Search Results (287)

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder marked by amyloid-β (Aβ) plaques, neurofibrillary tangles, blood–brain barrier dysfunction, oxidative stress (OS), and neuroinflammation. Current treatments provide symptomatic relief, but do not halt the disease’s progression. OS plays a crucial role in AD pathogenesis by promoting Aβ accumulation. Nuclear factor erythroid 2-related factor 2 (NRF2) is a key regulator of the antioxidant response, influencing genes involved in OS mitigation, mitochondrial function, and inflammation. Dysregulation of NRF2 is implicated in AD, making it a promising therapeutic target. Emerging evidence suggests that adherence to a Mediterranean diet (MD), which is particularly rich in polyphenols from extra virgin olive oil (EVOO), is associated with improved cognitive function and a reduced risk of mild cognitive impairment. Polyphenols can activate NRF2, enhancing endogenous antioxidant defenses. This study employs a computational approach to explore the potential of bioactive compounds in EVOO to modulate NRF2-related pathways in AD. We analyzed transcriptomic data from AD and EVOO-treated samples to identify NRF2-associated genes, and used chemical structure-based analysis to compare EVOO’s bioactive compounds with known NRF2 activators. Enrichment analysis was performed to identify common biological functions between NRF2-, EVOO-, and AD-related pathways. Our findings highlight important factors and biological functions that provide new insight into the molecular mechanisms through which EVOO consumption might influence cellular pathways associated with AD via modulation of the NRF2 pathway. The presented approach provides a different perspective in the discovery of compounds that may contribute to neuroprotective mechanisms in the context of AD. Full article

Alzheimer’s disease (AD) is the most common cause of cognitive decline. Among the various susceptibility genes, the gene of apolipoprotein E (APOE) is probably the most important. It may be present in three allelic forms, termed ε2, ε3 and ε4, and the most common genotype is the ε3/ε3. Recently, it has been observed that subjects with the ε4/ε4 genotype may show near-full penetrance of AD biology (pathology and biomarkers), leading to the suggestion that ε4 homozygosity may represent a distinct genetic type of AD. The aim of the present study was to investigate the role of ε4 homozygosity or heterozygosity in the presence or absence of the AD biomarker profile in patients with cognitive disorders in the Greek population. A total of 274 patients were included in the study. They underwent APOE genotyping and cerebrospinal fluid (CSF) biomarker profiling. The presence of ε4 was associated with a lower age of symptom onset and decreased amyloid biomarkers (irrespective to AD or non-AD profiles), and predicted the presence of an AD profile by a positive predictive value approaching 100%. In conclusion, the ε4 allele has a significant effect on the risk and clinical parameters of cognitive impairment and AD in the Greek population, while the ε4/ε4 genotype may be highly indicative of the (co)existence of AD in cognitively impaired patients. Full article

Alzheimer’s disease (AD) and ischemic stroke (IS) are prevalent neurological disorders that frequently co-occur in the same individuals. Recent studies have demonstrated that AD and IS share several common risk factors and pathogenic elements, including an overlapping genomic architecture. However, the relationship between IS risk gene polymorphisms and AD has been less extensively studied. We aimed at determining whether IS risk gene polymorphisms were associated with the risk of AD and the severity of AD in AD patients. We utilized data of AD patients and normal controls (NCs) sourced from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort. IS risk single nucleotide polymorphisms (SNPs) were identified through the most recent and largest IS genome-wide association study (GWAS) meta-analysis. Subsequently, we conducted SNP-based association analysis of IS-risk SNPs with the risk of AD, along with amyloid, tau, and neuroimaging for AD. The generalized multifactor dimensionality reduction (GMDR) model was used to assess the interactions among IS-risk SNPs and apolipoprotein E (ApoE) ε4. Protein–protein interactions (PPIs) of the IS-risk genes product and APOE were explored using the STRING database. Seven IS-risk SNPs were involved in the study. Five SNPs were found to be associated with at least one measurement of cerebrospinal fluid (CSF) levels of amyloid-beta 1–42 (Aβ₄₂), total tau (t-tau), and phosphorylated tau 181 (p-tau₁₈₁), as well as the volumes of the hippocampus, whole brain, entorhinal cortex, and mid-temporal regions. After multiple testing corrections, we found that T allele of rs1487504 contributed to an increased risk of AD in non-ApoE ε4 carriers. The combination of rs1487504 and ApoE ε4 emerged as the optimal two-factor model, and its interaction was significantly related to the risk of AD. Additionally, C allele of rs880315 was significantly associated with elevated levels of CSF Aβ₄₂ in AD patients, and A allele of rs10774625 was significantly related to a reduction in the volume of the entorhinal cortex in AD patients. This study found that IS risk SNPs were associated with both the risk of AD and AD major indicators in the ADNI cohort. These findings elucidated the role of IS in AD from a genetic perspective and provided an innovative approach to predict AD through IS-risk SNPs. Full article

Alzheimer’s disease (AD) is a progressive, complex, multifactorial, neurodegenerative disease and accounts for most cases of dementia. The currently approved therapy includes cholinesterase inhibitors, NMDA-receptor antagonists and monoclonal antibodies. However, these medications were gradually discovered to be ineffective in removing the root of AD pathogenesis, having only symptomatic effects. Thus, the priority remains prevention and clarifying AD etiology. A better understanding of the neuroprotective mechanisms undertaken by specific genes is crucial to guide the design of novel therapeutic agents via selective ligands and precision medicine. In this review, we present a perspective of the physiological phase of the AD spectrum, of risk factors in AD with a focus on therapeutic approaches in three categories: neurotransmitters/ion modulations, peptide deposit control and aspecific treatments, followed by a discussion of treatment limitations. An overview of innovative strategies and non-pharmaceutical ancillary support is given. Full article

Insulin-degrading enzyme (IDE) plays a critical role in regulating insulin levels in various tissues, including the brain, liver, and kidneys. In type 2 diabetes mellitus (T2DM), key features include insulin resistance, elevated insulin levels in the blood, and hyperglycemia. In this context, the function of IDE becomes particularly important; however, in T2DM, IDE’s function can be impaired. Notably, individuals with T2DM have a higher risk of developing Alzheimer’s disease (AD), suggesting that impaired IDE function may contribute to both diabetes and neurodegeneration. IDE has been studied for its ability to degrade Amyloid-β peptides, the primary constituents of amyloid plaques in AD. However, its role in Aβ clearance in vivo remains debated due to limited enzymatic efficacy under physiological conditions and differences in subcellular localization between IDE and its putative substrate. Other proteases, such as neprilysin, appear to play a more prominent role in preventing plaque formation. Additionally, the long-standing hypothesis that insulin competes with Aβ for IDE activity has been questioned, as brain insulin levels are too low to inhibit Aβ degradation significantly. Genetic variants in the IDE gene have been associated with increased AD risk, although the mechanisms by which they alter enzyme function are not yet fully understood. A deeper understanding of IDE’s role in the context of both metabolic and neurodegenerative diseases may provide valuable insights for the development of new therapeutic strategies. Full article

Background: Research concerning the genetic risk for dementia has recently been headed towards new directions. Novel findings from genome-wide association studies have highlighted the association of Alzheimer’s disease incidence with many gene polymorphisms, apart from the Apolipoprotein-E genotype. The identification of additional genetic risk factors has led to the construction of specific genetic risk scores for dementia, considering many different genetic factors and specific biological pathways related to Alzheimer’s disease. Methods: We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis method, summarizing existing data regarding genetic risk scores for Alzheimer’s disease and dementia, in order to improve the current understanding of the genetic underpinnings of dementia. In specific, five databases (PubMed/MEDLINE, Embase, Scopus, Web of science, and Cochrane Central) were searched using the keywords “genetic risk score”, “Alzheimer’s disease”, and “dementia” with specific inclusion and exclusion criteria. Results: From the 552 articles identified, we finally included 20 studies for the qualitative analysis. These reports were classified in three different categories of genetic scores: “polygenic risk scores (PRSs)” (including 11 studies), “pathway specific polygenic risk scores (p-PRSs)” (5 studies), and “complex genetic risk scores” (4 studies). Conclusions: Existing genetic risk scores have contributed to better dementia prediction and a better understanding of the underlying pathology. Novel approaches integrating multiple polygenic risk scores might ameliorate the accuracy of genetic risk scores. The combination of polygenic risk scores that are specific to related biological pathways or relevant biomarkers is of utmost importance to achieve a better predictive ability. Full article

Network-based GWAS (NetWAS) has advanced brain imaging research by identifying genetic modules associated with brain alterations. However, how imaging risk genes exert functions in brain diseases, particularly their mediation through imaging quantitative traits (iQTs), remains underexplored. We propose a module-level polygenic risk score (MPRS)-based NetWAS framework to uncover genetic modules associated with Alzheimer’s disease (AD) through the mediation of an iQT, using amygdala density as a case study. Our framework integrates genotype data, brain imaging phenotypes, clinical diagnosis of AD, and protein–protein interaction (PPI) networks to identify AD-relevant modules (ADMs) influenced by iQT-associated genetic variants. Specifically, we conducted a genome-wide association study (GWAS) of amygdala density ($N=1515$) to identify variants associated with iQT. These variants were mapped onto a PPI network and network propagation was performed to prompt amygdala modules. The meta-GWAS of AD ($N_1=63,926$; $N_2=455,267$) was used to calculate MPRS to further identify AD-relevant modules (ADMs). Four modules that showed significant differences in MPRS between AD and controls were identified as ADM. Post-hoc analyses revealed that these ADMs demonstrated strong modularity, showed increased sensitivity to early stages of AD, and significantly mediated the link between ADMs and AD progression through the amygdala. Furthermore, these modules exhibited high tissue specificity within the amygdala and were enriched in AD-related biological pathways. Our MPRS-based framework bridges genetics, intermediate traits, and clinical outcomes and can be adapted for broader biomedical applications. Full article

Oxidative stress has become a common impetus of various diseases, including neurodegenerative diseases. This review introduces the generation of reactive oxygen species (ROSs) in the nervous system, the cellular oxidative damage, and the high sensitivity of the brain to ROSs. The literature review focuses on the roles of oxidative stress in neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS). Oxidative stress occurs when excessively produced free radicals are beyond the capability of endogenous antioxidants to scavenge, leading to the oxidation of proteins, lipids, and nucleic acids, stimulating neuroinflammatory responses, causing neuronal dysfunction, senescence, and death. The dysfunctional mitochondria and aberrant activities of metabolic enzymes are the major source of ROSs. The high vulnerability of the nervous system to ROSs underlies the critical roles of oxidative stress in neurodegenerative diseases. Gene mutations and other risk factors promote the generation of ROSs, which have been considered a crucial force causing the main pathological features of AD, PD, HD, and ALS. As a result, antioxidants hold therapeutic potential in these neurodegenerative diseases. The elucidation of the pathogenic mechanisms of oxidative stress will facilitate the development of antioxidants for the treatment of these diseases. Full article

Little is known about the dysbiosis of the gut microbiome in patients with mild cognitive impairment (MCI) potentially at risk for the development of Alzheimer’s disease (AD). So far, only cross-sectional differences and not longitudinal changes and their prognostic significance have been in the scope of research in MCI. Therefore, we investigated the ability of longitudinal taxonomic and functional gut microbiome data from 100 healthy controls (HC) to predict the progression from normal cognition to MCI over a 4-year follow-up period (4yFU). Logistic regression models were built with baseline features that best discriminated between the two groups using an ANOVA-type statistical analysis. The best model for the discrimination of MCI converters was based on functional data using Gene Ontology (GO), which included 14 features. This model achieved an area under the receiver operating characteristic curve (AUROC) of 0.84 at baseline, 0.78 at the 1-year follow-up (1yFU), and 0.75 at 4yFU. This functional model outperformed the taxonomic model, which included 38 genera features, in terms of descriptive performance and showed comparable efficacy to combined analyses integrating functional, taxonomic, and clinical characteristics. Thus, gut microbiome algorithms have the potential to predict MCI conversion in HCs over a 4-year period, offering a promising innovative supplement for early AD identification. Full article

Background/Objectives: Several genetic factors are related to the risk of Alzheimer’s disease (AD) and the response to cholinesterase inhibitors (ChEIs) (donepezil, galantamine, and rivastigmine) or memantine. However, findings have been controversial, and, to the best of our knowledge, admixed populations have not been previously evaluated. We aimed to determine the impact of genetic and non-genetic factors on the risk of AD and the short-term response to ChEIs and memantine in patients with AD from Mexico. Methods: This study included 117 patients from two specialty hospitals in Mexico City, Mexico. We evaluated cognitive performance via clinical evaluations and neuropsychological tests. Nineteen variants in ABCB1, ACHE, APOE, BCHE, CHAT, CYP2D6, CYP3A5, CHRNA7, NR1I2, and POR were assessed through TaqMan assays or PCR. Results: Minor alleles of the ABCB1 rs1045642, ACHE rs17884589, and CHAT rs2177370 and rs3793790 variants were associated with the risk of AD; meanwhile, CHRNA7 rs6494223 and CYP3A5 rs776746 were identified as low-risk variants in AD. BCHE rs1803274 was associated with worse cognitive functioning. None of the genetic and non-genetic factors studied were associated with the response to pharmacological treatment. Conclusions: We identified potential genetic variants related to the risk of AD; meanwhile, no factor was observed to impact the response to pharmacological therapy in patients with AD from Mexico. Full article

Background: Comorbidities such as hypertension and hypercholesterolemia are risk factors associated with Mild Cognitive Impairment (MCI) and Alzheimer’s disease (AD). The most significant genetic risk factor is the ε4 allele of the apolipoprotein E gene (APOE). The aim of this paper is to determine whether hypertension is the most significant but modifiable risk factor to delay AD onset. Method: A cohort of patients with MCI (N = 3052) is developed from the documented database (N = 43,999) within the National Alzheimer’s Coordinating Center (NACC) during the time period from June 2005 to May 2021. Cox proportional hazard models with propensity score weights on demographic information and comorbidities at baseline are applied to examine association of hypertension and hypercholesterolemia with AD onset among MCI patients. Associations are compared to APOE genotypes and AD onset. In addition, the association of hypertension with decline rates in Mini-Mental State Examination (MMSE) scores are reported. Results: After controlling for age, sex, race, APOEε4, and reported comorbidities, the results show that MCI patients who subsequently develop hypertension within 18 months after their first diagnosis of MCI have a significantly higher risk of AD onset (HR = 2.77, 95%CI (1.66, 4.65), p value < 0.0001), compared to MCI patients with no hypertension or a late occurrence of hypertension after 18 months. This significant association is validated through a Random Forest method, a machine learning approach with bootstrap simulations. In addition, patients with early hypertension have significantly higher MMSE score declining rates compared to those without hypertension (coefficient = 0.988, p = 0.0054.). Conclusions: Hypertension is the most significant risk factor comparable to the genetic risk factor APOEε4 allele. Our finding is unique, as we did not observe a similar outcome in those with early hypercholesterolemia. Thus, among all comorbidities, hypertension is the most significant risk factor similar to the genetic risk factor APOEε4 allele. Full article

Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have emerged as a promising therapeutic option beyond their established role in managing type 2 diabetes mellitus (T2DM) and obesity. Recent research has highlighted their beneficial effects on liver, kidney, and cardiovascular health, mediated by both direct and indirect mechanisms. In the liver, GLP-1 RAs contribute to the improvement of metabolic dysfunction-associated steatotic liver disease (MASLD) by reducing hepatic fat accumulation, inflammation, and oxidative stress. Additionally, they enhance insulin sensitivity and lipid metabolism. Similarly, in diabetic kidney disease (DKD), GLP-1 RAs exhibit renoprotective properties by mitigating inflammation, oxidative stress, and glomerular hypertension. Furthermore, they promote natriuresis and stabilize renal function. Moreover, GLP-1 RAs present significant cardiovascular benefits, including improved myocardial function, reduced atherosclerosis progression, enhanced endothelial health, and decreased major adverse cardiovascular events (MACEs). Additionally, emerging evidence suggests GLP-1 RAs may exert substantial neuropsychiatric benefits, including reductions in depressive symptoms, anxiety, substance use behaviors, and lowering the risk of Alzheimer’s disease, Parkinson’s disease, and other dementias likely mediated by the modulation of neurotransmitter systems and neuroinflammation. Genetic polymorphisms in the GLP1R gene also impact the therapeutic response, highlighting the importance of personalized medicine in optimizing GLP-1 RA efficacy. This review synthesizes preclinical and clinical evidence supporting the multifaceted effects of GLP-1 RAs across multiple organ systems, highlighting their therapeutic potential beyond glycemic control. As research advances, further exploration of their mechanisms of action and long-term clinical outcomes, safety and effectiveness across diverse patient populations will be essential in optimizing their use in treating metabolic and neuropsychiatric conditions. Full article

Metabolic disorders and brain insulin resistance (IR) are major risk factors for the development of neurodegenerative conditions. Kumquat fruit (KF) administration has demonstrated significant anti-dysmetabolic effects, improving peripheral IR in murine models of metabolic syndrome. Along these lines, this study evaluated the neuroprotective effects of KF supplementation in a model of dysmetabolism-induced neuronal damage and its ability to counteract the disruption of brain insulin signalling. To this end, biochemical and histological analysis assessed neuroapoptosis, disruption of brain insulin signalling and neuroinflammation in a model of high-fat diet (HFD)-induced neuronal damage. Our findings demonstrate, for the first time, that KF supplementation significantly counteracts HFD-induced neuroapoptosis downregulating pro-apoptotic genes (FAS-L, BIM and P27) and upregulating the anti-apoptotic ones (BDNF and BCL-2). Coherently, KF positively influenced the expression of selected genes related to Alzheimer’s Disease. Relevantly, these effects were associated to KF ability to restore brain insulin signalling by increasing insulin receptor expression, reducing IRS-1 serine phosphorylation, enhancing both AKT activation and GSK-3β inactivation. Accordingly, KF suppressed HFD-neuroinflammation, counteracting the overexpression of NF-κB and its downstream enzymatic products, iNOS and COX-2. Collectively, these findings demonstrate the neuroprotective benefits of KF administration, supporting its potential as a dietary intervention for dysmetabolic-related neurodegenerative disorders. Full article

Background: The synonymous variant NC_000007.14:g.100373690T>C (rs2405442:T>C) in the Paired Immunoglobulin-like Type 2 Receptor Alpha (PILRA) gene was previously associated with decreased risk for Alzheimer’s disease (AD) in genome-wide association studies, but its biological impact is largely unknown. Objective: We hypothesized that rs2405442:T>C decreases mRNA and protein levels by destroying a ramp of slowly translated codons at the 5′ end of PILRA. Methods: We assessed rs2405442:T>C predicted effects on PILRA through quantitative polymerase chain reactions (qPCRs) and enzyme-linked immunosorbent assays (ELISAs) using Chinese hamster ovary (CHO) cells. RESULTS: Both mRNA (p = 1.9184 × 10⁻¹³) and protein (p = 0.01296) levels significantly decreased in the mutant versus the wildtype in the direction that we predicted based on the destruction of a ramp sequence. Conclusions: We show that rs2405442:T>C alone directly impacts PILRA mRNA and protein expression, and ramp sequences may play a role in regulating AD-associated genes without modifying the protein product. Full article

The rising prevalence of Alzheimer’s disease (AD), particularly among older adults, has driven increased research into its underlying mechanisms and risk factors. Aging, genetic susceptibility, and cardiovascular health are recognized contributors to AD, but how the age of onset affects disease progression remains underexplored. This study investigates the role of early- versus late-onset Alzheimer’s disease (EOAD and LOAD, respectively) in shaping the trajectory of cognitive decline. Leveraging data from the Religious Orders Study and Memory and Aging Project (ROSMAP), two cohorts were established: individuals with early-onset AD and those with late-onset AD. Comprehensive analyses, including differential gene expression profiling, pathway enrichment, and gene co-expression network construction, were conducted to identify distinct molecular signatures associated with each cohort. Network modularity learning algorithms were used to discern the inner structure of co-expression networks and their related functional features. Computed network descriptors provided deeper insights into the influence of age at onset on the biological progression of AD. Full article