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

Potential role of tanycyte-derived neurogenesis in Alzheimer's disease

Tanycytes, specialized ependymal cells located in the hypothalamus, play a crucial role in the generation of new neurons that contribute to the neural circuits responsible for regulating the systemic energy balance. The precise coordination of the gene networks controlling neurogenesis in naive and mature tanycytes is essential for maintaining homeostasis in adulthood. However, our understanding of the molecular mechanisms and signaling pathways that govern the proliferation and differentiation of tanycytes into neurons remains limited. This article aims to review the recent advancements in research into the mechanisms and functions of tanycyte-derived neurogenesis. Studies employing lineage-tracing techniques have revealed that the neurogenesis specifically originating from tanycytes in the hypothalamus has a compensatory role in neuronal loss and helps maintain energy homeostasis during metabolic diseases. Intriguingly, metabolic disorders are considered early biomarkers of Alzheimer's disease. Furthermore, the neurogenic potential of tanycytes and the state of newborn neurons derived from tanycytes heavily depend on the maintenance of mild microenvironments, which may be disrupted in Alzheimer's disease due to the impaired blood-brain barrier function. However, the specific alterations and regulatory mechanisms governing tanycyte-derived neurogenesis in Alzheimer's disease remain unclear. Accumulating evidence suggests that tanycyte-derived neurogenesis might be impaired in Alzheimer's disease, exacerbating neurodegeneration. Confirming this hypothesis, however, poses a challenge because of the lack of long-term tracing and nucleus-specific analyses of newborn neurons in the hypothalamus of patients with Alzheimer's disease. Further research into the molecular mechanisms underlying tanycyte-derived neurogenesis holds promise for identifying small molecules capable of restoring tanycyte proliferation in neurodegenerative diseases. This line of investigation could provide valuable insights into potential therapeutic strategies for Alzheimer's disease and related conditions.

Decoding microglial immunometabolism: a new frontier in Alzheimer's disease research

Alzheimer's disease (AD) involves a dynamic interaction between neuroinflammation and metabolic dysregulation, where microglia play a central role. These immune cells undergo metabolic reprogramming in response to AD-related pathology, with key genes such as TREM2, APOE, and HIF-1α orchestrating these processes. Microglial metabolism adapts to environmental stimuli, shifting between oxidative phosphorylation and glycolysis. Hexokinase-2 facilitates glycolytic flux, while AMPK acts as an energy sensor, coordinating lipid and glucose metabolism. TREM2 and APOE regulate microglial lipid homeostasis, influencing Aβ clearance and immune responses. LPL and ABCA7, both associated with AD risk, modulate lipid processing and cholesterol transport, linking lipid metabolism to neurodegeneration. PPARG further supports lipid metabolism by regulating microglial inflammatory responses. Amino acid metabolism also contributes to microglial function. Indoleamine 2,3-dioxygenase controls the kynurenine pathway, producing neurotoxic metabolites linked to AD pathology. Additionally, glucose-6-phosphate dehydrogenase regulates the pentose phosphate pathway, maintaining redox balance and immune activation. Dysregulated glucose and lipid metabolism, influenced by genetic variants such as APOE4, impair microglial responses and exacerbate AD progression. Recent findings highlight the interplay between metabolic regulators like REV-ERBα, which modulates lipid metabolism and inflammation, and Syk, which influences immune responses and Aβ clearance. These insights offer promising therapeutic targets, including strategies aimed at HIF-1α modulation, which could restore microglial function depending on disease stage. By integrating metabolic, immune, and genetic factors, this review underscores the importance of microglial immunometabolism in AD. Targeting key metabolic pathways could provide novel therapeutic strategies for mitigating neuroinflammation and restoring microglial function, ultimately paving the way for innovative treatments in neurodegenerative diseases.

Understanding the link between insulin resistance and cognition: a cross-sectional study conducted in an urban, South Indian cohort

BACKGROUND

Recent research suggests that metabolic dysregulation caused by insulin resistance (IR) can have a negative impact on cognition. Therefore, the objective of this study is to explore the role of IR as an independent metabolic risk for decreased cognitive performance.

METHODS

The study included 1072 non-demented participants aged 45 years and above were recruited from Tata Longitudinal Study of Aging (TLSA). Fasting insulin and blood glucose levels were collected during the baseline visit. HOMA-IR formula was used to calculate IR. Cognition was assessed using the COGNITO neuropsychological test battery. Generalized Linear Regression Model (GLM) was performed to find the relationship between IR category and COGNITO battery. The brain imaging was conducted using a 3 Tesla MRI system. The cortical volumes were acquired using Freesurfer software (v7.2.0) (Salgado et al. Arq Gastroenterol 47(2):165-169, 2010). Further, GLM analysis was performed for MRI variables.

RESULTS

The estimated general prevalence of IR in our study is 56.3%. Model 1 suggested that IR is associated with reduced auditory attention (p = 0.014), and word comprehension (p = 0.043) tasks. Model 2 and 4 showed that there is an association with IR and poorerauditory attention (p = 0.015; p = 0.012) task. However, there was no significant association found in model 3. GLM analysis for MRI indicated that IR is associated with reduced brain volumes in left hemisphere like amygdala (p = 0.0012), inferior temporal lobe (p = 0.002), lateral orbitofrontal cortex (p = 0.005), superior temporal insula (p = 0.017), middle temporal lobe (p = 0.002), entorhinal (p = 0.049), and right hemisphere brain volumes like precuneus (p = 0.025), and insula (p = 0.002).

CONCLUSIONS

Our study findings conclude IR is significantly associated with poorer cognitive performance related to auditory attention. Furthermore, the study also revealed that IR is associated with decreased brain volumes in specific regions.

Revealing Lingonberry's Neuroprotective Potential in Alzheimer's Disease Through Network Pharmacology and Molecular Docking

Alzheimer's disease is a progressive neurodegenerative disorder with limited treatment options. Lingonberry (Vaccinium vitis-idaea L.) has demonstrated neuroprotective and anti-inflammatory properties, yet the underlying mechanisms remain unclear. This study employed network pharmacology, molecular docking, and molecular dynamics simulations to explore the therapeutic potential in Alzheimer's disease. Pathway analysis identified monoamine oxidase B as a key target involved in serotonergic synapse dysfunction related to Alzheimer's disease. Molecular docking revealed that ferulic acid, a major bioactive compound in lingonberry, exhibits strong binding affinity to monoamine oxidase B. Further molecular dynamics simulations confirmed the stability of this interaction, highlighting the potential inhibitory effect of ferulic acid on monoamine oxidase B. These findings provide novel insights into the neuroprotective mechanisms of lingonberry and suggest its potential as a natural therapeutic intervention for Alzheimer's disease.

Mitochondrial protective properties exerted by JM-20 in a dementia model induced by intracerebroventricular administration of streptozotocin in mice

BACKGROUND

Mitochondrial dysfunction and brain insulin resistance have been related to Alzheimer's disease (AD) development. Streptozotocin (STZ) is commonly employed to disrupt glucose and insulin metabolism, even causing cognitive impairment in animal models. We aimed at studying the protective effect of JM-20 on STZ-induced memory impairment and brain mitochondrial dysfunction.

METHODS

Male C57Bl6 mice received 3 mg/kg STZ intracerebroventricularly and JM-20 (0.25 mg/kg or 4 mg/kg) was administered daily by gastric gavage. Episodic memory was evaluated through Y-maze, novel object recognition, and Morris water maze. Endogenous antioxidant systems (catalase and superoxide dismutase activities), total sulfhydryl groups, malondialdehyde levels were also studied and acetylcholinesterase (AChE) activity were assessed in the prefrontal cortex (PC) and hippocampus (HO).

RESULTS

demonstrated that STZ injection impaired recognition and spatial learning and memory and oxygen flow in all mitochondrial respiration states. Additionally, STZ increased AChE, superoxide dismutase, and catalase activity in the PC but not in HO tissue. A neuroprotective effect of JM-20 on STZ-induced memory decline, and mitochondrial dysfunction was observed, suggesting an important causal interaction. In addition, JM-20 was able to decreased AChE enzyme hyperactivity, rescued endogenous antioxidant systems, and prevented histologically observed neuronal damage CONCLUSION: Our results indicate that JM-20 protects against STZ-induced impairment in brain bioenergetic metabolism and memory, confirming its potential as a candidate for treating neurodegenerative disorders associated with mitochondrial dysfunction like AD.

Blood DNA methylation signature for incident dementia: Evidence from longitudinal cohorts

INTRODUCTION

Distinguishing between molecular changes that precede dementia onset and those resulting from the disease is challenging with cross-sectional studies.

METHODS

We studied blood DNA methylation (DNAm) differences and incident dementia in two large longitudinal cohorts: the Offspring cohort of the Framingham Heart Study (FHS) and the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. We analyzed blood DNAm samples from > 1000 cognitively unimpaired subjects.

RESULTS

Meta-analysis identified 44 CpGs and 44 differentially methylated regions consistently associated with time to dementia in both cohorts. Our integrative analysis identified early processes in dementia, such as immune responses and metabolic dysfunction. Furthermore, we developed a methylation-based risk score, which successfully predicted future cognitive decline in an independent validation set, even after accounting for age, sex, apolipoprotein E ε4, years of education, baseline diagnosis, and baseline Mini-Mental State Examination score.

DISCUSSION

DNAm offers a promising source as a biomarker for dementia risk assessment.

HIGHLIGHTS

Blood DNA methylation (DNAm) differences at individual CpGs and differentially methylated regions are significantly associated with incident dementia. Pathway analysis revealed DNAm differences associated with incident dementia are significantly enriched in biological pathways involved in immune responses and metabolic processes. Out-of-sample validation analysis demonstrated that a methylation-based risk score successfully predicted future cognitive decline in an independent dataset, even after accounting for age, sex, apolipoprotein E ε4, years of education, baseline diagnosis, and baseline Mini-Mental State Examination score.

The Potential Mechanism and the Role of Antioxidants in Mitigating Oxidative Stress in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent cause of dementia and a significant contributor to health issues and mortality among older individuals. This condition involves a progressive deterioration in cognitive function and the onset of dementia. Recent advancements suggest that the development of AD is more intricate than its underlying brain abnormalities alone. In addition, Alzheimer's disease, metabolic syndrome, and oxidative stress are all intricately linked to one another. Increased concentrations of circulating lipids and disturbances in glucose homeostasis contribute to the intensification of lipid oxidation, leading to a gradual depletion of the body's antioxidant defenses. This heightened oxidative metabolism adversely impacts cell integrity, resulting in neuronal damage. Pathways commonly acknowledged as contributors to AD pathogenesis include alterations in synaptic plasticity, disorganization of neurons, and cell death. Abnormal metabolism of some membrane proteins is thought to cause the creation of amyloid (Aβ) oligomers, which are extremely hazardous to neurotransmission pathways, especially those involving acetylcholine. The interaction between Aβ oligomers and these neurotransmitter systems is thought to induce cellular dysfunction, an imbalance in neurotransmitter signaling, and, ultimately, the manifestation of neurological symptoms. Antioxidants have a significant impact on human health since they may improve the aging process by combating free radicals. Neurodegenerative diseases are currently incurable; however, they may be effectively managed. An appealing alternative is the utilization of natural antioxidants, such as polyphenols, through diet or dietary supplements, which offer numerous advantages. Within this framework, we have extensively examined the importance of oxidative stress in the advancement of Alzheimer's disease, as well as the potential influence of antioxidants in mitigating its effects.

Understanding the menopause journey

The menopause experience is unique to people with ovaries who attain an age at which functioning follicles are depleted. Unlike male reproductive aging, menopause is accompanied by a definable reproductive milestone in that menstrual periods cease and the failure of follicle growth results in a large drop in circulating estrogen and no further ovarian production of progesterone. While the focus on menopause has largely been centered on this absence of hormone production, the most dynamic changes in symptoms and health markers begin before the final menstrual period, and merit attention. Vasomotor symptoms, the most common symptom of menopause and the primary symptom that drives women to seek treatment, peak in frequency and prevalence in the late menopause transition, when women are still having menstrual periods. Body composition and adverse lipoprotein and lipid changes also worsen most acutely in the late transition, and then assume a slower, age-related trajectory of change. Multiple processes that worsen across the transition restabilize after it is over. The notion that the menopause transition is an adaptive process for women has scientific merit and suggests that facilitating this adaptation and recognizing its implications may represent the next phase of progress in the field.

Metabolic Syndrome and the Risk of Alzheimer's Disease: A Meta-Analysis

Purpose: The relationship between metabolic syndrome (MetS) and the risk of Alzheimer's disease (AD) remains unclear. This meta-analysis aims to clarify the prospective association between MetS and AD risk and to explore how individual MetS components contribute to this relationship. Methods: Comprehensive searches of MEDLINE, Web of Science, and Embase were conducted up to April 12, 2024. Relevant prospective cohort studies were included. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to assess the associations. A random-effects model was used to incorporate the potential impact of heterogeneity. Findings: Six prospective cohort studies with seven datasets, including 484,994 participants and a follow-up of 3.5 to 13.0 years, were included. The pooled analysis showed no significant association between MetS and AD risk (HR: 0.96, 95% CI: 0.89-1.04, P = 0.37; I2 = 0%). Sensitivity and subgroup analyses confirmed these findings. Individual MetS components exhibited varied effects as follows: abdominal obesity was linked to a reduced AD risk (Risk ratio (RR): 0.70, 95% CI: 0.56-0.88, P = 0.002), whereas high blood pressure (BP) (RR: 1.15, 95% CI: 1.04-1.27, P = 0.007) and hyperglycemia (RR: 1.24, 95% CI: 1.08-1.42, P = 0.002) were associated with an increased risk. Low high-density lipoprotein cholesterol and high triglycerides showed no significant associations. Conclusions: This meta-analysis found no significant overall association between MetS and AD risk. However, specific MetS components, such as abdominal obesity, high BP, and hyperglycemia, may influence AD risk differently.

Elevated serum sodium is linked to increased amyloid-dependent tau pathology, neurodegeneration, and cognitive impairment in Alzheimer's disease

Vascular dysfunction is implicated in the pathophysiology of Alzheimer's disease (AD). While sodium is essential for maintaining vascular function, its role in AD pathology remains unclear. We included 353 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI), assessing serum sodium levels, cerebrospinal fluid (CSF) and positron emission tomography (PET) biomarkers, magnetic resonance imaging (MRI), and cognitive function. An independent sample (N = 471) with available CSF sodium-related proteins and AD biomarkers was also included. Associations between serum sodium levels and AD pathology, neurodegeneration, and cognition were evaluated using linear regression models. Spearman's correlation analyses assessed the relationships between CSF sodium-related proteins and AD biomarkers. Higher serum sodium levels were associated with increased AD pathology, reduced hippocampal volume, and greater cognitive decline (all p < 0.05). The relationship between serum sodium and amyloid PET was evident in several AD-susceptible brain regions, including the neocortex and limbic system. Individuals with high serum sodium exhibited higher tau pathology, lower hippocampal volume, and more severe cognitive decline per unit increase in amyloid PET compared to those with low serum sodium (all p < 0.05). Among the 14 CSF sodium-related proteins, which were inter-correlated, six were significantly correlated with CSF AD pathology and amyloid PET, while two were correlated with hippocampal volume and cognitive function, with sodium channel subunit beta-2 (SCN2B) and sodium channel subunit beta-3 (SCN3B) showing the strongest correlations. These findings underscore the crucial role of serum sodium in AD progression, highlighting a potential network of sodium dysregulation involved in AD pathology. Targeting sodium may offer a novel therapeutic approach to slowing AD progression, particularly by impeding the progression of amyloid-related downstream events.

Examining multimorbidity contributors to dementia over time

INTRODUCTION

Multimorbidity is associated with increased risk of dementia, but previous estimation of the joint contribution of constituent conditions to dementia incidence did not model additive contributions or temporal proximity in the sequential onset of conditions.

METHODS

Data were analyzed from 9944 Health and Retirement Study participants and Medicare fee-for-service beneficiaries, ages 68-99, without Alzheimer's disease and related dementias (ADRD) at baseline, from 1998-2016. ADRD and chronic condition were encoded using validated claims algorithms. We estimated the absolute contribution of eight conditions to ADRD with the longitudinal extension of the average attributable fraction (LE-AAF).

RESULTS

Hypertension, acute myocardial infarction, atrial fibrillation, diabetes, heart failure, ischemic heart disease, stroke, and arthritis additively accounted for 71.8% (95% confidence interval [CI]: 62.9%-79.1%) of ADRD incident cases based on LE-AAF.

DISCUSSION

Our findings suggest that multimorbidity plays a pivotal role in ADRD incidence. Targeting constituents of a cardiovascular path to dementia may contribute most to lowering dementia risk.

HIGHLIGHTS

Most dementia cases (71.8%) were attributable to eight chronic conditions. Hypertension was the largest contributor to dementia risk. Confidence intervals were smallest for constituents of a cardiovascular path to dementia. Longitudinal extension of the average attributable fractions (LE-AAFs) explicitly consider longitudinal patterns of comorbidities. Acute myocardial infarction did not contribute significantly to dementia incidence.

Influence of medical conditions on the diagnostic accuracy of plasma p-tau217 and p-tau217/Aβ42

INTRODUCTION

Blood-based biomarkers (BBMs) can enable early detection of brain amyloid beta (Aβ) pathology in cognitively unimpaired individuals. However, the extent to which common medical conditions affect biomarker performance remains unclear.

METHODS

Participants (n = 348) included individuals without cognitive impairment. We studied how brain Aβ associated with BBMs (Aβ42/40, phosphorylated tau [p-tau] 181 and 217, p-tau217/Aβ42, glial fibrillary acidic protein [GFAP], and neurofilament light [NfL]) and optimal BBM thresholds for predicting brain Aβ positivity and whether they are obscured by the presence of common medical conditions.

RESULTS

Plasma Aβ42/40, p-tau181, p-tau217, and GFAP, but not NfL, were significantly associated with brain Aβ. P-tau217/Aβ42 showed the best discriminative performance (area under the curve: 0.91). The strength of p-tau217-brain Aβ associations were obscured by diabetes and cardiovascular conditions.

DISCUSSION

These results suggest BBMs may help detect early Aβ pathology but suggest caution in their use due to common medical conditions that could affect accuracy.

HIGHLIGHTS

Plasma Aβ42/40, p-tau181, p-tau217, and GFAP but not NfL showed significant associations with brain Aβ. BBMs were more strongly associated with the level of brain Aβ in those without diabetes and cardiovascular conditions. P-tau217/Aβ42 showed the best performance (AUC = 0.91) in discriminating Aβ presence with an optimal cut-off of >1.2, followed by p-tau217 at >0.46 pg/mL, with performance slightly improving when excluding participants with cardiovascular conditions.

The potential link between the development of Alzheimer's disease and osteoporosis

Alzheimer's disease (AD) and osteoporosis (OP) pose distinct but interconnected health challenges, both significantly impacting the aging population. AD, a neurodegenerative disorder characterized by memory impairment and cognitive decline, is primarily associated with the accumulation of abnormally folded amyloid beta (Aβ) peptides and neurofibrillary tangles in the brain. OP, a skeletal disorder marked by low bone mineral density, involves dysregulation of bone remodeling and is associated with an increased risk of fractures. Recent studies have revealed an intriguing link between AD and OP, highlighting shared pathological features indicative of common regulatory pathophysiological pathways. In this article, we elucidate the signaling mechanisms that regulate the pathology of AD and OP and offer insights into the intricate network of factors contributing to these conditions. We also examine the role of bone-derived factors in the progression of AD, underscoring the plausibility of bidirectional communication between the brain and the skeletal system. The presence of amyloid plaques in the brain of individuals with AD is akin to the accumulation of brain Aβ in vascular dementia, pointing towards the need for further investigation of shared molecular mechanisms. Moreover, we discuss the role of bone-derived microRNAs that may regulate the pathological progression of AD, providing a novel perspective on the role of skeletal factors in neurodegenerative diseases. The insights presented here should help researchers engaged in exploring innovative therapeutic approaches targeting both neurodegenerative and skeletal disorders in aging populations.

Ketone body metabolism and the NLRP3 inflammasome in Alzheimer's disease

Alzheimer's disease (AD) is a degenerative brain disorder and the most common form of dementia. AD pathology is characterized by senile plaques and neurofibrillary tangles (NFTs) composed of amyloid-β (Aβ) and hyperphosphorylated tau, respectively. Neuroinflammation has been shown to drive Aβ and tau pathology, with evidence suggesting the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome as a key pathway in AD pathogenesis. NLRP3 inflammasome activation in microglia, the primary immune effector cells of the brain, results in caspase-1 activation and secretion of IL-1β and IL-18. Recent studies have demonstrated a dramatic interplay between the metabolic state and effector functions of immune cells. Microglial metabolism in AD is of particular interest, as ketone bodies (acetone, acetoacetate (AcAc), and β-hydroxybutyrate (BHB)) serve as an alternative energy source when glucose utilization is compromised in the brain of patients with AD. Furthermore, reduced cerebral glucose metabolism concomitant with increased BHB levels has been demonstrated to inhibit NLRP3 inflammasome activation. Here, we review the role of the NLRP3 inflammasome and microglial ketone body metabolism in AD pathogenesis. We also highlight NLRP3 inflammasome inhibition by several ketone body therapies as a promising new treatment strategy for AD.

Neuroprotective effects of GLP-1 receptor agonists in neurodegenerative Disorders: A Large-Scale Propensity-Matched cohort study

BACKGROUND

GLP-1 receptor agonists, traditionally used for treating type 2 diabetes mellitus and obesity, have demonstrated anti-inflammatory properties. However, their potential neuroprotective effects in neurodegenerative disorders remain unclear.

OBJECTIVE

To evaluate the impact of GLP-1 receptor agonists on the risk of developing various neurodegenerative conditions in obese patients.

METHODS

This comprehensive retrospective cohort study analyzed data from 5,307,845 obese adult patients across 73 healthcare organizations in 17 countries. Propensity score matching was performed, resulting in 102,935 patients in each cohort. We compared the risk of developing neurodegenerative disorders between obese patients receiving GLP-1 receptor agonist therapy and those who were not.

RESULTS

Obese patients treated with GLP-1 receptor agonists showed significantly lower risks of developing Alzheimer's disease (RR = 0.627, 95 %CI = 0.481-0.817), Lewy body dementia (RR = 0.590, 95 %CI = 0.462-0.753), and vascular dementia (RR = 0.438, 95 %CI = 0.327-0.588). The risk reduction for Parkinson's disease was not statistically significant overall (RR = 0.784, 95 %CI = 0.580-1.058) but was significant for semaglutide users (RR = 0.574, 95 %CI = 0.369-0.893). Semaglutide consistently showed the most pronounced protective effects across all disorders. Additionally, a significant reduction in all-cause mortality was observed (HR = 0.525, 95 %CI = 0.493-0.558).

CONCLUSION

This study provides evidence that the effects of GLP-1 receptor agonists may extend beyond their known metabolic and cardioprotective benefits to include neuroprotection, associated with a decreased risk of developing various neurodegenerative disorders. These findings suggest the potential for expanding the therapeutic applications of GLP-1 receptor agonists to improve neurocognitive outcomes. Further research is warranted to elucidate the mechanisms underlying these neuroprotective effects and to explore their clinical applications in neurodegenerative disease prevention and treatment.

Circadian Influences on Brain Lipid Metabolism and Neurodegenerative Diseases

Circadian rhythms are intrinsic, 24 h cycles that regulate key physiological, mental, and behavioral processes, including sleep-wake cycles, hormone secretion, and metabolism. These rhythms are controlled by the brain's suprachiasmatic nucleus, which synchronizes with environmental signals, such as light and temperature, and consequently maintains alignment with the day-night cycle. Molecular feedback loops, driven by core circadian "clock genes", such as Clock, Bmal1, Per, and Cry, are essential for rhythmic gene expression; disruptions in these feedback loops are associated with various health issues. Dysregulated lipid metabolism in the brain has been implicated in the pathogenesis of neurological disorders by contributing to oxidative stress, neuroinflammation, and synaptic dysfunction, as observed in conditions such as Alzheimer's and Parkinson's diseases. Disruptions in circadian gene expression have been shown to perturb lipid regulatory mechanisms in the brain, thereby triggering neuroinflammatory responses and oxidative damage. This review synthesizes current insights into the interconnections between circadian rhythms and lipid metabolism, with a focus on their roles in neurological health and disease. It further examines how the desynchronization of circadian genes affects lipid metabolism and explores the potential mechanisms through which disrupted circadian signaling might contribute to the pathophysiology of neurodegenerative disorders.

Assessing the Influence of Low Doses of Sucrose on Memory Deficits in Fish Exposed to Common Insecticide Based on Fipronil and Pyriproxyfen

Although pesticides have been a constant concern for decades, in the last ten years, public discussions and scientific research have emphasized their impact on human health and the environment, drawing increased attention to the problems associated with their use. The association of environmental stressors such as pesticides with a sugar-rich diet can contribute to the growing global metabolic disease epidemic through overlapping mechanisms of insulin resistance, inflammation, and metabolic dysregulation. The main aim of this study was to evaluate the behavioral effects of the exposure of Silver crucian carp (Carassius auratus gibelio) to a commercial insecticide formulation containing fipronil, pyriproxyfen, and other additives, as well as sucrose and their mixtures. The behavioral responses in the T-test showed significant abnormalities in the exploratory activity evocative of memory deficits and an increased degree of anxiety in the groups of fish treated with the insecticide formulation and the mixture of the insecticide with sucrose. Aggression, quantified in the mirror-biting test, as biting and the frequency of approaches to the mirror contact zone, was significantly decreased only in the insecticide and sucrose group. All three groups showed behavioral changes reflective of toxicity, but only the combination of the two stress factors, environmental (insecticide) and metabolic (sucrose intake), resulted in pronounced memory alterations.

Mitigation of Atherosclerotic Vascular Damage and Cognitive Improvement Through Mesenchymal Stem Cells in an Alzheimer's Disease Mouse Model

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive memory loss and other cognitive disturbances. Patients with AD can be vulnerable to vascular damage, and damaged vessels can lead to cognitive impairment. Mesenchymal stem cell (MSC) treatment has shown potential in ameliorating AD pathogenesis, but its effect on vascular function remains unclear. This study aimed to improve cognitive function by alleviating atherosclerosis-induced vessel damage using MSCs in mice with a genetic AD background. In this study, a 5xFAD mouse model of AD was used, and atherosclerotic vessel damage was induced by high-fat diets (HFDs). MSCs were injected into the tail vein along with mannitol in 5xFAD mice on an HFD. MSCs were detected in the brain, and vascular damage was improved following MSC treatment. Behavioral tests showed that MSCs enhanced cognitive function, as measured by the Y-maze and passive avoidance tests. Additionally, muscle strength measured by the rotarod test was also increased by MSCs in AD mice with vessel damage induced by HFDs. Overall, our results suggest that stem cells can alleviate vascular damage caused by metabolic diseases, including HFDs, and vascular disease in individuals carrying the AD gene. Consequently, this alleviates cognitive decline related to vascular dementia symptoms.

The Aggravating Role of Failing Neuropeptide Networks in the Development of Sporadic Alzheimer's Disease

Alzheimer's disease imposes an increasing burden on aging Western societies. The disorder most frequently appears in its sporadic form, which can be caused by environmental and polygenic factors or monogenic conditions of incomplete penetrance. According to the authors, in the majority of cases, Alzheimer's disease represents an aggravated form of the natural aging of the central nervous system. It can be characterized by the decreased elimination of amyloid β1-42 and the concomitant accumulation of degradation-resistant amyloid plaques. In the present paper, the dysfunction of neuropeptide regulators, which contributes to the pathophysiologic acceleration of senile dementia, is reviewed. However, in the present review, exclusively those neuropeptides or neuropeptide families are scrutinized, and the authors' investigations into their physiologic and pathophysiologic activities have made significant contributions to the literature. Therefore, the pathophysiologic role of orexins, neuromedins, RFamides, corticotrope-releasing hormone family, growth hormone-releasing hormone, gonadotropin-releasing hormone, ghrelin, apelin, and natriuretic peptides are discussed in detail. Finally, the therapeutic potential of neuropeptide antagonists and agonists in the inhibition of disease progression is discussed here.

Blood DNA Methylation Signature for Incident Dementia: Evidence from Longitudinal Cohorts

INTRODUCTION

Distinguishing between molecular changes that precede dementia onset and those resulting from the disease is challenging with cross-sectional studies.

METHODS

We studied blood DNA methylation (DNAm) differences and incident dementia in two large longitudinal cohorts: the Offspring cohort of the Framingham Heart Study (FHS) and the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. We analyzed blood DNAm samples from over 1,000 cognitively unimpaired subjects.

RESULTS

Meta-analysis identified 44 CpGs and 44 differentially methylated regions consistently associated with time to dementia in both cohorts. Our integrative analysis identified early processes in dementia, such as immune responses and metabolic dysfunction. Furthermore, we developed a Methylation-based Risk Score, which successfully predicted future cognitive decline in an independent validation set, even after accounting for age, sex, APOE ε4, years of education, baseline diagnosis, and baseline MMSE score.

DISCUSSION

DNA methylation offers a promising source of biomarker for early detection of dementia.

From Fundamentals to Innovation in Alzheimer's Disease: Molecular Findings and Revolutionary Therapies

Alzheimer's disease (AD) is a global health concern and the leading cause of dementia in the elderly. The prevalence of this neurodegenerative condition is projected to increase concomitantly with increased life expectancy, resulting in a significant economic burden. With very few FDA-approved disease-modifying drugs available for AD, there is an urgent need to develop new compounds capable of impeding the progression of the disease. Given the unclear etiopathogenesis of AD, this review emphasizes the underlying mechanisms of this condition. It explores not only well-studied aspects, such as the accumulation of Aβ plaques and neurofibrillary tangles, but also novel areas, including glymphatic and lymphatic pathways, microbiota and the gut-brain axis, serotoninergic and autophagy alterations, vascular dysfunction, the metal hypothesis, the olfactory pathway, and oral health. Furthermore, the potential molecular targets arising from all these mechanisms have been reviewed, along with novel promising approaches such as nanoparticle-based therapy, neural stem cell transplantation, vaccines, and CRISPR-Cas9-mediated genome editing techniques. Taking into account the overlap of these various mechanisms, individual and combination therapies emerge as the future direction in the AD strategy.

Mitochondrial Quality Control in Alzheimer's Disease: Insights from Caenorhabditis elegans Models

Alzheimer's disease (AD) is a complex neurodegenerative disorder that is classically defined by the extracellular deposition of senile plaques rich in amyloid-beta (Aβ) protein and the intracellular accumulation of neurofibrillary tangles (NFTs) that are rich in aberrantly modified tau protein. In addition to aggregative and proteostatic abnormalities, neurons affected by AD also frequently possess dysfunctional mitochondria and disrupted mitochondrial maintenance, such as the inability to eliminate damaged mitochondria via mitophagy. Decades have been spent interrogating the etiopathogenesis of AD, and contributions from model organism research have aided in developing a more fundamental understanding of molecular dysfunction caused by Aβ and toxic tau aggregates. The soil nematode C. elegans is a genetic model organism that has been widely used for interrogating neurodegenerative mechanisms including AD. In this review, we discuss the advantages and limitations of the many C. elegans AD models, with a special focus and discussion on how mitochondrial quality control pathways (namely mitophagy) may contribute to AD development. We also summarize evidence on how targeting mitophagy has been therapeutically beneficial in AD. Lastly, we delineate possible mechanisms that can work alone or in concert to ultimately lead to mitophagy impairment in neurons and may contribute to AD etiopathology.

Single Nuclei Transcriptomics Reveals Obesity-Induced Endothelial and Neurovascular Dysfunction: Implications for Cognitive Decline

Obesity confers risk for cardiovascular disease and vascular dementia. However, genomic alterations modulated by obesity in endothelial cells in the brain and their relationship to other neurovascular unit (NVU) cells are unknown. We performed single nuclei RNA sequencing (snRNAseq) of the NVU (endothelial cells, astrocytes, microglia, and neurons) from the hippocampus of obese (ob/ob) and wild-type (WT) male mice to characterize obesity-induced transcriptomic changes in a key brain memory center and assessed blood-brain barrier permeability (BBB) by gadolinium-enhanced magnetic resonance imaging (MRI). Ob/ob mice displayed obesity, hyperinsulinemia, and impaired glucose tolerance. snRNAseq profiled 14 distinct cell types and 32 clusters within the hippocampus of ob/ob and WT mice and uncovered differentially expressed genes (DEGs) in all NVU cell types, namely, 4462 in neurons, 1386 in astrocytes, 125 in endothelial cells, and 154 in microglia. Gene ontology analysis identified important biological processes such as angiogenesis in endothelial cells and synaptic trafficking in neurons. Cellular pathway analysis included focal adhesion and insulin signaling, which were common to all NVU cell types. Correlation analysis revealed significant positive correlations between endothelial cells and other NVU cell types. Differentially expressed long non-coding RNAs (lncRNAs) were observed in cells of the NVU-affecting pathways such as TNF and mTOR. BBB permeability showed a trend toward increased signal intensity in ob/ob mice. Taken together, our study provides in-depth insight into the molecular mechanisms underlying cognitive dysfunction in obesity and may have implications for therapeutic gene targeting.

A computational and machine learning approach to identify GPR40-targeting agonists for neurodegenerative disease treatment

The G protein-coupled receptor 40 (GPR40) is known to exert a significant influence on neurogenesis and neurodevelopment within the central nervous system of both humans and rodents. Research findings indicate that the activation of GPR40 by an agonist has been observed to promote the proliferation and viability of hypothalamus cells in the human body. The objective of the present study is to discover new agonist compounds for the GPR40 protein through the utilization of machine learning and pharmacophore-based screening techniques, in conjunction with other computational methodologies such as docking, molecular dynamics simulations, free energy calculations, and investigations of the free energy landscape. In the course of our investigation, we successfully identified five unreported agonist compounds that exhibit robust docking score, displayed stability in ligand RMSD and consistent hydrogen bonding with the receptor in the MD trajectories. Free energy calculations were observed to be higher than control molecule. The measured binding affinities of compounds namely 1, 3, 4, 6 and 10 were -13.9, -13.5, -13.4, -12.9, and -12.1 Kcal/mol, respectively. The identified molecular agonist that has been found can be assessed in terms of its therapeutic efficacy in the treatment of neurological diseases.

The association between urinary sodium and the risk of dementia: Evidence from a population-based cohort study

BACKGROUND

Sodium intake reduction is crucial for cardiovascular health, however, its lasting impact on dementia remains unclear.

METHODS

We included 458,577 UK Biobank participants without dementia at baseline. We estimated 24-h urinary sodium (E24hUNa) using spot urinary parameters and obtained the incidence of all-cause dementia, Alzheimer's disease, and vascular dementia from multiple sources.

RESULTS

The mean E24hUNa was 3.0 g (1st-99th percentile: 1.5 g-5.1 g). Over a mean follow-up of 13.6 years, 7886 (1.7 %) participants developed all-cause dementia, including 3763 (0.8 %) Alzheimer's disease and 1851 (0.4 %) vascular dementia. In the restricted cubic spline model, we identify a potential cutoff of 3.13 g for E24hUNa, below which each 1 g decrease in E24hUNa was associated with 21 % (95 % confidence interval [CI] 1.11-1.34) higher all-cause dementia risk and 35 % (95 % CI 1.11-1.63) higher vascular dementia risk (P-value <0.001 for non-linearity). The hazard ratios were 1.15 (95 % CI, 1.07-1.24) for all-cause dementia and 1.21 (95 % CI 1.04-1.40) for vascular dementia among individuals with E24hUNa below 3.13 g compared to those with E24hUNa higher than 3.13 g.

LIMITATIONS

One of the major limitations is the estimation of 24-h urinary sodium with spot urine samples.

CONCLUSIONS

An E24hUNa level below 3.13 g, equivalent to 3.37 g daily sodium intake, is associated with increased risks of all-cause and vascular dementia. This exploratory study suggests a potential lower limit below which the risk of dementia increases with a lower sodium level. Future studies are necessary to validate our findings.

Intranasal insulin effect on cognitive and/or memory impairment: a systematic review and meta-analysis

Background: Cognitive impairment, characterized by deficits in cognitive functions and loss of delayed and immediate recall, disproportionately affects individuals aged 65 years and older, particularly those with comorbid cardiovascular conditions such as hypertension and diabetes mellitus. Objective: This study aimed to investigate the potential association between intranasal insulin and cognitive and/or memory impairment, with a specific focus on delayed and immediate recall, considering the rising prevalence of cognitive disorders in the aging population. Methodology: Employing a rigorous systematic approach, we conducted a thorough search of MEDLINE, Scopus, the Cochrane database, and Web of Science from inception to November 23, 2022, identifying relevant randomized clinical trials. Our analyses encompassed three key aspects: (i) assessing the impact of intranasal insulin on cognitive impairment, (ii) evaluating its effect on delayed recall, and (iii) examining its influence on immediate recall. Results: Five studies meeting the inclusion criteria were included. The results underscored a statistically significant effect of intranasal insulin on delayed memory (effect size: 1.37; 95% CI: 0.65 to 2.09) and overall cognition (effect size: 0.58; 95% CI: 0.08 to 1.08). However, no statistically significant effect was observed for immediate memory (effect size: 0.48; 95% CI: -0.00 to 0.96). Conclusions: This study provides compelling evidence supporting the significance and efficacy of intranasal insulin in enhancing delayed recall and overall cognition. The observed effects hold promise for potential therapeutic interventions in addressing cognitive deficits associated with aging and comorbid conditions. The findings emphasize the need for further research to elucidate the underlying mechanisms and optimize the application of intranasal insulin in cognitive enhancement strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-024-10138-5.

A Compensatory Role of Physical Activity in the Association Between Sleep and Cognition

We synthesize evidence investigating the hypothesis that greater engagement in physical activity (PA) may compensate for some of the negative cognitive consequences associated with poor sleep in older adults. Potential mechanistic pathways include glymphatic clearance, influences on depression, and other comorbidities. The evidence base is largely cross-sectional and observational, and further experimental studies are required.

[Cognitive impairment in patients with obesity and impaired carbohydrate metabolism (dysglycemia)]

Obesity is a chronic disease, heterogeneous in etiology and clinical manifestations, progressing with a natural course, characterized by excessive deposition of fat mass in the body. This pathological condition has taken on the scale of a global epidemic in recent years, which continues to progress steadily, currently affecting more than 2 billion people worldwide. Due to its heterogeneity, obesity has a negative impact on the work of almost all organs and systems of the body, contributing to the emergence of new concomitant diseases and pathological conditions that significantly worsen the quality of life of these patients. Thus, a close relationship between type 2 diabetes mellitus and cognitive impairment has long been known, as well as with a number of other somatic diseases: coronary heart disease, atherosclerosis, non-alcoholic fatty liver disease, dyslipidemia, malignant neoplasms and other associated pathological conditions against the background of overweight and obesity.Currently, the problem of the relationship of cognitive impairment in patients with overweight or changes in the glycemic profile is very relevant, due to the high prevalence and insufficient study of this issue.

From Brain to Muscle: The Role of Muscle Tissue in Neurodegenerative Disorders

Neurodegenerative diseases (NDs), like amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), primarily affect the central nervous system, leading to progressive neuronal loss and motor and cognitive dysfunction. However, recent studies have revealed that muscle tissue also plays a significant role in these diseases. ALS is characterized by severe muscle wasting as a result of motor neuron degeneration, as well as alterations in gene expression, protein aggregation, and oxidative stress. Muscle atrophy and mitochondrial dysfunction are also observed in AD, which may exacerbate cognitive decline due to systemic metabolic dysregulation. PD patients exhibit muscle fiber atrophy, altered muscle composition, and α-synuclein aggregation within muscle cells, contributing to motor symptoms and disease progression. Systemic inflammation and impaired protein degradation pathways are common among these disorders, highlighting muscle tissue as a key player in disease progression. Understanding these muscle-related changes offers potential therapeutic avenues, such as targeting mitochondrial function, reducing inflammation, and promoting muscle regeneration with exercise and pharmacological interventions. This review emphasizes the importance of considering an integrative approach to neurodegenerative disease research, considering both central and peripheral pathological mechanisms, in order to develop more effective treatments and improve patient outcomes.

Modifying Alzheimer's disease pathophysiology with photobiomodulation: model, evidence, and future with EEG-guided intervention

This manuscript outlines a model of Alzheimer's Disease (AD) pathophysiology in progressive layers, from its genesis to the development of biomarkers and then to symptom expression. Genetic predispositions are the major factor that leads to mitochondrial dysfunction and subsequent amyloid and tau protein accumulation, which have been identified as hallmarks of AD. Extending beyond these accumulations, we explore a broader spectrum of pathophysiological aspects, including the blood-brain barrier, blood flow, vascular health, gut-brain microbiodata, glymphatic flow, metabolic syndrome, energy deficit, oxidative stress, calcium overload, inflammation, neuronal and synaptic loss, brain matter atrophy, and reduced growth factors. Photobiomodulation (PBM), which delivers near-infrared light to selected brain regions using portable devices, is introduced as a therapeutic approach. PBM has the potential to address each of these pathophysiological aspects, with data provided by various studies. They provide mechanistic support for largely small published clinical studies that demonstrate improvements in memory and cognition. They inform of PBM's potential to treat AD pending validation by large randomized controlled studies. The presentation of brain network and waveform changes on electroencephalography (EEG) provide the opportunity to use these data as a guide for the application of various PBM parameters to improve outcomes. These parameters include wavelength, power density, treatment duration, LED positioning, and pulse frequency. Pulsing at specific frequencies has been found to influence the expression of waveforms and modifications of brain networks. The expression stems from the modulation of cellular and protein structures as revealed in recent studies. These findings provide an EEG-based guide for the use of artificial intelligence to personalize AD treatment through EEG data feedback.

Polysaccharides from Trametes versicolor as a Potential Prebiotic to Improve the Gut Microbiota in High-Fat Diet Mice

Polysaccharides derived from Trametes versicolor have been found to exhibit hypolipidemic activity in hyperlipidemic mice, but the mechanism by which they modulate intestinal flora is still unclear. Currently, this study aimed to investigate the regulatory effects of extracellular (EPTV) and intracellular polysaccharides from T. versicolor (IPTV) on the dysbiosis of intestinal flora in mice fed a high-fat diet (HFD). The results showed that the oral administration of T. versicolor polysaccharides significantly ameliorated lipid accumulation and steatosis in hepatocytes. The gut dysbiosis in the HFD mice was characterized by a decrease in abundance and diversity of bacteria and an increase in the Firmicutes/Bacteroidetes ratio. However, T. versicolor polysaccharides attenuated these changes and reduced the relative abundance of bile-salt-hydrolase (BSH)-producing bacteria, such as Bacillus, Enterococcus, Bifidobacterium, and Lactococcus. It is noteworthy that T. versicolor polysaccharides also restored the disorganization of intestinal fungi in HFD mice, with EPTV treatment leading to a higher relative abundance of Basidiomycota and Ascomycota compared to IPTV. Additionally, T. versicolor polysaccharides enhanced the growth of butyrate-producing bacteria via the buk and but pathways, accompanied by an increase in short-chain fatty acids (SCFAs), especially butyrate. IPTV also increased the expression of G-protein-coupled receptors 41 (GPR41) and 43 (GPR43) by 40.52% and 113.24% each, as compared to 62.42% and 110.28%, respectively, for EPTV. It is suggested that IPTV and EPTV have the potential to counteract hyperlipidemia-associated intestinal flora disorders and improve lipid metabolism.

Osteoporosis and Alzheimer´s disease (or Alzheimer´s disease and Osteoporosis)

Alzheimer's disease (AD) and osteoporosis are two diseases that mainly affect elderly people, with increases in the occurrence of cases due to a longer life expectancy. Several epidemiological studies have shown a reciprocal association between both diseases, finding an increase in incidence of osteoporosis in patients with AD, and a higher burden of AD in osteoporotic patients. This epidemiological relationship has motivated the search for molecules, genes, signaling pathways and mechanisms that are related to both pathologies. The mechanisms found in these studies can serve to improve treatments and establish better patient care protocols.

The potential role of gut microbiota-derived metabolites as regulators of metabolic syndrome-associated mitochondrial and endolysosomal dysfunction in Alzheimer's disease

Although the role of gut microbiota (GMB)-derived metabolites in mitochondrial and endolysosomal dysfunction in Alzheimer's disease (AD) under metabolic syndrome remains unclear, deciphering these host-metabolite interactions represents a major public health challenge. Dysfunction of mitochondria and endolysosomal networks (ELNs) plays a crucial role in metabolic syndrome and can exacerbate AD progression, highlighting the need to study their reciprocal regulation for a better understanding of how AD is linked to metabolic syndrome. Concurrently, metabolic disorders are associated with alterations in the composition of the GMB. Recent evidence suggests that changes in the composition of the GMB and its metabolites may be involved in AD pathology. This review highlights the mechanisms of metabolic syndrome-mediated AD development, focusing on the interconnected roles of mitochondrial dysfunction, ELN abnormalities, and changes in the GMB and its metabolites. We also discuss the pathophysiological role of GMB-derived metabolites, including amino acids, fatty acids, other metabolites, and extracellular vesicles, in mediating their effects on mitochondrial and ELN dysfunction. Finally, this review proposes therapeutic strategies for AD by directly modulating mitochondrial and ELN functions through targeting GMB metabolites under metabolic syndrome.

Association between Visceral Adipose Tissue Metabolism and Cerebral Glucose Metabolism in Patients with Cognitive Impairment

Visceral adipose tissue (VAT) dysfunction has been recently recognized as a potential contributor to the development of Alzheimer's disease (AD). This study aimed to explore the relationship between VAT metabolism and cerebral glucose metabolism in patients with cognitive impairment. This cross-sectional prospective study included 54 patients who underwent 18F-fluorodeoxyglucose (18F-FDG) brain and torso positron emission tomography/computed tomography (PET/CT), and neuropsychological evaluations. VAT metabolism was measured by 18F-FDG torso PET/CT, and cerebral glucose metabolism was measured using 18F-FDG brain PET/CT. A voxel-based analysis revealed that the high-VAT-metabolism group exhibited a significantly lower cerebral glucose metabolism in AD-signature regions such as the parietal and temporal cortices. In the volume-of-interest analysis, multiple linear regression analyses with adjustment for age, sex, and white matter hyperintensity volume revealed that VAT metabolism was negatively associated with cerebral glucose metabolism in AD-signature regions. In addition, higher VAT metabolism was correlated with poorer outcomes on cognitive assessments, including the Korean Boston Naming Test, Rey Complex Figure Test immediate recall, and the Controlled Oral Word Association Test. In conclusion, our study revealed significant relationships among VAT metabolism, cerebral glucose metabolism, and cognitive function. This suggests that VAT dysfunction actively contributes to the neurodegenerative processes characteristic of AD, making VAT dysfunction targeting a novel AD therapy approach.

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.

Brain microvascular endothelial cell metabolism and its ties to barrier function

Brain microvascular endothelial cells, which lie at the interface between blood and brain, are critical to brain energetics. These cells must precisely balance metabolizing nutrients for their own demands with transporting nutrients into the brain to sustain parenchymal cells. It is essential to understand this integrated metabolism and transport so that we can develop better diagnostics and therapeutics for neurodegenerative diseases such as Alzheimer's disease, multiple sclerosis, and traumatic brain injury. In this chapter, we first describe brain microvascular endothelial cell metabolism and how these cells regulate both blood flow and nutrient transport. We then explain the impact of brain microvascular endothelial cell metabolism on the integrity of the blood-brain barrier, as well as how metabolites produced by the endothelial cells impact other brain cells. We detail some ways that cell metabolism is typically measured experimentally and modeled computationally. Finally, we describe changes in brain microvascular endothelial cell metabolism in aging and neurodegenerative diseases. At the end of the chapter, we highlight areas for future research in brain microvascular endothelial cell metabolism. The goal of this chapter is to underscore the importance of nutrient metabolism and transport at the brain endothelium for cerebral health and neurovascular disease treatment.

Plasma Leptin and Alzheimer Protein Pathologies Among Older Adults

Importance

Many epidemiologic studies have suggested that low levels of plasma leptin, a major adipokine, are associated with increased risk of Alzheimer disease (AD) dementia and cognitive decline. Nevertheless, the mechanistic pathway linking plasma leptin and AD-related cognitive decline is not yet fully understood.

Objective

To examine the association of plasma leptin levels with in vivo AD pathologies, including amyloid-beta (Aβ) and tau deposition, through both cross-sectional and longitudinal approaches among cognitively unimpaired older adults.

Design, Setting, and Participants

This was a longitudinal cohort study from the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer Disease. Data were collected from January 1, 2014, to December 31, 2020, and data were analyzed from July 11 to September 6, 2022. The study included a total of 208 cognitively unimpaired participants who underwent baseline positron emission tomography (PET) scans for brain Aβ deposition. For longitudinal analyses, 192 participants who completed both baseline and 2-year follow-up PET scans for brain Aβ deposition were included.

Exposure

Plasma leptin levels as assessed by enzyme-linked immunosorbent assay.

Main Outcomes and Measures

Baseline levels and longitudinal changes of global Aβ and AD-signature region tau deposition measured by PET scans.

Results

Among the 208 participants, the mean (SD) age was 66.0 (11.3) years, 114 were women (54.8%), and 37 were apolipoprotein E ε4 carriers (17.8%). Lower plasma leptin levels had a significant cross-sectional association with greater brain Aβ deposition (β = -0.04; 95% CI, -0.09 to 0.00; P = .046), while there was no significant association between plasma leptin levels and tau deposition (β = -0.02; 95% CI, -0.05 to 0.02; P = .41). In contrast, longitudinal analyses revealed that there was a significant association between lower baseline leptin levels and greater increase of tau deposition over 2 years (β = -0.06; 95% CI, -0.11 to -0.01; P = .03), whereas plasma leptin levels did not have a significant association with longitudinal change of Aβ deposition (β = 0.006; 95% CI, 0.00-0.02; P = .27).

Conclusions and Relevance

The present findings suggest that plasma leptin may be protective for the development or progression of AD pathology, including both Aβ and tau deposition.

Erjingwan and Alzheimer's disease: research based on network pharmacology and experimental confirmation

Background

Alzheimer's disease (AD), a challenging neurodegenerative condition, has emerged as a significant global public health concern. The Chinese medicine decoction Erjingwan (EJW) has shown promising efficacy in AD treatment, though its mechanism remains unclear.

Objective

This study aims to elucidate the mechanism by which EJW treats AD through network pharmacology analysis and in vivo experiments.

Methods

We identified EJW's components using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database and determined AD-related targets from various databases. A network comprising herbs-compounds-targets was established, and EJW's core targets were ascertained through protein-protein interaction (PPI) analysis. This study assessed the cognitive abilities of APP/PS1 mice using Morris water mazes and Y mazes, in addition to analyzing blood samples for triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels. Brain tissues were examined histologically with HE staining, Nissl staining, and immunohistochemistry (IHC) for amyloid β-protein (Aβ) detection. Superoxide dismutase (SOD), reactive oxygen species (ROS), Interleukin-1β (IL-1β), and Interleukin-6 (IL-6) levels in the hippocampal region were measured by ELISA. mRNA expression of apolipoprotein A-I (APOA-I), apolipoprotein B (APOB), apolipoprotein E4 (APOE4), advanced glycation end products (AGE), the receptor for AGE (RAGE), and nuclear factor kappa-B (NF-κB) was evaluated by quantitative PCR (q-PCR). Western blotting was used to detect the expression of AGE, RAGE, NF-κB, and Tau protein.

Results

Screening identified 57 chemical components and 222 potential targets of EJW. Ten core targets for AD treatment were identified, with enrichment analysis suggesting EJW's effects are related to lipid metabolism and AGEs/RAGE pathways. EJW enhanced learning and memory in APP/PS1 mice, protected neuronal structure in the hippocampal region, reduced Aβ deposition, and altered levels of TG, TC, LDL, IL-1β, and IL-6, and the expression of APOE4, AGEs, RAGE, NF-κB, and Tau protein, while increasing SOD, APOA-I, and APOB mRNA expression.

Conclusion

The study identified four core components of EJW-iosgenin, baicalein, beta-sitosterol, quercetin-and ten core targets including AKT1, IL6, VEGFA, TP53, CASP3, for treating AD. Experimental results demonstrate EJW's capacity to modulate lipid profiles, reduce pathological markers such as Aβ1-42, Tau, IL-6, IL-1β, reactive oxygen species, SOD, and enhance cognitive functions in APP/PS1 mice, potentially through inhibiting the AGEs/RAGE/NF-κB pathway.

Towards a Deeper Understanding: Utilizing Machine Learning to Investigate the Association between Obesity and Cognitive Decline-A Systematic Review

Background/Objectives: Several studies have shown a relation between obesity and cognitive decline, highlighting a significant global health challenge. In recent years, artificial intelligence (AI) and machine learning (ML) have been integrated into clinical practice for analyzing datasets to identify new risk factors, build predictive models, and develop personalized interventions, thereby providing useful information to healthcare professionals. This systematic review aims to evaluate the potential of AI and ML techniques in addressing the relationship between obesity, its associated health consequences, and cognitive decline. Methods: Systematic searches were performed in PubMed, Cochrane, Web of Science, Scopus, Embase, and PsycInfo databases, which yielded eight studies. After reading the full text of the selected studies and applying predefined inclusion criteria, eight studies were included based on pertinence and relevance to the topic. Results: The findings underscore the utility of AI and ML in assessing risk and predicting cognitive decline in obese patients. Furthermore, these new technology models identified key risk factors and predictive biomarkers, paving the way for tailored prevention strategies and treatment plans. Conclusions: The early detection, prevention, and personalized interventions facilitated by these technologies can significantly reduce costs and time. Future research should assess ethical considerations, data privacy, and equitable access for all.

The advent of RNA-based therapeutics for metabolic syndrome and associated conditions: a comprehensive review of the literature

Metabolic syndrome (MetS) is a prevalent and intricate health condition affecting a significant global population, characterized by a cluster of metabolic and hormonal disorders disrupting lipid and glucose metabolism pathways. Clinical manifestations encompass obesity, dyslipidemia, insulin resistance, and hypertension, contributing to heightened risks of diabetes and cardiovascular diseases. Existing medications often fall short in addressing the syndrome's multifaceted nature, leading to suboptimal treatment outcomes and potential long-term health risks. This scenario underscores the pressing need for innovative therapeutic approaches in MetS management. RNA-based treatments, employing small interfering RNAs (siRNAs), microRNAs (miRNAs), and antisense oligonucleotides (ASOs), emerge as promising strategies to target underlying biological abnormalities. However, a summary of research available on the role of RNA-based therapeutics in MetS and related co-morbidities is limited. Murine models and human studies have been separately interrogated to determine whether there have been recent advancements in RNA-based therapeutics to offer a comprehensive understanding of treatment available for MetS. In a narrative fashion, we searched for relevant articles pertaining to MetS co-morbidities such as cardiovascular disease, fatty liver disease, dementia, colorectal cancer, and endocrine abnormalities. We emphasize the urgency of exploring novel therapeutic avenues to address the intricate pathophysiology of MetS and underscore the potential of RNA-based treatments, coupled with advanced delivery systems, as a transformative approach for achieving more comprehensive and efficacious outcomes in MetS patients.

Protection against APOE4 -associated aging phenotypes with the longevity-promoting intervention 17α-estradiol in male mice

The apolipoprotein ε4 allele ( APOE4 ) is associated with decreased longevity, increased vulnerability to age-related declines, and disorders across multiple systems. Interventions that promote healthspan and lifespan represent a promising strategy to attenuate the development of APOE4 -associated aging phenotypes. Here we studied the ability of the longevity-promoting intervention 17α-estradiol (17αE2) to protect against age-related impairments in APOE4 versus the predominant APOE3 genotype using early middle-aged mice with knock-in of human APOE alleles. Beginning at age 10 months, male APOE3 or APOE4 mice were treated for 20 weeks with 17αE2 or vehicle then compared for indices of aging phenotypes body-wide. Across peripheral and neural measures, APOE4 was associated with poorer outcomes. Notably, 17αE2 treatment improved outcomes in a genotype-dependent manner favoring APOE4 mice. These data demonstrate a positive APOE4 bias in 17αE2-mediated healthspan actions, suggesting that longevity-promoting interventions may be useful in mitigating deleterious age-related risks associated with APOE4 genotype.

The association of GNB5 with Alzheimer disease revealed by genomic analysis restricted to variants impacting gene function

Disease-associated variants identified from genome-wide association studies (GWASs) frequently map to non-coding areas of the genome such as introns and intergenic regions. An exclusive reliance on gene-agnostic methods of genomic investigation could limit the identification of relevant genes associated with polygenic diseases such as Alzheimer disease (AD). To overcome such potential restriction, we developed a gene-constrained analytical method that considers only moderate- and high-risk variants that affect gene coding sequences. We report here the application of this approach to publicly available datasets containing 181,388 individuals without and with AD and the resulting identification of 660 genes potentially linked to the higher AD prevalence among Africans/African Americans. By integration with transcriptome analysis of 23 brain regions from 2,728 AD case-control samples, we concentrated on nine genes that potentially enhance the risk of AD: AACS, GNB5, GNS, HIPK3, MED13, SHC2, SLC22A5, VPS35, and ZNF398. GNB5, the fifth member of the heterotrimeric G protein beta family encoding Gβ5, is primarily expressed in neurons and is essential for normal neuronal development in mouse brain. Homozygous or compound heterozygous loss of function of GNB5 in humans has previously been associated with a syndrome of developmental delay, cognitive impairment, and cardiac arrhythmia. In validation experiments, we confirmed that Gnb5 heterozygosity enhanced the formation of both amyloid plaques and neurofibrillary tangles in the brains of AD model mice. These results suggest that gene-constrained analysis can complement the power of GWASs in the identification of AD-associated genes and may be more broadly applicable to other polygenic diseases.

Astrocyte response to melatonin treatment in rats under high-carbohydrate high-fat diet

The involvement of consumption of high-carbohydrate high-fat (HCHF) diet in cognitive impairment is attributed, at least in part, to the activation of astrocytes, which contributes to the development of neuroinflammation, oxidative stress, and subsequent cognitive deficits. This study aimed to assess the influence of melatonin on cognitive impairment and astrogliosis induced by the HCHF diet in rats. Male Wistar rats were fed an HCHF diet for eight weeks to induce obesity and metabolic syndrome. Subsequently, they received oral melatonin treatment for four weeks at doses of 5 mg/kg, 10 mg/kg, and 30 mg/kg, alongside the HCHF diet. Cognitive function was evaluated using the Y-maze test, while the levels of proinflammatory cytokines, oxidative stress, and the number glial fibrillary acidic protein (GFAP) positive cells were assessed in the hippocampi and hypothalamus. The consumption of the HCHF diet resulted in weight gain, hyperlipidemia, impaired glucose tolerance, cognitive decline, neuroinflammation, oxidative stress damage, and astrogliosis in rats. Although melatonin treatment did not demonstrate beneficial effects on blood glucose and lipid metabolism, it improved the impaired working memory caused by the HCHF diet. Melatonin exhibited a dose-dependent reduction of astrogliosis, neuroinflammation, and lipid peroxidation while restored superoxide dismutase in the hippocampus and hypothalamus of HCHF diet-treated rats. These findings provide evidence that melatonin inhibits astrocyte activation, thereby attenuating inflammation and minimizing oxidative stress damage induced by the HCHF diet.

Intrinsic running capacity associates with hippocampal electrophysiology and long-term potentiation in rats

Good aerobic and metabolic fitness associates with better cognitive performance and brain health. Conversely, poor metabolic health predisposes to neurodegenerative diseases. Our previous findings indicate that rats selectively bred for Low Capacity for Running (LCR) show less synaptic plasticity and more inflammation in the hippocampus and perform worse in tasks requiring flexible cognition than rats bred for High Capacity for Running (HCR). Here we aimed to determine whether hippocampal electrophysiological activity related to learning and memory would be impaired in LCR compared to HCR rats. We also studied whether an exercise intervention could even out the possible differences. We conducted in vivo recordings from the dorsal hippocampus under terminal urethane anesthesia in middle-aged sedentary males and female rats, and in females allowed to access running wheels for 6 weeks. Our results indicate stronger long-term potentiation (LTP) in the CA3-CA1 synapse in HCR than LCR rats, and in female than male rats. Compared to LCR rats, HCR rats had more dentate spikes and more gamma epochs, the occurrence of which also correlated positively with the magnitude of LTP. Voluntary running reduced the differences between female LCR and HCR rats. In conclusion, low innate fitness links to reduced hippocampal function and plasticity which can seems to improve with voluntary aerobic exercise even in middle age.

How cy pres promotes transdisciplinary convergence science: an academic health center for women's cardiovascular and brain health

Cardiovascular disease (CVD) is largely preventable, and the leading cause of death for men and women. Though women have increased life expectancy compared to men, there are marked sex disparities in prevalence and risk of CVD-associated mortality and dementia. Yet, the basis for these and female-male differences is not completely understood. It is increasingly recognized that heart and brain health represent a lifetime of exposures to shared risk factors (including obesity, hyperlipidemia, diabetes, and hypertension) that compromise cerebrovascular health. We describe the process and resources for establishing a new research Center for Women's Cardiovascular and Brain Health at the University of California, Davis as a model for: (1) use of the cy pres principle for funding science to improve health; (2) transdisciplinary collaboration to leapfrog progress in a convergence science approach that acknowledges and addresses social determinants of health; and (3) training the next generation of diverse researchers. This may serve as a blueprint for future Centers in academic health institutions, as the cy pres mechanism for funding research is a unique mechanism to leverage residual legal settlement funds to catalyze the pace of scientific discovery, maximize innovation, and promote health equity in addressing society's most vexing health problems.

Metabolic Syndrome Status Changes and Cognitive Functioning: Insights from the Lifelines Cohort Study

BACKGROUND

Metabolic syndrome is associated with increased risk of dementia. Yet, findings on how longitudinal development of metabolic syndrome status affects cognition remain controversial.

OBJECTIVES

This study examines whether individuals with different changes in metabolic syndrome status differ in cognitive functioning. Additionally, the prevalence of metabolic syndrome within the Lifelines population-based study is investigated.

DESIGN

14609 Lifelines participants (mean age 60.8, 56.4% women) were divided into four groups based on their metabolic syndrome status changes between 2007-2013 (1) and between 2014-2017 (2): without metabolic syndrome (N=10863; absent at 1 and 2), de novo metabolic syndrome (N=1340; absent at 1 and present at 2), remitting metabolic syndrome (N=825; present at 1 and absent at 2), and persistent metabolic syndrome (N=1581; present at 1 and 2). ANCOVA models were employed to assess group differences in psychomotor function, visual attention, visual learning, and working memory assessed using the Cogstate Brief Battery.

RESULTS

Accounting for education, age, sex, and time between examinations, groups did not statistically differ in any of the four cognitive outcomes. The prevalence of metabolic syndrome within the Lifelines population increased with age and differed among men and women.

CONCLUSION

Performance in psychomotor function, visual attention, visual learning, and working memory measured by the Cogstate Brief Battery did not differ between individuals with different changes in metabolic syndrome. The length of metabolic syndrome exposure was unknown, making our results exploratory and calling for future studies addressing this gap.

Navigating the Alzheimer's Treatment Landscape: Unraveling Amyloid-beta Complexities and Pioneering Precision Medicine Approaches

A variety of cutting-edge methods and good knowledge of the illness's complex causes are causing a sea change in the field of Alzheimer's Disease (A.D.) research and treatment. Precision medicine is at the vanguard of this change, where individualized treatment plans based on genetic and biomarker profiles give a ray of hope for customized therapeutics. Combination therapies are becoming increasingly popular as a way to address the multifaceted pathology of Alzheimer's by simultaneously attacking Aβ plaques, tau tangles, neuroinflammation, and other factors. The article covers several therapeutic design efforts, including BACE inhibitors, gamma- secretase modulators, monoclonal antibodies (e.g., Aducanumab and Lecanemab), and anti- Aβ vaccinations. While these techniques appear promising, clinical development faces safety concerns and uneven efficacy. To address the complicated Aβ pathology in Alzheimer's disease, a multimodal approach is necessary. The statement emphasizes the continued importance of clinical trials in addressing safety and efficacy concerns. Looking ahead, it suggests that future treatments may take into account genetic and biomarker traits in order to provide more personalized care. Therapies targeting Aβ, tau tangles, neuroinflammation, and novel drug delivery modalities are planned. Nanoparticles and gene therapies are only two examples of novel drug delivery methods that have the potential to deliver treatments more effectively, with fewer side effects, and with better therapeutic results. In addition, medicines that target tau proteins in addition to Aβ are in the works. Early intervention, based on precise biomarkers, is a linchpin of Alzheimer's care, emphasizing the critical need for detecting the disease at its earliest stages. Lifestyle interventions, encompassing diet, exercise, cognitive training, and social engagement, are emerging as key components in the fight against cognitive decline. Data analytics and art are gaining prominence as strategies to mitigate the brain's inflammatory responses. To pool knowledge and resources in the fight against Alzheimer's, international cooperation between scientists, doctors, and pharmaceutical companies is still essential. In essence, a complex, individualized, and collaborative strategy will characterize Alzheimer's research and therapy in the future. Despite obstacles, these encouraging possibilities show the ongoing commitment of the scientific and medical communities to combat A.D. head-on, providing a glimmer of hope to the countless people and families touched by this savage sickness.

Recent Advances in Drug Delivery Systems Targeting Insulin Signalling for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by the accumulation of neurofibrillary tangles and amyloid-β plaques. Recent research has unveiled the pivotal role of insulin signaling dysfunction in the pathogenesis of AD. Insulin, once thought to be unrelated to brain function, has emerged as a crucial factor in neuronal survival, synaptic plasticity, and cognitive processes. Insulin and the downstream insulin signaling molecules are found mainly in the hippocampus and cortex. Some molecules responsible for dysfunction in insulin signaling are GSK-3β, Akt, PI3K, and IRS. Irregularities in insulin signaling or insulin resistance may arise from changes in the phosphorylation levels of key molecules, which can be influenced by both stimulation and inactivity. This, in turn, is believed to be a crucial factor contributing to the development of AD, which is characterized by oxidative stress, neuroinflammation, and other pathological hallmarks. Furthermore, this route is known to be indirectly influenced by Nrf2, NF-κB, and the caspases. This mini-review delves into the intricate relationship between insulin signaling and AD, exploring how disruptions in this pathway contribute to disease progression. Moreover, we examine recent advances in drug delivery systems designed to target insulin signaling for AD treatment. From oral insulin delivery to innovative nanoparticle approaches and intranasal administration, these strategies hold promise in mitigating the impact of insulin resistance on AD. This review consolidates current knowledge to shed light on the potential of these interventions as targeted therapeutic options for AD.

Monoclonal Antibody Therapy in Alzheimer's Disease

Alzheimer's disease is a neurodegenerative condition marked by the progressive deterioration of cognitive abilities, memory impairment, and the accumulation of abnormal proteins, specifically beta-amyloid plaques and tau tangles, within the brain. Despite extensive research efforts, Alzheimer's disease remains without a cure, presenting a significant global healthcare challenge. Recently, there has been an increased focus on antibody-based treatments as a potentially effective method for dealing with Alzheimer's disease. This paper offers a comprehensive overview of the current status of research on antibody-based molecules as therapies for Alzheimer's disease. We will briefly mention their mechanisms of action, therapeutic efficacy, and safety profiles while addressing the challenges and limitations encountered during their development. We also highlight some crucial considerations in antibody-based treatment development, including patient selection criteria, dosing regimens, or safety concerns. In conclusion, antibody-based therapies present a hopeful outlook for addressing Alzheimer's disease. While challenges remain, the accumulating evidence suggests that these therapies may offer substantial promise in ameliorating or preventing the progression of this debilitating condition, thus potentially enhancing the quality of life for the millions of individuals and families affected by Alzheimer's disease worldwide.

Hypertension linked to Alzheimer's disease via stroke: Mendelian randomization

This study aimed to investigate the relationship between hypertension and Alzheimer's disease (AD) and demonstrate the key role of stroke in this relationship using mediating Mendelian randomization. AD, a neurodegenerative disease characterized by memory loss, cognitive impairment, and behavioral abnormalities, severely affects the quality of life of patients. Hypertension is an important risk factor for AD. However, the precise mechanism underlying this relationship is unclear. To investigate the relationship between hypertension and AD, we used a mediated Mendelian randomization method and screened for mediating variables between hypertension and AD by setting instrumental variables. The results of the mediated analysis showed that stroke, as a mediating variable, plays an important role in the causal relationship between hypertension and AD. Specifically, the mediated indirect effect value for stroke obtained using multivariate mediated MR analysis was 54.9%. This implies that approximately 55% of the risk of AD owing to hypertension can be attributed to stroke. The results suggest that the increased risk of AD owing to hypertension is mediated through stroke. The finding not only sheds light on the relationship between hypertension and AD but also indicates novel methods for the prevention and treatment of AD. By identifying the critical role of stroke in the link between hypertension and AD, this study provides insights into potential interventions that could mitigate the impact of hypertension on AD. This could help develop personalized treatments and help improve the quality of life of patients with AD who suffer from hypertension.