coronary heart disease and Alzheimer’s disease

Aim. Using bioinformatic tools, to perform a pathway enrichment analysis in Alzheimer’s disease and coronary heart disease (CHD).

Materials and methods. Genes contributing to susceptibility to CHD and Alzheimer’s disease were obtained from the public database DisGeNET (Database of Gene – Disease Associations). A pathway enrichment analysis was performed in the ClueGO Cytoscape plug-in (version 3.6.0) using hypergeometric distribution and the KEGG and Reactome databases.

Results. The identified genes contributing to susceptibility to Alzheimer’s disease and CHD are included in 69 common signaling pathways, grouped into the following subgroups: cell death signaling pathways (1); signaling pathways regulating immune responses (2); signaling pathways responsible for fatty acid metabolism (3); signaling pathways involved in the functioning of the nervous system (4), cardiovascular system (5), and endocrine system (6).

Conclusion. Following the performed analysis, we identified possible associations between processes involving genetic factors and their products in CHD and Alzheimer’s disease. In particular, we assumed that susceptibility genes involved in the implementation of these pathways regulate apoptosis, production of inflammatory cytokines and chemokines, lipid metabolism, β-amyloid formation, and angiogenesis.

Insulin resistance in Alzheimer's disease: The genetics and metabolomics links

Alzheimer's disease (AD) is a neurodegenerative disease with significant socioeconomic burden worldwide. Although genetics and environmental factors play a role, AD is highly associated with insulin resistance (IR) disorders such as metabolic syndrome (MS), obesity, and type two diabetes mellitus (T2DM). These findings highlight a shared pathogenesis. The use of metabolomics as a downstream systems' biology (omics) approach can help to identify these shared metabolic traits and assist in the early identification of at-risk groups and potentially guide therapy. Targeting the shared AD-IR metabolic trait with lifestyle interventions and pharmacological treatments may offer promising AD therapeutic approach. In this narrative review, we reviewed the literature on the AD-IR pathogenic link, the shared genetics and metabolomics biomarkers between AD and IR disorders, as well as the lifestyle interventions and pharmacological treatments which target this pathogenic link.

Comorbidities Incorporated to Improve Prediction for Prevalent Mild Cognitive Impairment and Alzheimer's Disease in the HABS-HD Study

BACKGROUND

Blood biomarkers have the potential to transform Alzheimer's disease (AD) diagnosis and monitoring, yet their integration with common medical comorbidities remains insufficiently explored.

OBJECTIVE

This study aims to enhance blood biomarkers' sensitivity, specificity, and predictive performance by incorporating comorbidities. We assess this integration's efficacy in diagnostic classification using machine learning, hypothesizing that it can identify a confident set of predictive features.

METHODS

We analyzed data from 1,705 participants in the Health and Aging Brain Study-Health Disparities, including 116 AD patients, 261 with mild cognitive impairment, and 1,328 cognitively normal controls. Blood samples were assayed using electrochemiluminescence and single molecule array technology, alongside comorbidity data gathered through clinical interviews and medical records. We visually explored blood biomarker and comorbidity characteristics, developed a Feature Importance and SVM-based Leave-One-Out Recursive Feature Elimination (FI-SVM-RFE-LOO) method to optimize feature selection, and compared four models: Biomarker Only, Comorbidity Only, Biomarker and Comorbidity, and Feature-Selected Biomarker and Comorbidity.

RESULTS

The combination model incorporating 17 blood biomarkers and 12 comorbidity variables outperformed single-modal models, with NPV12 at 92.78%, AUC at 67.59%, and Sensitivity at 65.70%. Feature selection led to 22 chosen features, resulting in the highest performance, with NPV12 at 93.76%, AUC at 69.22%, and Sensitivity at 70.69%. Additionally, interpretative machine learning highlighted factors contributing to improved prediction performance.

CONCLUSIONS

In conclusion, combining feature-selected biomarkers and comorbidities enhances prediction performance, while feature selection optimizes their integration. These findings hold promise for understanding AD pathophysiology and advancing preventive treatments.

Risk Factors for Dementia in Patients With Incident Rheumatoid Arthritis: A Population-Based Cohort Study

OBJECTIVE

Growing evidence suggests that patients with rheumatoid arthritis (RA) have increased risk for dementia. We assessed risk factors for incident dementia in an inception cohort of patients with RA.

METHODS

This retrospective population-based cohort study included residents of 8 counties in Minnesota who were ≥ 50 years of age when they met 1987 American College of Rheumatology criteria for incident RA between 1980 and 2014 and were followed until death/migration or December 31, 2019. Patients with dementia before RA incidence were excluded. Incident dementia was defined as 2 relevant International Classification of Diseases, 9th or 10th revision codes at least 30 days apart. Data on sociodemographics, disease characteristics, cardiovascular/cerebrovascular disease (CVD) risk factors, and comorbidities were abstracted from medical records.

RESULTS

The study included 886 patients with RA (mean age 65.1 yrs, 65.2% female). During the follow-up period (median 8.5 yrs), 103 patients developed dementia. After adjusting for age, sex, and calendar year of RA incidence, older age at RA incidence (HR 1.14 per 1 year increase, 95% CI 1.12-1.17), rheumatoid nodules (HR 1.76, 95% CI 1.05-2.95), hypertension (HR 1.84, 95% CI 1.19-2.85), presence of large joint swelling (HR 2.03, 95% CI 1.14-3.60), any CVD (HR 2.25, 95% CI 1.38-3.66), particularly ischemic stroke (HR 3.16, 95% CI 1.84-5.43) and heart failure (HR 1.82, 95% CI 1.10-3.00), anxiety (HR 1.86, 95% CI 1.16-2.97), and depression (HR 2.63, 95% CI 1.76-3.93) were associated with increased risk of dementia. After adjusting for CVD risk factors and any CVD, all covariates listed above were still significantly associated with risk of dementia.

CONCLUSION

Apart from age, hypertension, depression, and anxiety, all of which are universally recognized risk factors for dementia, clinically active RA and presence of CVD were associated with an elevated risk of dementia incidence among patients with RA.

Incretin and insulin signaling as novel therapeutic targets for Alzheimer's and Parkinson's disease

Despite an ever-growing prevalence and increasing economic burden of Alzheimer's disease (AD) and Parkinson's disease (PD), recent advances in drug development have only resulted in minimally effective treatment. In AD, along with amyloid and tau phosphorylation, there is an associated increase in inflammation/glial activation, a decrease in synaptic function, an increase in astrocyte activation, and a state of insulin resistance. In PD, along with α-synuclein accumulation, there is associated inflammation, synaptic dysfunction, dopaminergic neuronal loss, and some data to suggest insulin resistance. Therapeutic strategies for neurodegenerative disorders have commonly targeted individual pathological processes. An effective treatment might require either utilization of multiple drugs which target the individual pathological processes which underlie the neurodegenerative disease or the use of a single agent which could influence multiple pathological processes. Insulin and incretins are compounds with multiple effects on neurodegenerative processes. Preclinical studies have demonstrated that GLP-1 receptor agonists reduce neuroinflammation, reduce tau phosphorylation, reduce amyloid deposition, increase synaptic function, and improve memory formation. Incretin mimetics may act through the restoration of insulin signaling pathways, inducing further neuroprotective effects. Currently, phase 2 and phase 3 trials are underway in AD and PD populations. Here, we provide a comprehensive review of the therapeutic potential of incretin mimetics and insulin in AD and PD.

Cardiovascular Risk Factors and Risk of Alzheimer Disease and Mortality: A Latent Class Approach

Background Cardiovascular risk factors co-occur with one another, and little is known about the extent of their clustering and risk of Alzheimer disease (AD). We identify groups of cardiovascular risk factors in cognitively normal individuals and investigate between-group differences in incident AD and death. Methods and Results Cognitively normal individuals were recruited from the National Alzheimer's Coordinator Center. A latent class analysis was conducted with hypertension, hypercholesterolemia, heart condition, stroke, smoking history, diabetes, and high body mass index. Between-group differences in the incidence of AD, mortality, and mortality-adjusted AD were investigated. This study included 12 412 cognitively normal individuals (average follow-up, 65 months). Three groups were identified: (1) low probabilities of cardiovascular risk factors (reference; N=5398 [43%]), (2) hypertension and hypercholesterolemia (vascular-dominant; N=5721 [46%]), and (3) hypertension, hypercholesterolemia, diabetes, and high body mass index (vascular-metabolic; N=1293 [10%]). Both vascular groups were significantly older, had more men, were slightly less educated, and were slightly more cognitively impaired than the reference group (all P<0.05). However, only the vascular-metabolic group had a significantly younger age of death compared with the reference group (84.3 versus 88.7 years, P<0.001). Only the vascular-dominant group had a greater incidence of AD (odds ratio [OR], 1.30; P<0.001) compared with the reference group. Mortality was greater in the vascular-dominant (OR, 3.26; P<0.001) and vascular-metabolic groups (OR, 1.84; P=0.02). Mortality-adjusted AD was greater in the vascular-dominant (OR, 1.54; P=0.02) and vascular-metabolic groups (OR, 1.46; P=0.04). Conclusions Three distinct cardiovascular risk factor groups were identified in cognitively normal elderly individuals. Only the vascular-dominant group was associated with a greater incidence of AD. Selective mortality may contribute to the attenuated association between the vascular-metabolic group and incident AD.

Metabolomic profiles predict individual multidisease outcomes

Risk stratification is critical for the early identification of high-risk individuals and disease prevention. Here we explored the potential of nuclear magnetic resonance (NMR) spectroscopy-derived metabolomic profiles to inform on multidisease risk beyond conventional clinical predictors for the onset of 24 common conditions, including metabolic, vascular, respiratory, musculoskeletal and neurological diseases and cancers. Specifically, we trained a neural network to learn disease-specific metabolomic states from 168 circulating metabolic markers measured in 117,981 participants with ~1.4 million person-years of follow-up from the UK Biobank and validated the model in four independent cohorts. We found metabolomic states to be associated with incident event rates in all the investigated conditions, except breast cancer. For 10-year outcome prediction for 15 endpoints, with and without established metabolic contribution, a combination of age and sex and the metabolomic state equaled or outperformed established predictors. Moreover, metabolomic state added predictive information over comprehensive clinical variables for eight common diseases, including type 2 diabetes, dementia and heart failure. Decision curve analyses showed that predictive improvements translated into clinical utility for a wide range of potential decision thresholds. Taken together, our study demonstrates both the potential and limitations of NMR-derived metabolomic profiles as a multidisease assay to inform on the risk of many common diseases simultaneously.

Influence of genetic and cardiometabolic risk factors in Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder. Cardiometabolic and genetic risk factors play an important role in the trajectory of AD. Cardiometabolic risk factors including diabetes, mid-life obesity, mid-life hypertension and elevated cholesterol have been linked with cognitive decline in AD subjects. These potential risk factors associated with cerebral metabolic changes which fuel AD pathogenesis have been suggested to be the reason for the disappointing clinical trial results. In appreciation of the risks involved, using search engines such as PubMed, Scopus, MEDLINE and Google Scholar, a relevant literature search on cardiometabolic and genetic risk factors in AD was conducted. We discuss the role of genetic as well as established cardiovascular risk factors in the neuropathology of AD. Moreover, we show new evidence of genetic interaction between several genes potentially involved in different pathways related to both neurodegenerative process and cardiovascular damage.

A healthy mind in a healthy body: Effects of arteriosclerosis and other risk factors on cognitive aging and dementia

In this review we start from the assumption that, to fully understand cognitive aging, it is important to embrace a holistic view, integrating changes in bodily, brain, and cognitive functions. This broad view can help explain individual differences in aging trajectories and could ultimately enable prevention and remediation strategies. As the title of this review suggests, we claim that there are not only indirect but also direct effects of various organ systems on the brain, creating cascades of phenomena that strongly contribute to age-related cognitive decline. Here we focus primarily on the cerebrovascular system, because of its direct effects on brain health and close connections with the development and progression of Alzheimer's Disease and other types of dementia. We start by reviewing the main cognitive changes that are often observed in normally aging older adults, as well as the brain systems that support them. Second, we provide a brief overview of the cerebrovascular system and its known effects on brain anatomy and function, with a focus on aging. Third, we review genetic and lifestyle risk factors that may affect the cerebrovascular system and ultimately contribute to cognitive decline. Lastly, we discuss this evidence, review limitations, and point out avenues for additional research and clinical intervention.

Safety and efficacy of plasma transfusion from exercise-trained donors in patients with early Alzheimer's disease: protocol for the ExPlas study

INTRODUCTION

Given that exercise training reduces the risk of developing Alzheimer's disease (AD), induces changes in the blood composition and has widespread systemic benefits, it is reasonable to hypothesise that exercised plasma (ExPlas) may have rejuvenative properties. The main objective is to test safety and tolerability of transfusing ExPlas from young, healthy, fit adults to patients with mild cognitive impairment (MCI) or early AD. The study is a pilot for a future efficacy study. The key secondary objectives are examining the effect of plasma transfusions on cognitive function, fitness level, vascular risk profile, assessment of cerebral blood flow and hippocampal volume, quality of life, functional connectivity assessed by resting state functional MRI and biomarkers in blood and cerebrospinal fluid.

METHODS AND ANALYSIS

ExPlas is a double-blinded, randomised controlled clinical single-centre trial. Patients up to 75 years of age with diagnosis early symptomatic phase AD will be recruited from two Norwegian hospitals. ExPlas is plasma drawn by plasmapheresis once a month for 4 months, from a total of 30 fit male donors (aged 18-40, BMI≤27 kg/m² and maximal oxygen uptake>55 mL/kg/min). All units will be virus inactivated by the Intercept method in accordance with procedures at St. Olavs University Hospital. Comparison with isotonic saline allows differentiation from a non-blood product. The main study consists of 6 rounds of examinations in addition to 12 plasma transfusions divided over three 4-week periods during study year-1. It is also planned to conduct follow-up examinations 2 and 5 years after baseline ETHICS AND DISSEMINATION: Written informed consent will be obtained from all participants and participation is voluntary. All participants have a next of kin who will follow them throughout the study to represent the patient's interest. The study is approved by the Regional Committee for Medical and Health Research Ethics (REK 2018/702) and the Norwegian Medicines Agency (EudraCT No. 2018-000148-24). The study will be published in an open access journal and results will be presented at numerous national and international meetings as well as on social media platforms.

TRIAL REGISTRATION NUMBER

EudraCT No. 2018-000148-24.

CLINICALTRIALS

gov, NCT05068830.

Edible folic acid and medicinal folinic acid produce cardioprotective effects in late-stage triple-transgenic Alzheimer's disease model mice by suppressing cardiac hypertrophy and fibrosis

Some clinical studies have indicated the patients with Alzheimer's disease (AD) display an increased risk of cardiovascular disease (CVD). Here, to examine the relationship between AD and CVDs, we investigated the changes in heart function in triple-transgenic late-stage AD model mice (3× Tg-AD; APPSwe, PS1M146V, and tauP301L). We fed the AD mice folic acid (FA) or folinic acid (FN) and analyzed the protective effects of the compounds on the heart; specifically, 20-month-old triple-transgenic AD mice, weighing 34-55 g, were randomly allocated into three groups-the AD, AD + FA, and AD + FN groups-and subject to gastric feeding with FA or FN once daily at 12 mg/kg body weight (BW) for 3 months. Mouse BWs were assessed throughout the trial, at the end of which the animals were sacrificed using carbon dioxide suffocation. We found that BW, whole-heart weight, and left-ventricle weight were reduced in the AD + FA and AD + FN groups as compared with the measurements in the AD group. Furthermore, western blotting of excised heart tissue revealed that the levels of the hypertrophy-related protein markers phospho(p)-p38 and p-c-Jun were markedly decreased in the AD + FA group, whereas p-GATA4, and ANP were strongly reduced in the AD + FN group. Moreover, the fibrosis-related proteins uPA, MMP-2, MEK1/2 and SP-1 were decreased in the heart in both AD + FN group. In summary, our results indicate that FA and FN can exert anti-cardiac hypertrophy and fibrosis effects to protect the heart in aged triple-transgenic AD model mice, particular in FN.

Horizons in Human Aging Neuroscience: From Normal Neural Aging to Mental (Fr)Agility

While aging is an important risk factor for neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, age-related cognitive decline can also manifest without apparent neurodegenerative changes. In this review, we discuss molecular, cellular, and network changes that occur during normal aging in the absence of neurodegenerative disease. Emerging findings reveal that these changes include metabolic alterations, oxidative stress, DNA damage, inflammation, calcium dyshomeostasis, and several other hallmarks of age-related neural changes that do not act on their own, but are often interconnected and together may underlie age-related alterations in brain plasticity and cognitive function. Importantly, age-related cognitive decline may not be reduced to a single neurobiological cause, but should instead be considered in terms of a densely connected system that underlies age-related cognitive alterations. We speculate that a decline in one hallmark of neural aging may trigger a decline in other, otherwise thus far stable subsystems, thereby triggering a cascade that may at some point also incur a decline of cognitive functions and mental well-being. Beyond studying the effects of these factors in isolation, considerable insight may be gained by studying the larger picture that entails a representative collection of such factors and their interactions, ranging from molecules to neural networks. Finally, we discuss some potential interventions that may help to prevent these alterations, thereby reducing cognitive decline and mental fragility, and enhancing mental well-being, and healthy aging.

B Lymphocytes in Alzheimer's Disease-A Comprehensive Review

Alzheimer's disease (AD) represents the most common type of neurodegenerative dementia and is characterized by extracellular amyloid-β (Aβ) deposition, pathologic intracellular tau protein tangles, and neuronal loss. Increasing evidence has been accumulating over the past years, supporting a pivotal role of inflammation in the pathogenesis of AD. Microglia, monocytes, astrocytes, and neurons have been shown to play a major role in AD-associated inflammation. However recent studies showed that the role of both T and B lymphocytes may be important. In particular, B lymphocytes are the cornerstone of humoral immunity, they constitute a heterogenous population of immune cells, being their mature subsets significantly impacted by the inflammatory milieu. The role of B lymphocytes on AD pathogenesis is gaining interest for several reasons. Indeed, the majority of elderly people develop the process of "inflammaging", which is characterized by increased blood levels of proinflammatory molecules associated with an elevated susceptibility to chronic diseases. Epitope-specific alteration pattern of naturally occurring antibodies targeting the amino-terminus and the mid-domain of Aβ in both plasma and cerebrospinal fluid has been described in AD patients. Moreover, a possible therapeutic role of B lymphocytes depletion was recently demonstrated in murine AD models. Interestingly, active immunization against Aβ and tau, one of the main therapeutic strategies under investigation, depend on B lymphocytes. Finally. several molecules being tested in AD clinical trials can modify the homeostasis of B cells. This review summarizes the evidence supporting the role of B lymphocytes in AD from the pathogenesis to the possible therapeutic implications.

Alzheimer's Disease Connected Genes in the Post-Ischemic Hippocampus and Temporal Cortex

It is considered that brain ischemia can be causative connected to Alzheimer’s disease. In the CA1 and CA3 regions of the hippocampus and temporal cortex, genes related to Alzheimer’s disease, such as the amyloid protein precursor (APP), β-secretase (BACE1), presenilin 1 (PSEN1) and 2 (PSEN2), are deregulated by ischemia. The pattern of change in the CA1 area of the hippocampus covers all genes tested, and the changes occur at all post-ischemic times. In contrast, the pattern of gene changes in the CA3 subfield is much less intense, does not occur at all post-ischemic times, and is delayed in time post-ischemia relative to the CA1 field. Conversely, the pattern of gene alterations in the temporal cortex appears immediately after ischemia, and does not occur at all post-ischemic times and does not affect all genes. Evidence therefore suggests that various forms of dysregulation of the APP, BACE1 and PSEN1 and PSEN2 genes are associated with individual neuronal cell responses in the CA1 and CA3 areas of the hippocampus and temporal cortex with reversible cerebral ischemia. Scientific data indicate that an ischemic episode of the brain is a trigger of amyloidogenic processes. From the information provided, it appears that post-ischemic brain injury additionally activates neuronal death in the hippocampus and temporal cortex in an amyloid-dependent manner.