How Can Insulin Resistance Cause Alzheimer's Disease?

The double life of glucose metabolism: brain health, glycemic homeostasis, and your patients with type 2 diabetes

The maintenance of cognitive function is essential for quality of life and health outcomes in later years. Cognitive impairment, however, remains an undervalued long-term complication of type 2 diabetes by patients and providers alike. The burden of sustained hyperglycemia includes not only cognitive deficits but also the onset and progression of dementia-related conditions, including Alzheimer's disease (AD). Recent research has shown that the brain maintains an independent glucose "microsystem"-evolved to ensure the availability of fuel for brain neurons without interruption by transient hypoglycemia. When this milieu is perturbed, brain hyperglycemia, brain glucotoxicity, and brain insulin resistance can ensue and interfere with insulin signaling, a key pathway to cognitive function and neuronal integrity. This newly understood brain homeostatic system operates semi-autonomously from the systemic glucoregulatory apparatus. Large-scale clinical studies have shown that systemic dysglycemia is also strongly associated with poorer cognitive outcomes, which can be mitigated through appropriate clinical management of plasma glucose levels. Moreover, these studies demonstrated that glucose-lowering agents are not equally effective at preventing cognitive dysfunction. Glucagon-like peptide-1 (GLP-1) receptor analogs and sodium glucose cotransporter 2 inhibitors (SGLT2is) appear to afford the greatest protection; metformin and dipeptidyl peptidase 4 inhibitors (DPP-4is) also significantly improved cognitive outcomes. Sulfonylureas (SUs) and exogenous insulin, on the other hand, do not provide the same protection and may actually worsen cognitive outcomes. In the creation of a treatment plan, comorbid cognitive conditions should be considered. These efficacious treatments create a new gold standard of managing hyperglycemia-one which is consistent with the "complication-centric prescribing" mandates issued in type 2 diabetes treatment guidelines. The increasing longevity enjoyed by our populace places the onus on clinical care to play the "long game" in using targeted treatments for glucose control in patients with, or at risk for, cognitive decline to maintain cognitive wellness later in life. This article reviews critical emerging data for scientists and trialists and translates new enhancements in patient care for practitioners.

Recent Progress in Nanomedicine for the Diagnosis and Treatment of Alzheimer's Diseases

Alzheimer's disease (AD) is a neurodegenerative disease that causes memory loss and progressive and permanent deterioration of cognitive function. The most challenging issue in combating AD is its complicated pathogenesis, which includes the deposition of amyloid β (Aβ) plaques, intracellular hyperphosphorylated tau protein, neurofibrillary tangles (NFT), etc. Despite rapid advancements in mechanistic research and drug development for AD, the currently developed drugs only improve cognitive ability and temporarily relieve symptoms but cannot prevent the development of AD. Moreover, the blood-brain barrier (BBB) creates a huge barrier to drug delivery in the brain. Therefore, effective diagnostic tools and treatments are urgently needed. In recent years, nanomedicine has provided opportunities to overcome the challenges and limitations associated with traditional diagnostics or treatments. Various types of nanoparticles (NPs) play an essential role in nanomedicine for the diagnosis and treatment of AD, acting as drug carriers to improve targeting and bioavailability across/bypass the BBB or acting as drugs directly on AD lesions. This review categorizes different types of NPs and summarizes their applications in nanomedicine for the diagnosis and treatment of AD. It also discusses the challenges associated with clinical applications and explores the latest developments and prospects of nanomedicine for AD.

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.

Alzheimer's Disease as Type 3 Diabetes: Understanding the Link and Implications

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are two prevalent conditions that present considerable public health issue in aging populations worldwide. Recent research has proposed a novel conceptualization of AD as "type 3 diabetes", highlighting the critical roles of insulin resistance and impaired glucose metabolism in the pathogenesis of the disease. This article examines the implications of this association, exploring potential new avenues for treatment and preventive strategies for AD. Key evidence linking diabetes to AD emphasizes critical metabolic processes that contribute to neurodegeneration, including inflammation, oxidative stress, and alterations in insulin signaling pathways. By framing AD within this metabolic context, we can enhance our understanding of its etiology, which in turn may influence early diagnosis, treatment plans, and preventive measures. Understanding AD as a manifestation of diabetes opens up the possibility of employing novel therapeutic strategies that incorporate lifestyle modifications and the use of antidiabetic medications to mitigate cognitive decline. This integrated approach has the potential to improve patient outcomes and deepen our comprehension of the intricate relationship between neurodegenerative diseases and metabolic disorders.

Zebrafish as a model organism to study sporadic Alzheimer's disease: Behavioural, biochemical and histological validation

Alzheimer's disease (AD) is a global burden to the healthcare system with no viable treatment options till date. Rodents and primates have been extensively used as models for understanding AD pathogenesis and identifying therapeutic targets. However, the focus is now shifting towards developing alternate models. Zebrafish is emerging as a preferred model for neurodegenerative conditions because of its simple nervous system, highly conserved genome and short duration required to model disease condition. The present study is aimed to develop streptozotocin (STZ)-induced model of sporadic AD (sAD) in zebrafish. STZ was administered to adult zebrafish (4-6 mo) at different doses (1 to 50 mg/kg body weight, intracerebroventricularly). Kaplan-Meier survival analysis revealed time and dose dependent mortality in the zebrafish administered with STZ. Based on survival analysis, 1 to 10 mg/kg body weight of STZ was selected for behavioural, molecular and histological studies. STZ administered fish had anxiety and stress-like behaviour in novel tank and light/dark preference tests. STZ-induced cognitive and memory deficits assessed using novel object recognition and spatial alternation tests. Further, expression of markers of amyloidogenic pathway (appa and bace1) were increased in terms of mRNA and protein levels in a time and dose dependent manner following STZ administration. However, expression of non-amyloidogenic pathway mediator (adam10) was reduced at both mRNA and protein level. Histological assessment using hematoxylin and eosin, and Nissl stain revealed loss of neurons in STZ administered fish. The ratio of phosphor-tauser396/total-tau was increased in STZ administered fish. Based on these findings, 5 mg/kg body weight of STZ was found to be most appropriate dose to exhibit sAD phenotype. Mass spectrometric analysis confirmed the presence of amyloid beta oligomers in brains of STZ administered fish. Transmission electron microscopy also showed the presence of higher order insoluble amyloid fibrils with twists. Immunohistochemical analysis revealed amyloid beta deposits in brain of STZ administered fish. Golgi-cox staining indicated decreased number of dendrites, whereas microglia had increased density, span ratio, soma area and lacunarity. The results of the present study demonstrate presence of AD hallmarks and phenotype in zebrafish 7 days post STZ administration (5 mg/kg). The study validates the potential of STZ-induced sAD in zebrafish as a reliable model for studying pathophysiology and rapid screening of therapeutic molecules against sAD.

Positive association of the anti-aging protein α-Klotho with insulin resistance and its inverse L-shaped relationship with glycaemic control in the middle-aged and elderly population

PURPOSE

α-Klotho has been linked to insulin resistance (IR) in basic research. However, experimental evidence is inconsistent, and there is a lack of data from human research. This study seeks to elucidate the association of α-Klotho with IR in a nationwide, multiracial population.

METHODS

A total of 5289 participants aged 40-79 years were included in the National Health and Nutrition Examination Survey (NHANES) spanning 2007-2016. Serum α-Klotho was measured using enzyme-linked immunosorbent assays (ELISA), and IR was evaluated by the homeostatic model assessment of insulin resistance (HOMA-IR). Weighted multivariate logistic and linear regression analysis, subgroup analysis stratified by demographic characteristics, medical condition or obesity status, and sensitivity analysis using propensity score matching (PSM) were performed. Restricted cubic splines (RCS) were performed to explore the nonlinear relationship.

RESULTS

In the fully adjusted logistic regression model, a significant positive association was observed between log-transformed α-Klotho and IR (OR = 3.63, 95% CI: 1.56, 8.45), particularly in males or nonobese individuals (Pinteraction < 0.05). In the linear regression model, log10(α-Klotho) was associated with fasting blood glucose (FBG, β = 1.25, 95% CI: 0.74, 1.76) and glycosylated hemoglobin (HbA1c, β = 0.49, 95% CI: 0.20, 0.77). RCS revealed an inverse L-shaped dose-response relationship of α-Klotho with FBG and HbA1c (Pnonlinear <0.05). Beyond the inflection point of log10(α-Klotho) at 2.79, β coefficients sharply rose for these glycaemic control indicators.

CONCLUSION

The study provides clinical evidence supporting a positive association between α-Klotho and IR. Moreover, the inverse L-shaped relationship suggests that α-Klotho should reach a certain level to predict glycaemic changes effectively.

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.

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.

Banxia Xiexin Decoction Alleviated Cerebral Glucose Metabolism Disorder by Regulating Intestinal Microbiota in APP/PS1 Mice

OBJECTIVE

To identify whether Banxia Xiexin Decoction (BXD) alleviates cerebral glucose metabolism disorder by intestinal microbiota regulation in APP/PS1 mice.

METHODS

Forty-five 3-month-old male APP/PS1 mice were divided into 3 groups using a random number table (n=15 per group), including a model group (MG), a liraglutide group (LG) and a BXD group (BG). Fifteen 3-month-old male C57BL/6J wild-type mice were used as the control group (CG). Mice in the BG were administered BXD granules by gavage at a dose of 6 g/(kg•d) for 3 months, while mice in the LG were injected intraperitoneally once daily with Liraglutide Injection (25 nmol/kg) for 3 months. Firstly, liquid chromatography with tandem-mass spectrometry was used to analyze the active components of BXD granules and the medicated serum of BXD. Then, the cognitive deficits, Aβ pathological change and synaptic plasticity markers, including synaptophysin (SYP) and postsynaptic density protein 95 (PSD95), were measured in APP/PS1 mice. Brain glucose uptake was detected by micropositron emission tomography. Intestinal microbial constituents were detected by 16S rRNA sequencing. The levels of intestinal glucagon-like peptide 1 (GLP-1) and cerebral GLP-1 receptor (GLP-1R), as well as the phosphoinositide-3-kinase/protein kinase B/glycogen synthase kinase-3β (PI3K/Akt/GSK3β) insulin signaling pathway were determined by immunohistochemical (IHC) staining and Western blot analysis, respectively.

RESULTS

BXD ameliorated cognitive deficits and Aβ pathological features (P<0.01). The expressions of SYP and PSD95 in the BG were higher than those in the MG (P<0.01). Brain glucose uptake in the BG was higher than that in the MG (P<0.01). The intestinal microbial composition in the BG was partially reversed. The levels of intestinal GLP-1 in the BG were higher than those in the MG (P<0.01). Compared with the MG, the expression levels of hippocampal GLP-1R, Akt, PI3K and p-PI3K in the BG were significantly increased (P<0.01), while the levels of GSK3β were reduced (P<0.01).

CONCLUSION

BXD exhibited protective effects against Alzheimer's disease by regulating the gut microbiota/GLP-1/GLP-1R, enhancing PI3K/Akt/GSK3β insulin signaling pathway, and improving brain glucose metabolism.

Age-dependent impact of streptozotocin on metabolic endpoints and Alzheimer's disease pathologies in 3xTg-AD mice

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease with a complex origin, thought to involve a combination of genetic, biological and environmental factors. Insulin dysfunction has emerged as a potential factor contributing to AD pathogenesis, particularly in individuals with diabetes, and among those with insulin deficiency or undergoing insulin therapy. The intraperitoneal administration of streptozotocin (STZ) is widely used in rodent models to explore the impact of insulin deficiency on AD pathology, although prior research predominantly focused on young animals, with no comparative analysis across different age groups. Our study aimed to fill this gap by analyzing the impact of insulin dysfunction in 7 and 23 months 3xTg-AD mice, that exhibit both amyloid and tau pathologies. Our objective was to elucidate the age-specific consequences of insulin deficiency on AD pathology. STZ administration led to insulin deficiency in the younger mice, resulting in an increase in cortical amyloid-β (Aβ) and tau aggregation, while tau phosphorylation was not significantly affected. Conversely, older mice displayed an unexpected resilience to the peripheral metabolic impact of STZ, while exhibiting an increase in both tau phosphorylation and aggregation without significantly affecting amyloid pathology. These changes were paralleled with alterations in signaling pathways involving tau kinases and phosphatases. Several markers of blood-brain barrier (BBB) integrity declined with age in 3xTg-AD mice, which might have facilitated a direct neurotoxic effect of STZ in older mice. Overall, our research confirms the influence of insulin signaling dysfunction on AD pathology, but also advises careful interpretation of data related to STZ-induced effects in older animals.

Metabolism changes caused by glucose in normal and cancer human brain cell lines by Raman imaging and chemometric methods

Glucose is the main source of energy for the human brain. This paper presents a non-invasive technique to study metabolic changes caused by glucose in human brain cell lines. In this paper we present the spectroscopic characterization of human normal brain (NHA; astrocytes) and human cancer brain (CRL-1718; astrocytoma and U-87 MG; glioblastoma) control cell lines and cell lines upon supplementation with glucose. Based on Raman techniques we have identified biomarkers that can monitor metabolic changes in lipid droplets, mitochondria and nucleus caused by glucose. We have studied the vibrations at 750 cm-1, 1444 cm-1, 1584 cm-1 and 1656 cm-1 as a function of malignancy grade. We have compared the concentration of cytochrome, lipids and proteins in the grade of cancer aggressiveness in normal and cancer human brain cell lines. Chemometric analysis has shown that control normal, control cancer brain cell lines and normal and cancer cell lines after supplementation with glucose can be distinguished based on their unique vibrational properties. PLSDA (Partial Least Squares Discriminant Analysis) and ANOVA tests have confirmed the main role of cytochromes, proteins and lipids in differentiation of control human brain cells and cells upon supplementation with glucose. We have shown that Raman techniques combined with chemometric analysis provide additional insight to monitor the biology of astrocytes, astrocytoma and glioblastoma after glucose supplementation.

Essential New Complexity-Based Themes for Patient-Centered Diagnosis and Treatment of Dementia and Predementia in Older People: Multimorbidity and Multilevel Phenomenology

Dementia is a highly prevalent condition with devastating clinical and socioeconomic sequela. It is expected to triple in prevalence by 2050. No treatment is currently known to be effective. Symptomatic late-onset dementia and predementia (SLODP) affects 95% of patients with the syndrome. In contrast to trials of pharmacological prevention, no treatment is suggested to remediate or cure these symptomatic patients. SLODP but not young onset dementia is intensely associated with multimorbidity (MUM), including brain-perturbating conditions (BPCs). Recent studies showed that MUM/BPCs have a major role in the pathogenesis of SLODP. Fortunately, most MUM/BPCs are medically treatable, and thus, their treatment may modify and improve SLODP, relieving suffering and reducing its clinical and socioeconomic threats. Regrettably, the complex system features of SLODP impede the diagnosis and treatment of the potentially remediable conditions (PRCs) associated with them, mainly due to failure of pattern recognition and a flawed diagnostic workup. We suggest incorporating two SLODP-specific conceptual themes into the diagnostic workup: MUM/BPC and multilevel phenomenological themes. By doing so, we were able to improve the diagnostic accuracy of SLODP components and optimize detecting and favorably treating PRCs. These revolutionary concepts and their implications for remediability and other parameters are discussed in the paper.

Insulin resistance as the molecular link between diabetes and Alzheimer's disease

Diabetes mellitus (DM) and Alzheimer's disease (AD) are two major health concerns that have seen a rising prevalence worldwide. Recent studies have indicated a possible link between DM and an increased risk of developing AD. Insulin, while primarily known for its role in regulating blood sugar, also plays a vital role in protecting brain functions. Insulin resistance (IR), especially prevalent in type 2 diabetes, is believed to play a significant role in AD's development. When insulin signalling becomes dysfunctional, it can negatively affect various brain functions, making individuals more susceptible to AD's defining features, such as the buildup of beta-amyloid plaques and tau protein tangles. Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD. This review aims to explore the rela-tionship between DM and AD, with a focus on the role of IR. It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR. Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.

Insulin Resistance/Hyperinsulinemia as an Independent Risk Factor That Has Been Overlooked for Too Long

Unfortunately, cardiovascular diseases and cancers are still the leading causes of death in developed and developing countries despite the considerable progress made in the prevention and treatment of diseases. Maybe we missed something? Insulin resistance (IR) with associated hyperinsulinemia (Hypein) is a silent pandemic whose prevalence is continually growing in developed and developing countries, now exceeding 51% of the general population. IR/Hypein, despite the vast scientific literature supporting its adverse action on the development of type 2 diabetes, cardiovascular alterations, tumors, neurological disorders, and cellular senescence, is not yet considered an independent risk factor and, therefore, is not screened in the general population and adequately treated. There are now numerous substances, drugs, and natural substances that, in association with the correction of a wrong lifestyle, can help to reduce IR/Hypein. We are convinced that the time has come to implement a prevention plan against this critical risk factor. Therefore, this manuscript aims to highlight IR/Hypein as an independent risk factor for type 2 diabetes, cardiovascular diseases, cancers, cellular senescence, and neuropsychiatric disorders, supporting our conviction with the available scientific literature on the topic.

Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance

Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, ??mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.

Gluco-regulation & type 2 diabetes: entrenched misconceptions updated to new governing principles for gold standard management

Our understanding of type 2 diabetes (T2D) has evolved dramatically. Advances have upended entrenched dogmas pertaining to the onset and progression of T2D, beliefs that have prevailed from the early era of diabetes research-and continue to populate our medical textbooks and continuing medical education materials. This review article highlights key insights that lend new governing principles for gold standard management of T2D. From the historical context upon which old beliefs arose to new findings, this article outlines evidence and perspectives on beta cell function, the underlying defects in glucoregulation, the remediable nature of T2D, and, the rationale supporting the shift to complication-centric prescribing. Practical approaches translate this rectified understanding of T2D into strategies that fill gaps in current management practices of prediabetes through late type 2 diabetes.

Proteomic Analysis of a Rat Streptozotocin Model Shows Dysregulated Biological Pathways Implicated in Alzheimer's Disease

Alzheimer's Disease (AD) is an age-related neurodegenerative disorder characterized by progressive memory loss and cognitive impairment, affecting 35 million individuals worldwide. Intracerebroventricular (ICV) injection of low to moderate doses of streptozotocin (STZ) in adult male Wistar rats can reproduce classical physiopathological hallmarks of AD. This biological model is known as ICV-STZ. Most studies are focused on the description of behavioral and morphological aspects of the ICV-STZ model. However, knowledge regarding the molecular aspects of the ICV-STZ model is still incipient. Therefore, this work is a first attempt to provide a wide proteome description of the ICV-STZ model based on mass spectrometry (MS). To achieve that, samples from the pre-frontal cortex (PFC) and hippocampus (HPC) of the ICV-STZ model and control (wild-type) were used. Differential protein abundance, pathway, and network analysis were performed based on the protein identification and quantification of the samples. Our analysis revealed dysregulated biological pathways implicated in the early stages of late-onset Alzheimer's disease (LOAD), based on differentially abundant proteins (DAPs). Some of these DAPs had their mRNA expression further investigated through qRT-PCR. Our results shed light on the AD onset and demonstrate the ICV-STZ as a valid model for LOAD proteome description.

Association of Vitamin D Levels with Risk of Cognitive Impairment and Dementia: A Systematic Review and Meta-Analysis of Prospective Studies

Background

Emerging evidence suggests the potential relationship between vitamin D deficiency and risk of cognitive impairment or dementia. To what extent the excess risk of dementia conferred by vitamin D deficiency is less clear.

Objective

We summarized the current evidence from several aspects and further quantified these associations.

Methods

We collected relevant prospective cohort studies by searching PubMed, Embase and Cochrane up to July 2023. The pooled relative risks (RR) were evaluated by random-effects models. Dose-response analyses were conducted by the method of two-stage generalized least squares regression.

Results

Of 9,267 identified literatures, 23 were eligible for inclusion in the meta-analyses, among which 9 and 4 literatures were included in the dose-response analyses for the risk of dementia and Alzheimer's disease (AD). Vitamin D deficiency exhibited a 1.42 times risk for dementia (95% confidence interval (CI) = 1.21-1.65) and a 1.57-fold excess risk for AD (95% CI = 1.15-2.14). And vitamin D deficiency was associated with 34% elevated risk with cognitive impairment (95% CI = 1.19-1.52). Additionally, vitamin D was non-linearly related to the risk of dementia (pnonlinearity = 0.0000) and AD (pnonlinearity = 0.0042). The approximate 77.5-100 nmol/L 25-hydroxyvitamin D [25(OH)D] was optimal for reducing dementia risk. And the AD risk seemed to be decreased when the 25(OH)D level >40.1 nmol/L.

Conclusions

Vitamin D deficiency was a risk factor for dementia, AD, and cognitive impairment. The nonlinear relationships may further provide the optimum dose of 25(OH)D for dementia prevention.

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.

Disease-associated astrocytes and microglia markers are upregulated in mice fed high fat diet

High-fat diet (HFD) is associated with Alzheimer's disease (AD) and type 2 diabetes risk, which share features such as insulin resistance and amylin deposition. We examined gene expression associated with astrocytes and microglia since dysfunction of these cell types is implicated in AD pathogenesis. We hypothesize gene expression changes in disease-associated astrocytes (DAA), disease-associated microglia and human Alzheimer's microglia exist in diabetic and obese individuals before AD development. By analyzing bulk RNA-sequencing (RNA-seq) data generated from brains of mice fed HFD and humans with AD, 11 overlapping AD-associated differentially expressed genes were identified, including Kcnj2, C4b and Ddr1, which are upregulated in response to both HFD and AD. Analysis of single cell RNA-seq (scRNA-seq) data indicated C4b is astrocyte specific. Spatial transcriptomics (ST) revealed C4b colocalizes with Gfad, a known astrocyte marker, and the colocalization of C4b expressing cells with Gad2 expressing cells, i.e., GABAergic neurons, in mouse brain. There also exists a positive correlation between C4b and Gad2 expression in ST indicating a potential interaction between DAA and GABAergic neurons. These findings provide novel links between the pathogenesis of obesity, diabetes and AD and identify C4b as a potential early marker for AD in obese or diabetic individuals.

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

The Expression of Insulin in the Central Nervous System: What Have We Learned So Far?

After being discovered over a century ago, insulin was long considered to be a hormone exclusively produced by the pancreas. Insulin presence was later discovered in the brain, which was originally accounted for by its transport across the blood-brain barrier. Considering that both insulin mRNA and insulin were detected in the central nervous system (CNS), it is now known that this hormone is also synthesized in several brain regions, including the hypothalamus, hippocampus, cerebral and cerebellar cortex, and olfactory bulb. Although many roles of insulin in the CNS have been described, it was initially unknown which of them could be attributed to brain-derived and which to pancreatic insulin or whether their actions in the brain overlap. However, more and more studies have been emerging lately, focusing solely on the roles of brain-derived insulin. The aim of this review was to present the latest findings on the roles of brain-derived insulin, including neuroprotection, control of growth hormone secretion, and regulation of appetite and neuronal glucose uptake. Lastly, the impairment of signaling initiated by brain-derived insulin was addressed in regard to memory decline in humans.