Current Alzheimer Research - Volume 22, Issue 10, 2025
Volume 22, Issue 10, 2025
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Unveiling Role of Gut Microbiota in Alzheimer’s Disease: Mechanisms, Challenges and Future Perspectives
More LessAlzheimer's disease (AD) is a neurodegenerative condition characterized by neuroinflammation, tau hyperphosphorylation, Aβ (Amyloid beta) accumulation, and synaptic dysfunction. New research indicates that the gut-brain axis, a network of two-way communication that involves immunological signals, neural pathways, and microbial metabolites, makes dysbiosis of the gut microbiota essential to the pathogenesis of AD. Alterations in the gut microbiota's composition hinder the production of crucial metabolites, such as short-chain fatty acids, trimethylamine-N-oxide, and secondary bile acids, which affect neuroinflammatory cascades, mitochondrial bioenergetics, and synaptic plasticity. Furthermore, Toll-like receptor 4 -4-mediated microglial responses are triggered by Gram-negative bacterial lipopolysaccharides. This cascade promotes oxidative stress, chronic neuroinflammation, and disruption of the (BBB) blood-brain barrier, all of which encourage the accumulation of neurotoxic proteins. Microbiome-modulating therapies, such as probiotics, prebiotics, and synbiotics, have been shown to have neuroprotective properties. They work by restoring microbial diversity, increasing (Short-chain fatty acids) SCFA-mediated anti-inflammatory pathways, and reducing glial activation. In addition to promoting gut microbiota equilibrium, dietary approaches like the Mediterranean and ketogenic diets, which are enhanced with polyphenols and omega-3 fatty acids, also lower systemic inflammation and increase neural resilience. Furthermore, the potential of postbiotics and fecal microbiota transplantation to attenuate AD-related neurodegeneration and restore gut-derived metabolic balance is being investigated. Translating these methods into standardized clinical applications is difficult, though, because individual microbiome composition varies. It will be essential to address these complications through mechanistic research and extensive clinical trials to establish gut microbiota as a promising therapeutic target in AD.
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Network Pharmacology of miR-146a-5p as a Potential Anti-Inflammatory Agent in Preventing Alzheimer's Disease
More LessAuthors: Sinjye Lee, Jhibiau Foo, Yokekeong Yong, Qihao Daniel Looi and Yinyin OoiIntroductionAlzheimer's disease is expressed as chronic neuroinflammation in the brain, which results in neuronal dysfunction, aberrant protein folding, and declining cognitive abilities. miR-146a-5p is a potent anti-inflammatory agent that can attenuate several inflammatory diseases and promote wound healing. Our research aimed to utilize network pharmacology to elucidate the therapeutic potential of miR-146a-5p in treating Alzheimer's disease using a biocomputational approach.
MethodAlzheimer's disease genes were extracted from DisGeNET, OMIM, and GeneCards databases. At the same time, miR-146a-5p candidate genes were sourced from four prediction databases: miRDB, miRWalk, miRNet, and TargetScan.
ResultsThe overlap between miR-146a-5p and Alzheimer's disease genes was established using STRING, with a score greater than 0.9, revealing a total of 157 nodes in the compound-target disease network.
DiscussionsPathway enrichment analysis further revealed key candidate genes associated with Alzheimer's, including those involved in neuronal death, leukocyte migration, and axon development. EGFR, IL6, NFKB1, TLR4, CXCL8, FN1, CXCR4, and BCL2 were pinpointed as the top 8 key candidate genes of miR-146a-5p. Between these key candidate genes, the miR-146a-5p Regulatory Network also demonstrated that miR-146a-5p downregulates EGFR and CXCR4. Furthermore, this research revealed the regulatory network of miR-146a-5p, which modulates the transcriptional activities of IL6, NFKB1, TLR4, CXCL8, FN1, and BCL2.
ConclusionTherefore, the current network pharmacology study explored the principal mechanism behind the anti-inflammatory effects of miR-146a-5p in treating Alzheimer's disease, and potentially to be applied to other neurodegenerative diseases.
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Arsenic Exposure Induces Cognitive Impairment in Mice with Increased Acetylcholinesterase Activity and Inflammation in the Cortex and Hippocampus: Implications for Alzheimer’s Disease
More LessIntroductionArsenic, a metalloid, is well associated as a risk factor for the development and progression of neurodegenerative diseases, including Alzheimer’s Disease (AD), which is characterized by impairment in cognition. However, specific effects of arsenic on Acetylcholinesterase (AChE) activity and inflammatory markers in different brain regions, as well as its impact on behaviour, are not yet fully understood.
MethodsArsenic was administered (20 mg/kg by gavage for 4 weeks) to male and female mice, and its effects on behaviour were assessed by using the object recognition memory test and light-dark box test. AChE activity and neuronal Nitric Oxide (nNOS) were assessed by histoenzymology, and immunohistochemistry was employed for assessment of Glial Fibrillary Acidic Protein (GFAP).
ResultsBoth the behavioural tests showed significant impairment of learning and memory functions and development of psychiatric abnormalities in arsenic-fed mice. The histoenzymology and immunohistochemistry analysis of the cortex and hippocampus region of these arsenic-fed mice revealed the increment of AChE activity and inflammatory markers, viz. GFAP and nNOS.
DiscussionThe observed increment in AChE activity in the cortex and hippocampus of arsenic-fed mice may contribute to the impairment of learning and memory functions, as well as to the development of psychiatric abnormalities. Furthermore, the enhancement of inflammatory processes in these brain regions may be either a consequence or a contributing factor to the elevated AChE activity, thus establishing a self-fuelling cycle of neuroinflammation and increased AChE activity.
ConclusionGiven the gender bias in neurodegenerative diseases, our findings indicate that arsenic exposure does not lead to significant differences in neuropathological and neurobehavioural outcomes between male and female mice. Moreover, current outcomes underscore the potential of arsenic to act as a neurotoxic agent in AD development.
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Advancing Alzheimer's Disease Diagnosis Using VGG19 and XGBoost: A Neuroimaging-Based Method
More LessAuthors: Abdelmounim Boudi, Jingfei He, Isselmou Abd El Kader, Xiaotong Liu and Mohamed MouhafidIntroductionAlzheimer’s disease (AD) is a progressive neurodegenerative disorder that currently affects over 55 million individuals worldwide. Conventional diagnostic approaches often rely on subjective clinical assessments and isolated biomarkers, limiting their accuracy and early-stage effectiveness. With the rising global burden of AD, there is an urgent need for objective, automated tools that enhance diagnostic precision using neuroimaging data.
MethodsThis study proposes a novel diagnostic framework combining a fine-tuned VGG19 deep convolutional neural network with an eXtreme Gradient Boosting (XGBoost) classifier. The model was trained and validated on the OASIS MRI dataset (Dataset 2), which was manually balanced to ensure equitable class representation across the four AD stages. The VGG19 model was pre-trained on ImageNet and fine-tuned by unfreezing its last ten layers. Data augmentation strategies, including random rotation and zoom, were applied to improve generalization. Extracted features were classified using XGBoost, incorporating class weighting, early stopping, and adaptive learning. Model performance was evaluated using accuracy, precision, recall, F1-score, and ROC-AUC.
ResultsThe proposed VGG19-XGBoost model achieved a test accuracy of 99.6%, with an average precision of 1.00, a recall of 0.99, and an F1-score of 0.99 on the balanced OASIS dataset. ROC curves indicated high separability across AD stages, confirming strong discriminatory power and robustness in classification.
DiscussionThe integration of deep feature extraction with ensemble learning demonstrated substantial improvement over conventional single-model approaches. The hybrid model effectively mitigated issues of class imbalance and overfitting, offering stable performance across all dementia stages. These findings suggest the method’s practical viability for clinical decision support in early AD diagnosis.
ConclusionThis study presents a high-performing, automated diagnostic tool for Alzheimer’s disease based on neuroimaging. The VGG19-XGBoost hybrid architecture demonstrates exceptional accuracy and robustness, underscoring its potential for real-world applications. Future work will focus on integrating multimodal data and validating the model on larger and more diverse populations to enhance clinical utility and generalizability.
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The Comparison Between Dietary Vitamin A Deficiency and the CRP Level in Alzheimer’s Disease in Patients with Type 2 Diabetes: A Case-Control Study
More LessBackgroundType 2 Diabetes Mellitus (T2DM) patients are 50-60% more likely to develop Alzheimer’s Disease (AD). T2DM has many risk factors, including inflammation. Previous studies suggest that CRP was higher in diabetic patients, indicating that it may play a role in diabetogenesis and insulin resistance. Many diseases are prevalent in older age, including T2DM and AD. Moreover, multiple studies suggested a possible association between vitamin A levels, AD, and T2DM. However, the role of Vitamin A in Alzheimer's patients with T2DM has not yet been fully investigated. Therefore, this study aims to measure the association between dietary vitamin A deficiency and AD patients with T2DM in King Abdulaziz Medical City, Jeddah, Western Region, Saudi Arabia, to help expand the preexisting knowledge of the diagnostic risk factors of both the diseases and to determine the significance of vitamin A as a nutritional factor in their management and prevention.
MethodsThis case-control study investigates the prevalence of vitamin A deficiency (VAD) among Alzheimer's disease (AD) patients with and without type 2 diabetes mellitus (T2DM). Participants included 103 AD patients aged 40 and older from the National Guard Hospital in Saudi Arabia, recruited between 2016 and 2022. Data collection occurred in two phases: first, through a review of medical records to gather demographic and health history information, including retrospective blood tests for systemic C-reactive protein (CRP) levels and comorbidities; second, using the HKI Food Frequency Questionnaire (FFQ) to assess dietary intake of vitamin A-rich foods over the past week, with caregiver interviews facilitating this process. Each subject was also prospectively interviewed to assess the presence of VAD events. The study aims to elucidate the relationship between dietary habits and VAD prevalence in AD patients, contributing to the understanding of nutritional impacts on cognitive health in this population.
ResultsThis study examined demographic and clinical characteristics of the Alzheimer’s group, with 70.1% having both Alzheimer's with T2DM and 29.9% having Alzheimer's alone. Significant differences in age were found (p-value = 0.03), but gender distribution was similar (p-value = 0.45). Most caregivers were sons, and 81.43% of patients received oral feeding. Comorbidities included hypertension (94.90%) and dyslipidemia (63.4%), with significant differences (p-value < 0.001). Correlation analyses showed weak negative correlations between CRP and vitamin A concentrations in both groups (Alzheimer with T2DM: p-value = 0.713, rho = -0.064; AD only: p-value = 0.223, rho = -0.121). Age and vitamin A levels also exhibited weak correlations: Alzheimer’s with 2DM (p-value = 0.727, rho = 0.053) and Alzheimer’s only (p-value = 0.223, rho = -0.253), neither of them was statistically significant. Symptoms of vitamin A deficiency were noted in Alzheimer's patients with T2DM, with no significant differences between groups. Dietary intake was lower for vitamin B complex, vitamin D, and multivitamins in AD patients with T2DM.
ConclusionThe findings highlight the need for further investigation into the factors influencing vitamin A metabolism in these populations. Additionally, the prevalence of vitamin A deficiency symptoms and low dietary intake of essential nutrients among patients with Alzheimer's with T2DM suggests critical areas for nutritional intervention. Addressing these deficits may improve patient outcomes and enhance overall care strategies for individuals living with Alzheimer's disease.
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The Association between the rs6656401 Locus of the CR1 Gene and Structural Alterations of Brain Effects in Han Chinese Patients with Alzheimer's Disease
More LessAuthors: Shu-Yun Zhou, Han-Xiao Lin, Jia-Ming Tang, Qing-Yu Yao, Jia-Wei Hu, Wen-Jun Long, Wen-Zhuo Dai, Tao Ma and Xi-Chen ZhuIntroductionThe complement receptor 1 (CR1) gene is identified as the one closely associated with Alzheimer's disease (AD). However, there has been no exploration of the imaging alterations associated with the CR1 gene in AD patients of the Han population. The purpose of this study is to investigate the association between the rs6656401 mutation and neuroimaging variations in Han AD patients.
MethodsWe collected nuclear magnetic resonance images from 101 patients with AD and 98 healthy controls (HC). The subjects in this study, based on the different genotypes of rs6656401, were divided into three groups, with the number of AA, AG, and GG genotypes in the AD group being 1, 17, and 83, and 1, 8, and 89 in the HC group. Data were analyzed using the dominant model. Structural differences in the brain tissue between genotypes at the rs6656401 polymorphic locus were compared using voxel-based morphological analysis, cortical thickness, and graph-theoretic analysis to construct structural networks.
ResultsSeven regions (namely, right precuneus, right caudal middle frontal cortical, right rostral middle frontal, right superior frontal, right bankssts, right superior parietal, and right paracentral) were significantly different across CR1 rs6656401 genotypes. The voxel-based morphometry analysis revealed that voxel cluster sizes in the left cerebellum, left superior temporal gyrus, right superior frontal gyrus orbital, right precuneus, and right superior parietal were significantly different in the AA, AG, and GG groups. The degree centrality (Dc) of the left inferior frontal gyrus was significantly greater in the GG group than in the AG group after false discovery rate correction in the structural network analysis.
DiscussionThis study demonstrates that the rs6656401 AA genotype primarily induces structural alterations in the frontal, temporal, and parietal lobes of AD patients, with significant changes in the right middle frontal gyrus, precuneus, and superior parietal gyrus, along with Dc index alterations in the left inferior frontal gyrus affecting brain network function. Our findings confirm the association between the rs6656401 polymorphism and AD-related brain structural changes, providing the first evidence of these regional alterations in Han Chinese AD cohorts. Future studies will elucidate the locus's pathological mechanism to inform early diagnosis and targeted therapies.
ConclusionOur study first indicated that CR1 rs6656401 genotypes significantly influenced the morphological and structural covariate networks in Han AD patients.
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Volumes & issues
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Volume 22 (2025)
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Volume 21 (2024)
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Volume 20 (2023)
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Volume 19 (2022)
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Volume 18 (2021)
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Volume 17 (2020)
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Volume 16 (2019)
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Volume 15 (2018)
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Volume 14 (2017)
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Volume 13 (2016)
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Volume 12 (2015)
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Volume 11 (2014)
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Volume 10 (2013)
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Volume 9 (2012)
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Volume 8 (2011)
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Volume 7 (2010)
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Volume 6 (2009)
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Volume 5 (2008)
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Volume 4 (2007)
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Volume 3 (2006)
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Volume 2 (2005)
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Volume 1 (2004)
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Cognitive Reserve in Aging
Authors: A. M. Tucker and Y. Stern
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