Search Results (575)

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by memory loss and cognitive decline. Its main pathological features are extracellular plaques composed of aggregated amyloid-β (Aβ) peptides and intracellular neurofibrillary tangles formed by hyperphosphorylated tau. The Aβ hypothesis proposes that Aβ accumulation is a key driver of AD, influencing tau pathology, neuroinflammation, and neurodegeneration. However, therapies that reduce Aβ have shown limited clinical benefits. This suggests that the mechanisms underlying peptide-mediated modulation of AD pathology are much more complex. Both Aβ and tau undergo various post-translational modifications (PTMs) that affect their structure, aggregation, and toxicity. In addition, these abnormal proteins are not efficiently cleared in AD, indicating dysfunction of the protein quality control (PQC) system that maintains proteostasis. Such abnormal PTMs and impaired PQC likely work together to drive disease progression, which may explain the limited success of Aβ-reduction therapies. In this review, we describe how major PTMs, including phosphorylation, ubiquitination, acetylation, glycosylation, and oxidation, regulate the pathological behavior of Aβ and tau. We also discuss the role of the PQC systems in the pathology of AD. We propose that dysregulation of PTMs and PQC constitutes a convergent mechanism underlying AD pathogenesis. Therapeutic strategies targeting these processes may provide more effective and sustained disease modification than approaches focused solely on Aβ reduction. Full article

Alzheimer’s disease (AD) is a neurodegenerative disease impacting over 6 million Americans, with cases projected to increase to over 14 million by 2060. The AD pathology leads to difficulty completing everyday tasks or conversations, and ultimately, progresses to disrupt the most basic bodily functions and require full-time caretaking. While disease-modifying therapy remains elusive, reducing the incidence of AD is crucial to mitigate the projected increase in cases. Exercise has emerged as an effective strategy to promote brain health in late adulthood and to protect against the onset of AD. Exercise opposes several disease processes, including cognitive dysfunction, amyloid beta aggregation, tau phosphorylation, and deficits in hippocampal volume, mitochondrial function, cerebral blood flow, and neurogenesis, through various pathways, including the systemic release of exerkines. The exerkine irisin is an important mediator of the beneficial relationship between exercise and the brain. Previous work administering irisin therapeutically to healthy and preclinical AD mice has demonstrated irisin use to replicate multiple exercise-induced effects in the brain and protect against AD-induced deficits. Although irisin is suggested as a promising strategy for promoting brain health in late adulthood, our understanding of irisin signaling and its protective effects against AD remains incomplete. This review will investigate irisin as an important, physiologically relevant promoter of brain health in aging and AD. Full article

Neurovascular coupling (NVC) maintains appropriate cerebral blood flow (CBF) in response to neuronal activity, and its disturbance, known as neurovascular uncoupling (NVU), is increasingly recognised as a major contributor to neurodegenerative disease. Alzheimer’s disease (AD) NVU is caused by Aβ buildup, tau pathology, endothelial dysfunction, and persistent neuroinflammation, leading to poor CBF control and blood–brain barrier (BBB) disintegration. Parkinson’s disease (PD) is characterised by α-synuclein aggregation, oxidative stress, mitochondrial dysfunction, and dopaminergic neuronal loss, all of which impede cerebrovascular regulation. These disease-specific mechanisms interact via similar vascular pathways, establishing NVU as a critical connection between neuronal degeneration and cerebrovascular dysfunction. This study highlights the critical role of NVU in neurodegeneration by investigating shared and disease-specific processes in AD and PD. Tau pathology disturbs vascular regulation in AD, whereas dopaminergic neuron loss impairs cerebrovascular control in PD. Both Aβ and α-synuclein are linked to endothelial dysfunction and oxidative stress, albeit originating in different pathologies. Comparative analysis reveals distinct vascular abnormalities in each condition, as well as shared processes such as inflammation and BBB disruption. The study also covers developments in biomarker discovery and neuroimaging techniques that allow for exact characterisation of NVU, facilitating early diagnosis and treatments. In addition, lifestyle changes and pharmacological treatments for oxidative stress and endothelial injury are being examined. This study highlights the significance of NVU as a fundamental pathogenic mechanism, underscoring its importance for comprehending disease development and formulating novel therapeutic strategies. Full article

Alzheimer’s disease (AD) develops as a progressive dementia condition through the step-by-step breakdown of nerve cells. Neurodegeneration in this context primarily results from metal ions, including copper, iron, zinc, and aluminum, building up in the system. The aggregation of amyloid-beta (Aβ) peptides and oxidative stress generation stem from metal ion involvement acting as defining characteristics of Alzheimer’s disease pathology. We developed a comprehensive mathematical model based on 24 coupled ordinary differential equations (ODEs) to represent the interactions between metal ions, Aβ peptides, reactive oxygen species (ROS), antioxidant defenses, and tau protein phosphorylation. The mathematical model monitors how metal ion concentrations change over time and examines their competitive binding effects, which trigger a series of reactions, resulting in oxidative stress and subsequent tau protein damage. The model uses analytical and numerical mathematical methods to expose nonlinear behaviors and threshold effects while offering mechanistic insights into the course of disease development. This model functions as a quantitative framework for assessing how therapeutic interventions that target metal dyshomeostasis and oxidative stress can potentially affect outcomes. Full article

Mitochondria are essential organelles that perform irreplaceable functions in neurons. The degeneration of neurons in Alzheimer’s disease (AD) is associated with mitochondrial damage, and Tau pathology represents a significant pathogenic factor in AD. However, the relationship between Tau and mitochondrial dysfunction during neuronal degeneration remains unclear. In this study, we investigated the effects and mechanisms by which extracellular Tau aggregates induce neuronal mitochondrial damage and dysfunction. The results showed that extracellular Tau aggregates lead to structural damage of mitochondria in SH-SY5Y cells and disrupt mitochondrial homeostasis. Extracellular Tau aggregates can also cause mitochondrial oxidative stress and inhibit oxidative phosphorylation in SH-SY5Y cells. Concurrently, extracellular Tau aggregates promote neuronal death through an increase in cytochrome C, mtDNA leakage and activation of the cGAS/STING pathway. We also explored the effects of a single-chain variable fragment antibody (scFv T1) and found that scFv T1 alleviated mitochondrial damage and dysfunction by inhibiting the formation of Tau aggregates. These findings suggest that targeting Tau pathology may be crucial to address neuronal mitochondrial impairment and that reduction of the toxicity associated with extracellular Tau aggregates could help slow Tau pathology progression. Full article

Alzheimer’s disease (AD) is the most prevalent form of dementia and is characterized by abnormal aggregation of β-amyloid (Aβ) peptides, tau proteins, and neuroinflammation in the central nervous system (CNS). While most AD research has focused on the brain, the molecular pathology of the spinal cord remains poorly understood. In this study, we investigated amyloid pathology, neurodegeneration, neuroinflammation, and cholesterol metabolism across distinct regions of the spinal cord and examined sex-specific differences using a model of AD, 5xFAD mice. Our data reveal that Aβ accumulation was restricted to the cervical spinal cord at 3 months but was evident in all areas of the spinal cord by 9 months, with similar patterns in both female and male animals. Despite this early and progressive Aβ deposition, no significant neuronal loss was observed in the ventral horn of the cervical spinal cord in either sex at 3 or 9 months of age. In contrast, there was a significant positive correlation between Aβ deposition and Iba1+ cell density in the spinal cord of 5xFAD mice. The number of Iba1+ cells in both the grey and white matter was significantly increased in female and male 5xFAD mice compared with age-matched wild-type (WT) littermates at 9 months of age. Astrocytic responses, however, were sex-specific: female, but not male, 5xFAD mice exhibited a significant increase in GFAP+ astrocytes in the grey matter of the thoracic and lumber spinal cord at 9 months compared with 3 months and relative to age-matched WT controls in the cervical and thoracic spinal cord. Furthermore, GFAP+ area in the thoracic spinal cord was significantly higher in female 9-month-old 5xFAD mice compared with their male counterparts, indicating a female-specific astrocytic response in AD spinal cord pathology. Our data also show an increase in free cholesterol (Filipin+ area) in 5xFAD mice at 9 months relative to WT controls, accompanied by altered expression of cholesterol metabolism genes, including downregulation of Abca1, Cyp46a1 and Cyp27a1. Collectively, these findings provide new insights into AD progression in the spinal cord, highlighting molecular pathology of AD extending beyond the brain. Full article

Alzheimer’s disease (AD) is the leading cause of dementia, responsible for approximately 60–70% of cases globally. AD is a gradually progressive neurodegenerative disorder that is characterized by widespread deposition of β-amyloid (Aβ) plaques, followed by aggregation of tau protein in the neocortex, neurodegeneration, and cognitive decline. Within these complex pathological interactions, Aβ and tau proteins, together with astrogliosis, neuroinflammation, and other factors, play a key role in the development of clinical AD. Accumulating evidence indicates that the formation of protein oligomers, followed by their aggregation into pathological fibrils, constitutes an early and critical step in the pathogenesis of the disease. Specific pathological proteins are often treated as biomarkers of particular diseases because their presence, concentration, or altered structure reflects an underlying disease process. It is well established that the Aβ and tau proteins are the key hallmarks of AD, and their mutual interaction may significantly influence the pathology of the disease. Early diagnosis is crucial for maximizing the therapeutic benefits of currently available symptomatic treatments, which can alleviate symptoms and modestly delay clinical deterioration in patients with AD. This review highlights the mechanisms involved in protein-dependent neurodegeneration and describes both traditional and novel approaches for the cure of AD. The most important aspect of this publication is the integration of the two key proteins: Aβ and tau, and the resulting shift toward a new therapeutic approach. Full article

DP-128 is a multitarget benzonaphthyridine-6-chlorotacrine hybrid molecule with potent in vitro anticholinesterase and Aβ42 and tau anti-aggregating activity. While often used as a reference protein aggregation inhibitor, its further development as an anti-Alzheimer agent is limited by significant cytotoxicity, suboptimal aqueous solubility and microsomal stability. Since these drawbacks might arise from its rather high lipophilicity, in this work we have developed a series of more polar analogues, designed by structural modifications at the benzonaphthyridine or 6-chlorotacrine moieties or within the eight-atom linker. Half of the new analogues are indeed slightly more soluble and clearly less cytotoxic than DP-128, display single-digit acetylcholinesterase inhibitory activity, and retain the Aβ42 and tau anti-aggregating potency of the lead, as well as favourable brain permeation and high plasma stability. While further optimization of microsomal stability is necessary for a potential therapeutic use of this class of compounds, hybrids 16 and 17, with similar or even higher Aβ42 and tau anti-aggregating activity and lower cytotoxicity than DP-128, might represent novel pharmacological tools for protein aggregation studies. Full article

The increasing prevalence of obesity and Alzheimer’s disease (AD) in the aging population underscores an urgent need to understand the common cellular and metabolic mechanisms they share. Accumulated evidence suggests that overlapping metabolic disturbances contribute to the pathogenesis of these two conditions. In this review, we highlight key underlying interconnecting metabolic pathways: (1) adipose-brain crosstalk mediated by adipokines and adipose tissue-derived extracellular vesicles that can modulate neuronal function and amyloid pathology, (2) dysregulated lipid metabolism affecting cholesterol, sphingolipids, and phospholipids and thereby promoting inflammation, amyloid precursor protein processing, and tau hyperphosphorylation, (3) impaired glycolysis and insulin resistance, which accelerate both obesity and neurodegenerative processes, (4) mitochondrial dysfunction marked by disrupted tricarboxylic acid cycle enzymes and electron transport chain complexes, leading to elevated reactive oxygen species and driving both obesity and AD pathology, and (5) gut microbiota dysbiosis, which can trigger inflammation as well as amyloid and tau aggregation. Together, these mechanisms show that metabolic alterations appear early, preceding clinical disease, and that understanding these underlying connections can provide strategies to protect metabolic health and prevent disease progression. Full article

Neurodegenerative diseases arise when normally functional aggregation-prone proteins transition into stable cross-β amyloid fibrils. Although these fibrils share a conserved architecture, the pathways that lead to fibrillation vary across proteins and cellular environments. Liquid–liquid phase separation is now recognized as a central organizer of intracellular biochemistry that modulates protein aggregation. Physiological condensation can buffer aggregation by maintaining macromolecular solubility and providing partner interactions that compete against pathological protein–protein interactions. However, condensates can transform and age into gel-like states that can favor the emergence of β-rich oligomers and solid-state fibrils. Across six disease-linked proteins that include Tau, α-synuclein, amyloid-β, TDP-43, FUS, and hnRNPA1, we compare how sequence-encoded interaction motifs, cellular cofactors, and interfacial microenvironments shape the balance between physiological condensates and pathological amyloids. Here, we highlight the unifying drivers of aggregation and intervention points that preserve native function while limiting toxic amyloid formation. Full article

Background: Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterized by amyloid-β aggregation, tau hyperphosphorylation, oxidative stress, and mitochondrial dysfunction. Emerging evidence indicates that the gut microbiota plays a critical role in modulating neuroinflammatory, and metabolic pathways involved in AD pathogenesis through the microbiota-gut-brain axis. Objective: This systematic review aims to comprehensively evaluate the role of the microbiota-gut-brain axis in Alzheimer’s disease, with a particular focus on its mechanistic links to oxidative stress, mitochondrial dysfunction, and amyloid pathology, as well as its therapeutic potential. Methodology: A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science databases, focusing on studies evaluating gut microbiota composition, metabolomic changes, oxidative stress markers, mitochondrial activity, and therapeutic interventions in AD models and patients. Results: Altered gut microbial composition in AD is associated with increased pro-inflammatory taxa (Escherichia-Shigella, Bacteroides) and depletion of short-chain fatty acid (SCFA) producing bacteria (Faecalibacterium, Roseburia). Dysbiosis contributes to systemic inflammation, disrupted intestinal permeability, and microglial activation, leading to oxidative damage and mitochondrial impairment in neurons. Preclinical and clinical studies indicate that probiotics, prebiotics, and fecal microbiota transplantation can restore redox balance, reduce neuroinflammation, and improve cognitive outcomes. Multi-omics and AI-based models are emerging as tools for identifying microbiome-derived biomarkers for early AD detection. Conclusion: The gut microbiota-mitochondria-oxidative stress axis represents a promising therapeutic target in Alzheimer’s disease. Future research should focus on longitudinal human studies, standardized microbial profiling, and personalized microbiome-based interventions to translate these mechanistic insights into clinical benefit. Full article

Alzheimer’s disease (AD) is a neurodegenerative disorder first described more than one century ago. Over this time, many features of the disease have been discovered and, consequently, many different approaches in the diagnosis and treatment of AD have been developed. A major assumption has guided research on AD in the past: this fatal form of cognitive decline is believed to have a pathogenic basis in the deposition of amyloid beta (Aβ) aggregates throughout the brain. Consequently, a main goal of AD therapy is to reduce Aβ load, and several monoclonal antibodies targeting amyloid are among the most recent approaches to AD treatment. However, the effectiveness of these drugs is limited, as they cannot block the progression of the disease; they only slow it down in certain conditions. Many other causative factors are known to promote the development of the disease, with immune system involvement being the most investigated. Indeed, it has been well documented that the microglial response enhances the deposition of other altered proteins, such as Tau, and induces a neurotoxic microenvironment that promotes neuronal loss. In this scenario, the interaction between microglia and astrocytes is known to accelerate pathogenic processes, and a possible role for peripheral T lymphocytes in AD pathology has also been described. An interesting hypothesis is that immune cells driving chronic inflammation might worsen AD progression and, therefore, could represent a target for treatment strategies in this disease. Thus, this review article aims to summarise the role of brain and peripheral immune molecules and cells in AD. Also, immune-based treatments for AD are described, including those targeting microglia and T cells. Full article

Diabetes Mellitus is a chronic metabolic disorder characterized by impaired insulin production and/or action, leading to persistent hyperglycemia and insulin resistance. It has been associated with several comorbidities, including cognitive dysfunction, affecting functions such as attention, memory, and processing speed. Mounting evidence indicates a complex relationship between type 2 Diabetes Mellitus (DM2) and neurodegenerative disorders such as mild cognitive impairment and Alzheimer’s disease (AD). Beyond the conventional hallmarks of each pathology, patients with DM2 face an increased risk of neuronal degeneration, while AD is characterized by a marked reduction in insulin receptor density. Although aging, neuroinflammation, and vascular dysfunction have been recognized as key risk factors in AD, the precise molecular mechanisms driving AD pathogenesis remain incompletely understood. Various studies have been conducted to identify reliable biomarkers that elucidate the connection between DM2 and AD, including insulin dysregulation, neuroinflammation, amyloid-β aggregation, and tau hyperphosphorylation. Investigation of these biomarkers is still ongoing, and they may serve not only as diagnostic tools but also as therapeutic targets. Here, we review the current evidence supporting a convergent biological framework between DM2 and AD. Clarifying these shared pathways may improve early detection and guide the development of targeted therapeutic strategies aimed at reducing neurodegeneration in metabolically vulnerable populations. Full article

Alzheimer’s (AD) and Parkinson’s disease (PD) are prominent neurodegenerative disorders characterized by early synaptic loss, which correlates more closely with clinical symptoms than neuronal death. This synaptic impairment is primarily driven by disruptions in synaptic vesicle (SV) trafficking, a critical process for maintaining synaptic integrity through a tightly regulated cycle involving clustering, docking-priming, Ca²⁺-triggered fusion, and endocytosis. In AD, amyloid-β (Aβ) oligomers interfere with SNARE-mediated fusion and endocytosis, while hyperphosphorylated tau obstructs vesicle mobility and docking, resulting in cumulative toxicity that aggravates SV defects. Conversely, in PD, α-synuclein (α-syn) aggregation alters vesicle clustering, membrane fusion, and recycling, and these effects are further influenced by Leucine-rich repeat kinase 2 (LRRK2)-Rab-related trafficking defects and the selective vulnerability of dopaminergic terminals. Different from previous reviews that address synaptic dysfunction in a broader manner, the present review is specifically organized around the SV trafficking cycle and compares both shared presynaptic endpoints and disease-specific upstream mechanisms in AD and PD. In addition, recent mechanism-oriented therapeutic strategies are summarized. This vesicle-cycle-centered perspective may provide a clearer framework for understanding presynaptic pathology and for guiding the development of earlier and more targeted interventions. Full article

Introduction: Olives have been used in traditional Mediterranean medicine for thousands of years to address the causes of inflammation, ageing and cognitive health. Traditional preparations of olive include olive oil and olive leaf extract, which are major components of diets that contribute to maintaining cognitive function and reducing neurodegenerative disease risk. Aims of the study: This systematic review aimed to synthesise experimental and limited human evidence on olive biophenols in neurodegenerative disease models, identify the most studied compounds, characterise their mechanisms of action, and evaluate key translational barriers. Materials and methods: Following PRISMA 2020 guidelines and registered with PROSPERO (CRD420251252252), primary studies investigating the effects of well-characterised olive biophenols in neurodegenerative relevant in vitro, in vivo, or human models were systematically reviewed. Each study was assessed for its design, experimental model, mechanistic outcomes and reported limitations. Risk of bias was evaluated using validated tools (SYRCLE/OHAT/ToxR) appropriate for preclinical and experimental study designs. Results: Among the 25 studies, 7 (28.0%) examined oleuropein or oleuropein aglycone, 10 (40.0%) focused on hydroxytyrosol or its derivatives, and 9 (36.0%) investigated oleocanthal. Most studies employed in vivo animal models (57.7%), predominantly transgenic mouse models of AD and toxin-induced PD models. Oleuropein-based studies reported inhibition of amyloid-β and α-synuclein aggregation with behavioural improvements. Hydroxytyrosol primarily exerted antioxidant and anti-inflammatory effects with modest cognitive benefits. Oleocanthal showed the most consistent anti-amyloid and anti-tau activity, including enhanced amyloid-β clearance across the blood–brain barrier. Most studies show a moderate risk of bias due to incomplete reporting, randomisation and blinding. Conclusions: Olive biophenols demonstrate consistent neuroprotective effects in preclinical models; however, translation to clinical application remains limited by pharmacokinetic constraints, methodological heterogeneity, and insufficient human evidence. Full article