The physiological roles of tau and Aβ: implications for Alzheimer's disease pathology and therapeutics

Neuronal plasticity and its role in Alzheimer's disease and Parkinson's disease

Neuronal plasticity, the brain's ability to adapt structurally and functionally, is essential for learning, memory, and recovery from injuries. In neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, this plasticity is disrupted, leading to cognitive and motor deficits. This review explores the mechanisms of neuronal plasticity and its effect on Alzheimer's disease and Parkinson's disease. Alzheimer's disease features amyloid-beta plaques and tau tangles that impair synaptic function, while Parkinson's disease involves the loss of dopaminergic neurons affecting motor control. Enhancing neuronal plasticity offers therapeutic potential for these diseases. A systematic literature review was conducted using databases such as PubMed, Scopus, and Google Scholar, focusing on studies of neuronal plasticity in Alzheimer's disease and Parkinson's disease. Data synthesis identified key themes such as synaptic mechanisms, neurogenesis, and therapeutic strategies, linking molecular insights to clinical applications. Results highlight that targeting synaptic plasticity mechanisms, such as long-term potentiation and long-term depression, shows promise. Neurotrophic factors, advanced imaging techniques, and molecular tools (e.g., clustered regularly interspaced short palindromic repeats and optogenetics) are crucial in understanding and enhancing plasticity. Current therapies, including dopamine replacement, deep brain stimulation, and lifestyle interventions, demonstrate the potential to alleviate symptoms and improve outcomes. In conclusion, enhancing neuronal plasticity through targeted therapies holds significant promise for treating neurodegenerative diseases. Future research should integrate multidisciplinary approaches to fully harness the therapeutic potential of neuronal plasticity in Alzheimer's disease and Parkinson's disease.

Inflammasome links traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease

Traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease are three distinct neurological disorders that share common pathophysiological mechanisms involving neuroinflammation. One sequela of neuroinflammation includes the pathologic hyperphosphorylation of tau protein, an endogenous microtubule-associated protein that protects the integrity of neuronal cytoskeletons. Tau hyperphosphorylation results in protein misfolding and subsequent accumulation of tau tangles forming neurotoxic aggregates. These misfolded proteins are characteristic of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease and can lead to downstream neuroinflammatory processes, including assembly and activation of the inflammasome complex. Inflammasomes refer to a family of multimeric protein units that, upon activation, release a cascade of signaling molecules resulting in caspase-induced cell death and inflammation mediated by the release of interleukin-1β cytokine. One specific inflammasome, the NOD-like receptor protein 3, has been proposed to be a key regulator of tau phosphorylation where it has been shown that prolonged NOD-like receptor protein 3 activation acts as a causal factor in pathological tau accumulation and spreading. This review begins by describing the epidemiology and pathophysiology of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease. Next, we highlight neuroinflammation as an overriding theme and discuss the role of the NOD-like receptor protein 3 inflammasome in the formation of tau deposits and how such tauopathic entities spread throughout the brain. We then propose a novel framework linking traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease as inflammasome-dependent pathologies that exist along a temporal continuum. Finally, we discuss potential therapeutic targets that may intercept this pathway and ultimately minimize long-term neurological decline.

The role of mitochondrial dysfunction in the pathogenesis of Alzheimer's disease and future strategies for targeted therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline, behavioral impairments, and psychiatric comorbidities. The pathogenesis of AD remains incompletely elucidated, despite advances in dominant hypotheses such as the β-amyloid (Aβ) cascade, tauopathy, cholinergic deficiency, and neuroinflammation mechanisms. However, these hypotheses inadequately explain the multifactorial nature of AD, which exposes limitations in our understanding of its mechanisms. Mitochondrial dysfunction is known to play a pivotal role in AD, and since patients exhibit intracellular mitochondrial dysfunction and structural changes in the brain at an early stage, correcting the imbalance of mitochondrial homeostasis and the cytopathological changes caused by it may be a potential target for early treatment of AD. Mitochondrial structural abnormalities accelerate AD pathogenesis. For instance, structural and functional alterations in the mitochondria-associated endoplasmic reticulum membrane (MAM) can disrupt intracellular Ca2⁺ homeostasis and cholesterol metabolism, consequently promoting Aβ accumulation. In addition, the overaccumulation of Aβ and hyperphosphorylated tau proteins can further damage neurons by disrupting mitochondrial integrity and mitophagy, thereby amplifying pathological aggregation and exacerbating neurodegeneration in AD. Furthermore, Aβ deposition and abnormal tau proteins can disrupt mitochondrial dynamics through dysregulation of fission/fusion proteins, leading to excessive mitochondrial fragmentation and subsequent dysfunction. Additionally, hyperphosphorylated tau proteins can impair mitochondrial transport, resulting in axonal dysfunction in AD. This article reviews the biological significance of mitochondrial structural morphology, dynamics, and mitochondrial DNA (mtDNA) instability in AD pathology, emphasizing mitophagy abnormalities as a critical contributor to AD progression. Additionally, mitochondrial biogenesis and proteostasis are critical for maintaining mitochondrial function and integrity. Impairments in these processes have been implicated in the progression of AD, further highlighting the multifaceted role of mitochondrial dysfunction in neurodegeneration. It further discusses the therapeutic potential of mitochondria-targeted strategies for AD drug development.

Acute targeting of N-terminal tau protein has long-lasting beneficial effects in Tg2576 APP/Aβ mouse model by reducing cognitive impairment, cerebral Aβ-amyloidosis, synaptic remodeling and microgliosis later in life

Even though the number of patients suffering from Alzheimer's Disease (AD) is rapidly growing worldwide, only a few symptomatic treatments have been approved for clinical use, pointing out the urgent need for more effective disease-modifying therapies that actually alter the progression of this neurodegenerative disorder which is characterized by co-occurence of both Amyloid beta (Aβ) and tau neuropathologies. Preclinical and clinical evidence suggests that a link between Aβ and tau drives the entire continuum of AD pathobiology. 12A12 is a monoclonal antibody (mAb) which offers neuroprotection into two transgenic lines of AD, including Tg2576 that overexpresses Swedish mutation (KM670/671NL) of Amyloid Precursor Protein (APP, isoform 695) and 3xTg (APP Swedish, MAPT P301L, and PSEN1 M146V), by targeting the 20-22kDa N-terminal tau fragments (NH2htau). In particular, acute (over 14 days with 4 doses), intravenous injection of 12A12mAb leads to significant improvement of cognitive, biochemical and histopathological AD signs in symptomatic 6-month-old Tg2576, a well-established transgenic mouse model that mimics the human amyloidosis with an age-dependent Aβ accumulation/aggregation and plaque deposition. Here, we report that Tg2576 mice, immunized with 12A12mAb at 6 months of age and returned to their home cage for additional 3 months, exhibit preserved spatial memory despite the anticipated interruption of antibody administration (discontinuous treatment). This enduring beneficial effect on memory deficit (up to 90 days after the last injection) is accompanied by normalization in the synaptic imbalance and microgliosis along with decrease of the most toxic A11-positive prefibrillar oligomers and inverse increase in 4kDa monomeric form(s) of Aβ 1-42. These findings reveal that: (i) soluble, pathogenetic tau specie(s) located at the N-terminal domain of protein early synergizes with Aβ in driving the progression of AD neuropathology; (ii) transient immunoneutralization of the NH2htau following short-term treatment with 12A12mAb exerts preventive, long-lasting neuroprotective effects, at least in part by interfering at "pre-plaque" stage with the progressive deposition of insoluble, fibrillar Aβ via a shift of its aggregation pathway into its less harmful, unaggregated monomeric forms. Taken together, these findings represent a strong rationale for the advancement of 12A12mAb to clinical stage aiming at preventing the Aβ-dependent neurodegeneration by lowering the cerebral levels of NH2htau in humans suffering from chronic, slow-progressing AD.

Mapping the hippocampal spatial proteomic signature in male and female mice of an early Alzheimer's disease model

BACKGROUND

Hippocampal dysfunction induced by soluble amyloid-β oligomers (oAβ) is an early neuropathological hallmark of Alzheimer's disease (AD). oAβ shifts hippocampal synaptic-plasticity induction threshold facilitating long-term depression (LTD) instead of long-term potentiation (LTP, the functional basis of memory), thereby leading to memory deficits in early AD-like amyloidosis mouse models. In this regard, the spatial distribution of the underlying synaptic-plasticity/memory proteome changes in the hippocampus, and potential sex differences, remain unknown. Here we postulated that some protein changes related to synaptic-plasticity and memory may be unique to sex and/or specific to the dorsal or ventral hippocampus -as both regions have distinct functionality and connectivity-, potentially providing sex- and spatial-specific proteomic phenotypes for early AD-amyloidosis interventions.

METHODS

An innovative spatial-resolution proteomics study was performed to map whole hippocampal proteome distribution using matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry. For this purpose, sixteen adult male and female mouse brains intracerebroventricularly injected with oAβ1-42/vehicle were analyzed. MALDI-imaging RapifleXTM-MALDI-TissuetyperTM TOF/TOF mass spectrometer was used, followed by traditional tandem mass spectrometry (MS/MS) for precise protein identification on tissue.

RESULTS

34 proteins showed significant differences in expression levels due to treatment, sex, or hippocampal location among 234 peptides initially detected; and displayed significant protein-protein interaction (PPI), indicating main functional relationship to LTP/LTD pathways and memory. Thus, 14 proteins related to synaptic-plasticity and/or AD were further studied, showing that most modulated glycogen synthase kinase-3β (GSK-3β), a protein widely involved in synaptic-plasticity induction threshold regulation towards LTD. Accordingly, hippocampal GSK-3β was found to be overactivated in AD-like amyloidosis mice.

CONCLUSIONS

We show for the first-time specific sex-dependent synaptic-plasticity proteome changes in dorsal/ventral hippocampi that modulate GSK-3β activity. These findings provide new insight into the early amyloidosis pathogenesis in AD and offer valuable, unique proteomic phenotypes as potential biomarkers and targets for early diagnosis and therapy in both sexes.

Navigating the complexities of neuronal signaling and targets in neurological disorders: From pathology to therapeutics

Neurological disorders arising from structural and functional disruptions in the nervous system present major global health challenges. This review examines the intricacies of various cellular signaling pathways, including Nrf2/Keap1/HO-1, SIRT-1, JAK/STAT3/mTOR, and BACE-1/gamma-secretase/MAPT, which play pivotal roles in neuronal health and pathology. The Nrf2-Keap1 pathway, a key antioxidant response mechanism, mitigates oxidative stress, while SIRT-1 contributes to mitochondrial integrity and inflammation control. Dysregulation of these pathways has been identified in neurodegenerative and neuropsychiatric disorders, including Alzheimer's and Parkinson's diseases, characterized by inflammation, protein aggregation, and mitochondrial dysfunction. Additionally, the JAK/STAT3 signaling pathway emphasizes the connection between cytokine responses and neuroinflammation, further compounding disease progression. This review explores the crosstalk among these signaling networks, elucidating how their disruption leads to neuronal decline. It also addresses the dual roles of these pathways, presenting challenges in targeting them for therapeutic purposes. Despite the potential benefits of activating neuroprotective pathways, excessive stimulation may cause deleterious effects, including tumorigenesis. Future research should focus on designing multi-targeted therapies that enhance the effectiveness and safety of treatments, considering individual variabilities and the obstacles posed by the blood-brain barrier to drug delivery. Understanding these complex signaling interactions is crucial for developing innovative and effective neuroprotective strategies that could significantly improve the management of neurological disorders.

Advancements in Stem Cell Research for Effective Therapies Against Alzheimer's Disease: Current Investigation and Future Insight

Alzheimer's disease (AD) is the most prevalent cause of dementia in the elderly, affecting approximately 50 million individuals globally with significant impose in health and financial burdens. Despite extensive research, no current treatment effectively halts the progression of AD, primarily due to its complex pathophysiology of the disease and the limitations of available therapeutic approaches. In this context, stem cell transplantation has emerged as a promising treatment strategy, harnessing the regenerative capabilities of various stem cell types, including neural stem cells (NSCs), embryonic stem cells (ESCs), and mesenchymal stem cells (MSCs). This review explores the potential of stem cell-based therapies in AD, emphasizing the necessity for continued innovation to overcome existing challenges and enhance therapeutic efficacy. Briefly, NSCs have shown potential in improving cognitive function and reducing AD pathology through targeted transplantation and neuroprotection; however, challenges such as optimizing transplantation protocols and ensuring effective cell integration persist. Concurrently, ESCs, with their pluripotent nature, present opportunities for modulating AD and generating therapeutic neurons, but ethical concerns and immunogenicity present significant obstacles to clinical application. Moreover, MSCs have demonstrated potential in ameliorating AD-related pathology and promoting neurogenesis, offering a more accessible alternative with fewer ethical constraints. The review concludes that the combinatory approaches of different stem cells may provide synergistic benefits in addressing AD-related pathophysiology, warranting further exploration in future research.

West Nile virus non-structural protein 1 promotes amyloid Beta deposition and neurodegeneration

Recent observations highlight a notable surge in West Nile Virus (WNV) infections in Europe that can lead to neuroinvasive consequences associated with neurodegeneration, mainly triggered by WNV Non-Structural protein 1 (NS1). During viral replication, various protein-protein interactions take place, allowing viral proteins to interact with host factors. NS1 is actively secreted in the bloodstream by infected cells and is known to affect endothelial permeability and host immune response. Focusing on the recently discovered antimicrobial roles of Amyloid-Beta (Aβ) in the context Central Nervous System (CNS), we connected WNV late pathology to overlapping features encountered in neurodegenerative diseases. In fact, CNS viral infections, or presence of specific viral components, activate glial cells, which in turn increase Aβ expression as an antiviral mechanism, leading to Aβ accumulation and neuronal damage. Considering West Nile neuroinvasive disease (WNND) as a possible complication of WNV infection, we investigated the impact of soluble WNV (s)NS1 on glial and neuronal cells, in 2D and 3D in vitro models. We reported an increased Aβ deposition after WNV sNS1 treatment, particularly of Aβ-142 isoform, and increased glial activation with a subsequent neurotoxicity. These findings underscore the crucial role of sNS1 in CNS-related effects during WNV infection, suggesting a novel pathogenetic role.

Synergistic effects of the Aβ/fibrinogen complex on synaptotoxicity, neuroinflammation, and blood-brain barrier damage in Alzheimer's disease models

INTRODUCTION

Alzheimer's disease (AD) is characterized by amyloid-beta (Aβ), hyperphosphorylated tau, chronic neuroinflammation, blood-brain barrier (BBB) damage, and synaptic dysfunction, leading to neuronal loss and cognitive deficits. Vascular proteins, including fibrinogen, extravasate into the brain, further contributing to damage and inflammation. Fibrinogen's interaction with Aβ is well-established, but how this interaction contributes to synaptic dysfunction in AD is unknown.

METHODS

Organotypic hippocampal cultures (OHC) were exposed to Aβ42 oligomers, fibrinogen, or Aβ42/fibrinogen complexes. Synaptotoxicity was analyzed by Western blot. Aβ42 oligomers, fibrinogen, or their complexes were intracerebroventricularly injected into mice. Histopathological AD markers, synaptotoxicity, neuroinflammation, and vascular markers were observed by Western blot and immunofluorescence.

RESULTS

Aβ42/fibrinogen complexes led to synaptic loss, tau181 phosphorylation, neuroinflammation, and BBB disruption, independent of Mac1/CD11b receptor signaling. Blocking Aβ42/fibrinogen complex formation prevented synaptotoxicity.

DISCUSSION

These findings indicate that the Aβ42/fibrinogen complex has a synergistic impact on hippocampal synaptotoxicity and neuroinflammation.

HIGHLIGHTS

Fibrinogen binds to the central region of Aβ, forming a plasmin-resistant complex. The Aβ/fibrinogen complex induces synaptotoxicity, inflammation, and BBB disruption. Synaptotoxicity induced by the complex is independent of Mac1 receptor signaling.

Divergent actions of physiological and pathological amyloid-β on synapses in live human brain slice cultures

In Alzheimer's disease, amyloid beta (Aβ) and tau pathology are thought to drive synapse loss. However, there is limited information on how endogenous levels of tau, Aβ and other biomarkers relate to patient characteristics, or how manipulating physiological levels of Aβ impacts synapses in living adult human brain. Using live human brain slice cultures, we report that Aβ1-40 and tau release levels vary with donor age and brain region, respectively. Release of other biomarkers such as KLK-6, NCAM-1, and Neurogranin vary between brain region, while TDP-43 and NCAM-1 release is impacted by sex. Pharmacological manipulation of Aβ in either direction results in a loss of synaptophysin puncta, with increased physiological Aβ triggering potentially compensatory synaptic transcript changes. In contrast, treatment with Aβ-containing Alzheimer's disease brain extract results in post-synaptic Aβ uptake and pre-synaptic puncta loss without affecting synaptic transcripts. These data reveal distinct effects of physiological and pathological Aβ on synapses in human brain tissue.

Peripheral Inflammation and Insulin Resistance: Their Impact on Blood-Brain Barrier Integrity and Glia Activation in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory impairment, and synaptic dysfunction. The accumulation of amyloid beta (Aβ) plaques and hyperphosphorylated tau protein leads to neuronal dysfunction, neuroinflammation, and glial cell activation. Emerging evidence suggests that peripheral insulin resistance and chronic inflammation, often associated with type 2 diabetes (T2D) and obesity, promote increased proinflammatory cytokines, oxidative stress, and immune cell infiltration. These conditions further damage the blood-brain barrier (BBB) integrity and promote neurotoxicity and chronic glial cell activation. This induces neuroinflammation and impaired neuronal insulin signaling, reducing glucose metabolism and exacerbating Aβ accumulation and tau hyperphosphorylation. Indeed, epidemiological studies have linked T2D and obesity with an increased risk of developing AD, reinforcing the connection between metabolic disorders and neurodegeneration. This review explores the relationships between peripheral insulin resistance, inflammation, and BBB dysfunction, highlighting their role in glial activation and the exacerbation of AD pathology.

Unraveling the Complexity of Alzheimer's Disease: Insights into Etiology and Advancements in Treatment Strategies

Alzheimer's disease, a complex and progressive neurological disorder, is the leading cause of late-life dementia. Pathologically, it is marked by the presence of amyloid plaques and neurofibrillary tangles in the brain. Over the past two decades, advancements in understanding the disease's pathogenesis have spurred research into new pharmacological treatments that target its underlying mechanisms. Currently available drugs, such as acetylcholinesterase inhibitors (rivastigmine, galantamine, donepezil) and the NMDA receptor antagonist memantine, primarily address symptoms and are effective only in the later stages of the disease. While these medications can slow disease progression and provide symptomatic relief, they do not offer a cure. Despite having a clear understanding of Alzheimer's neuropathology, the precise mechanisms driving the disease remain elusive. The lack of effective treatments that can stop the start and progression of the disease may be caused by our incomplete understanding of the pathogenic process. New therapeutic targets are now available due to the significant advancements made in pathophysiology over the past few years, which should allow for a direct attack on the underlying illness process. The various pathophysiological pathways that underlie Alzheimer's disease and how it is managed by conventional medication therapy, including current exploratory therapeutic options, are covered in this review article. Innovative, beneficial policies are essential to determine and progress therapeutic molecules to defend against AD.

Morphological and Molecular Profiling of Amyloid-β Species in Alzheimer's Pathogenesis

Alzheimer's disease (AD) is the most common form of dementia around the world (~ 65%). Here, we portray the neuropathology of AD, biomarkers, and classification of amyloid plaques (diffuse, non-cored, dense core, compact). Tau pathology and its involvement with Aβ plaques and cell death are discussed. Amyloid cascade hypotheses, aggregation mechanisms, and molecular species formed in vitro and in vivo (on- and off-pathways) are described. Aβ42/Aβ40 monomers, dimers, trimers, Aβ-derived diffusible ligands, globulomers, dodecamers, amylospheroids, amorphous aggregates, protofibrils, fibrils, and plaques are characterized (structure, size, morphology, solubility, toxicity, mechanistic steps). An update on AD-approved drugs by regulatory agencies, along with new Aβ-based therapies, is presented. Beyond prescribing Aβ plaque disruptors, cholinergic agonists, or NMDA receptor antagonists, other therapeutic strategies (RNAi, glutaminyl cyclase inhibitors, monoclonal antibodies, secretase modulators, Aβ aggregation inhibitors, and anti-amyloid vaccines) are already under clinical trials. New drug discovery approaches based on "designed multiple ligands", "hybrid molecules", or "multitarget-directed ligands" are also being put forward and may contribute to tackling this highly debilitating and fatal form of human dementia.

Inducers and modulators of protein aggregation in Alzheimer's disease - Critical tools for understanding the foundations of aggregate structures

Amyloidogenic protein aggregation is a pathological hallmark of Alzheimer's Disease (AD). As such, this critical feature of the disease has been instrumental in guiding research on the mechanistic basis of disease, diagnostic biomarkers and preventative and therapeutic treatments. Here we review identified molecular triggers and modulators of aggregation for two of the proteins associated with AD: amyloid beta and tau. We aim to provide an overview of how specific molecular factors can impact aggregation kinetics and aggregate structure to promote disease. Looking toward the future, we highlight some research areas of focus that would accelerate efforts to effectively target protein aggregation in AD.

Targeted protein degradation with bifunctional molecules as a novel therapeutic modality for Alzheimer's disease & beyond

Alzheimer's disease (AD) is associated with memory and cognitive impairment caused by progressive degeneration of neurons. The events leading to neuronal death are associated with the accumulation of aggregating proteins in neurons and glia of the affected brain regions, in particular extracellular deposition of amyloid plaques and intracellular formation of tau neurofibrillary tangles. Moreover, the accumulation of pathological tau proteoforms in the brain concurring with disease progression is a key feature of multiple neurodegenerative diseases, called tauopathies, like frontotemporal dementia (FTD) where autosomal dominant mutations in the tau encoding MAPT gene provide clear evidence of a causal role for tau dysfunction. Observations from disease models, post-mortem histology, and clinical evidence have demonstrated that pathological tau undergoes abnormal post-translational modifications, misfolding, oligomerization, changes in solubility, mislocalization, and intercellular spreading. Despite extensive research, there are few disease-modifying or preventative therapeutics for AD and none for other tauopathies. Challenges faced in tauopathy drug development include an insufficient understanding of pathogenic mechanisms of tau proteoforms, limited specificity of agents tested, and inadequate levels of brain exposure, altogether underscoring the need for innovative therapeutic modalities. In recent years, the development of experimental therapeutic modalities, such as targeted protein degradation (TPD) strategies, has shown significant and promising potential to promote the degradation of disease-causing proteins, thereby reducing accumulation and aggregation. Here, we review all modalities of TPD that have been developed to target tau in the context of AD and FTD, as well as other approaches that with innovation could be adapted for tau-specific TPD.

Dietary Flavonoid Chrysin Functions as a Dual Modulator to Attenuate Amyloid-β and Tau Pathology in the Models of Alzheimer's Disease

Growing evidence indicates that healthy diets are associated with a slower progression of Alzheimer's disease (AD). Flavonoids are among the most abundant natural products in diets beneficial to AD, such as the Mediterranean diet. However, the effect and mechanism of these dietary flavonoids on AD remains incompletely understood. Here, we found that a representative dietary natural flavonoid, chrysin (Chr), significantly ameliorated cognitive impairment and AD pathology in APP/PS1 mice. Furthermore, mechanistic studies showed that Chr significantly reduced the levels of amyloid-β (Aβ) and phosphorylated tau (p-tau), along with dual inhibitory activity against β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and glycogen synthase kinase 3β (GSK3β). Moreover, the effect of Chr was further confirmed by EW233, a structural analog of Chr that exhibited an improved pharmacokinetic profile. To further verify the role of Chr and EW233, we utilized our previously established chimeric human cerebral organoid (chCO) model for AD, in which astrogenesis was promoted to mimic the neuron-astrocyte ratio in human brain tissue, and similar dual inhibition of Aβ and p-tau was also observed. Altogether, our study not only reveals the molecular mechanisms through which dietary flavonoids, such as Chr, mitigate AD pathology, but also suggests that identifying a specific constituent that mimics some of the benefits of these healthy diets could serve as a promising approach to discover new treatments for AD.

Structure-Based Virtual Screening and Biological Characterization of Novel BACE-1 and Amyloid-β Aggregation Inhibitors

Alzheimer's disease (AD) is a complex neurodegenerative disorder having limited treatment options. The beta-site APP cleaving enzyme 1 (BACE-1) is a key target for therapeutic intervention in Alzheimer's disease. To discover new scaffolds for BACE-1 inhibitors, a ChemBridge DIVERSet library of 20,000 small molecules was employed to structure-based virtual screening. The top 45 compounds, based on docking scores and binding affinities, were tested for BACE-1 inhibitory activity using a FRET assay. Four compounds, 18 (5353320), 20 (5262831), 29 (5784196) and 32 (5794006) demonstrated more than 35 % inhibitory activity at 10 μM. Notably, pyrazole-5-carbohydrazide 29 (5784196) exhibited BACE-1 inhibition with an IC50 value of 14.5 μM and a ki value of 0.25 μM. Additionally, it also inhibits the self-aggregation of β-amyloid, with IC50 value of 14.87 μM. Molecular modeling and dynamics simulations provided insights into its interaction pattern and stability of the enzyme-inhibitor complex. These findings suggest that virtual screening is an efficient and cost-effective method for identifying potential leads for AD.

Advanced nano delivery system for stem cell therapy for Alzheimer's disease

Alzheimer's Disease (AD) represents one of the most significant neurodegenerative challenges of our time, with its increasing prevalence and the lack of curative treatments underscoring an urgent need for innovative therapeutic strategies. Stem cells (SCs) therapy emerges as a promising frontier, offering potential mechanisms for neuroregeneration, neuroprotection, and disease modification in AD. This article provides a comprehensive overview of the current landscape and future directions of stem cell therapy in AD treatment, addressing key aspects such as stem cell migration, differentiation, paracrine effects, and mitochondrial translocation. Despite the promising therapeutic mechanisms of SCs, translating these findings into clinical applications faces substantial hurdles, including production scalability, quality control, ethical concerns, immunogenicity, and regulatory challenges. Furthermore, we delve into emerging trends in stem cell modification and application, highlighting the roles of genetic engineering, biomaterials, and advanced delivery systems. Potential solutions to overcome translational barriers are discussed, emphasizing the importance of interdisciplinary collaboration, regulatory harmonization, and adaptive clinical trial designs. The article concludes with reflections on the future of stem cell therapy in AD, balancing optimism with a pragmatic recognition of the challenges ahead. As we navigate these complexities, the ultimate goal remains to translate stem cell research into safe, effective, and accessible treatments for AD, heralding a new era in the fight against this devastating disease.

Alterations in the Processing of Platelet APP (Amyloid Beta Precursor Protein) in Alzheimer Disease: The Possible Nexus

Alzheimer's disease (AD) is the most common neurodegenerative disease associated with the development of dementia. The hallmarks of AD neuropathology are accumulations of amyloid peptide (Aβ) and neurofibrillary tangles (NFTs). Aβ is derived from the processing of APP (amyloid beta precursor protein) by BACE1 (beta-secretase 1) and γ-secretase through an amyloidogenic pathway. However, processing of APP by ADAM10/α-secretase (ADAM metallopeptidase domain 10) enzymes through a non-amyloidogenic pathway produces soluble APP alpha (sAPPα), which has a neuroprotective effect. It has been shown that activated platelets are implicated in the pathogenesis of AD, which also increases platelet activation. Under physiological conditions, platelets regulate synaptic plasticity and increase neuronal differentiation by regulation of the inflammatory response. However, overactivated platelets contribute to the pathogenesis of AD. Activated platelets represent the main source of circulating APP and Aβ that may be involved in AD neuropathology. Therefore, there is a close relationship between AD neuropathology and activated platelets. This review discusses the potential role of platelets in the pathogenesis of AD, and how targeting of activated platelets may reduce AD neuropathology.

Temperature-Dependent Aggregation of Tau Protein Is Attenuated by Native PLGA Nanoparticles Under in vitro Conditions

Introduction

Hyperphosphorylation and aggregation of the microtubule-associated tau protein, which plays a critical role in many neurodegenerative diseases (ie, tauopathies) including Alzheimer's disease (AD), are known to be regulated by a variety of environmental factors including temperature. In this study we evaluated the effects of FDA-approved poly (D,L-lactide-co-glycolic) acid (PLGA) nanoparticles, which can inhibit amyloid-β aggregation/toxicity in cellular/animal models of AD, on temperature-dependent aggregation of 0N4R tau isoforms in vitro.

Methods

We have used a variety of biophysical (Thioflavin T kinetics, dynamic light scattering and asymmetric-flow field-flow fractionation), structural (fluorescence imaging and transmission electron microscopy) and biochemical (Filter-trap assay and detection of soluble protein) approaches, to evaluate the effects of native PLGA nanoparticles on the temperature-dependent tau aggregation.

Results

Our results show that the aggregation propensity of 0N4R tau increases significantly in a dose-dependent manner with a rise in temperature from 27°C to 40°C, as measured by lag time and aggregation rate. Additionally, the aggregation of 2N4R tau increases in a dose-dependent manner. Native PLGA significantly inhibits tau aggregation at all temperatures in a concentration-dependent manner, possibly by interacting with the aggregation-prone hydrophobic hexapeptide motifs of tau. Additionally, native PLGA is able to trigger disassembly of preformed 0N4R tau aggregates as a function of temperature from 27°C to 40°C.

Conclusion

These results, taken together, suggest that native PLGA nanoparticles can not only attenuate temperature-dependent tau aggregation but also promote disassembly of preformed aggregates, which increased with a rise of temperature. Given the evidence that temperature can influence tau pathology, we believe that native PLGA may have a unique potential to regulate tau abnormalities associated with AD-related pathology.

Internalization of extracellular Tau oligomers in Alzheimer's disease

A key factor in the progression of Alzheimer's disease (AD) is internalization of extracellular Tau oligomers (ecTauOs) by neuroglial cells. Aberrant hyperphosphorylation of Tau results in their dissociation from microtubules and formation of toxic intracellular Tau oligomers (icTauOs). These are subsequently released to the extracellular space following neuronal dysfunction and death. Although receptor mediated internalization of these ecTauOs by other neurons, microglia and astrocytes can facilitate elimination, incomplete degradation thereof promotes inflammation, exacerbates pathologic spread and accelerates neurodegeneration. Targeting Tau oligomer degradation pathways, blocking internalization receptors, and mitigating neuroinflammation are proposed as therapeutic strategies to control Tau propagation and toxicity. This review highlights the urgent need for innovative approaches to prevent the spread of Tau pathology, emphasizing its implications for AD and related neurodegenerative diseases.

Deciphering the endogenous SUMO-1 landscape: a novel combinatorial peptide enrichment strategy for global profiling and disease association

Small ubiquitin-like modifier (SUMO) plays a pivotal role in diverse cellular processes and is implicated in diseases such as cancer and neurodegenerative disorders. However, large-scale identification of endogenous SUMO-1 faces challenges due to limited enrichment methods and its lower abundance compared to SUMO-2/3. Here we propose a novel combinatorial peptide strategy, combined with anti-adhesive polymer development, to enrich endogenous SUMO-1 modified peptides, revealing a comprehensive SUMOylation landscape. Utilizing phage display, we successfully identified a linear 12-mer and a cystine-linked cyclic 7-mer peptide ligand, specifically designed to target the C-terminal regions of SUMO-1 remnants. Building upon their high affinities and satisfactory complementarity, we developed the first artificial SUMO-1 enrichment materials, ultimately establishing a combinatorial peptide strategy that facilitates a comprehensive analysis of the endogenous SUMO-1 modified proteome in both cellular and tissue contexts. We successfully mapped 1312 SUMOylation sites in HeLa cells and 1365 along with 991 endogenous SUMOylation proteins in Alzheimer's disease (AD) mouse brain tissues. Notably, our method uncovered a significant upregulation of SUMO-1 in AD mouse brain tissue, providing new insights into SUMOylation's role in disease. Overall, this work represents the most thorough exploration of SUMO-1 modified proteomics and offers robust tools for elucidating the roles of SUMO-1's biological significance.

Microbial Trojan Horses: Virulence Factors as Key Players in Neurodegenerative Diseases

Changes in population demographics indicate that the elderly population will reach 2.1 billion worldwide by 2050. In parallel, there will be an increase in neurodegenerative diseases such as Alzheimer's and Parkinson's. This review explores dysbiosis occurring in these pathologies and how virulence factors contribute to the worsening or development of clinical conditions, and it summarizes existing and potential ways to combat microorganisms related to these diseases. Microbiota imbalances can contribute to the progression of neurodegenerative diseases by increasing intestinal permeability, exchanging information through innervation, and even acting as a Trojan horse affecting immune cells. The microorganisms of the microbiota produce virulence factors to protect themselves from host defenses, many of which contribute to neurodegenerative diseases. These virulence factors are expressed according to the genetic composition of each microorganism, leading to a wide range of factors to be considered. Among the main virulence factors are LPS, urease, curli proteins, amyloidogenic proteins, VacA, and CagA. These factors can also be packed into bacterial outer membrane vesicles, which transport proteins, RNA, and DNA, enabling distal communication that impacts various diseases, including Alzheimer's and Parkinson's.

Application of carbon-based nanomaterials in Alzheimer's disease

Alzheimer's disease (AD) is a chronic, progressive neurodegenerative disorder marked by permanent impairment of brain function across the whole brain. This condition results in a progressive deterioration of cognitive function in patients and is frequently associated with psychological symptoms such as agitation and anxiety, imposing a significant burden on both patients and their families. Nanomaterials possess numerous distinctive physical and chemical features that render them extensively utilized. In the biomedical domain, nanomaterials can be utilized for disease prevention and therapy, including medication delivery systems, biosensors, and tissue engineering. This article explores the etiology and potential molecular processes of AD, as well as the application of carbon-based nanomaterials in the diagnosis and treatment of AD. Some of such nanomaterials are carbon quantum dots, carbon nanotubes, and graphene, among others. These materials possess distinctive physicochemical features that render them highly promising for applications in biosensing, drug delivery, neuroprotection, and photothermal treatment. In addition, this review explored various therapeutic approaches for AD in terms of reducing inflammation, preventing oxidative damage, and inhibiting Aβ aggregation. The advent of carbon nanomaterials in nanotechnology has facilitated the development of novel treatment approaches for Alzheimer's disease. These strategies provide promising approaches for early diagnosis, effective intervention and neuroprotection of the disease.

Ganaxolone Reverses the Effect of Amyloid β-Induced Neurotoxicity by Regulating the Liver X Receptor Expression in APP Transfected SH-SY5Y Cells and Murine Model of Alzheimer's Disease

Inhibiting β-amyloid aggregation and enhancing its clearance are the key strategies in Alzheimer's disease (AD) treatment. Liver X receptors (LXRs) plays a crucial role in cholesterol homeostasis and inflammation, and their activation can clear Aβ aggregates in AD. Allopregnanolone, a neurosteroid, positively influences AD through LXR regulation, while ganaxolone, its synthetic analog, is known for its neuroprotective properties. This study explores the effect of ganaxolone on LXR activation and regulation of genes involved in mitigating Aβ toxicity and tauopathy in SH-SY5Y cells transfected with APP695 Swe/Ind plasmid and an Aβ1-42 induced AD mouse model. Molecular docking stimulations indicated ganaxolone's binding and interaction with LXRβ. Subsequently, transfected neuronal cells exhibited increased mRNA levels of APP, TNF-α and IL-1β, decreased cell viability, reduced MMP and altered protein expression of Aβ, LXR, BCL-2, APOE, ABCA1, along with increased levels of mROS, Bax, and caspase 3 activity. Ganaxolone treatment significantly abrogated Aβ-induced effect in transfected neuronal cells by enhancing LXRβ expression, inducing LXR:RXR colocalization, thereby increasing APOE and ABCA1 expression. It also decreased tau mRNA levels in transfected cells. Importantly, in AD mice, ganaxolone ameliorated cognitive impairment, reduced Aβ toxicity, tau levels, and neuroinflammatory markers, restored mitochondrial function, and decreased neuronal apoptosis. Taken together, these novel results highlight the central role of LXR in mediating Aβ-induced toxicity and provide preclinical evidence for ganaxolone as a potential agent to reduce toxicity in an LXR-dependent manner. This may serve as a promising treatment strategy to slow or prevent neurodegeneration in AD patients.

Association between Age-Related Macular Degeneration with Visual Disability and Risk of Dementia: A Nationwide Cohort Study

OBJECTIVES

To investigate the prospective association between the risk of dementia and age-related macular degeneration (AMD) in patients with related visual disability (VD).

DESIGN

A nationwide population-based cohort study used authorized data provided by the Korean National Health Insurance Service.

SETTING AND PARTICIPANTS

A total of 1,788,457 individuals aged >50 years who participated in the Korean National Health Screening Program were enrolled.

METHODS

From January 2009 to December 2019, participants were tracked for a diagnosis of dementia using registered diagnostic codes from claims data. Participants with VD were defined as those registered in a national disability registration established by the Korean government. The prospective association of AMD and related VD with new-onset dementia was investigated using a multivariate-adjusted Cox proportional hazard model adjusted for age, sex, body mass index, income level, systemic comorbidities, psychiatric diseases, and behavioral factors.

RESULTS

During the average follow-up period of 9.7 ± 2.16 years, 4260 of 21,384 participants in the AMD cohort and 137,166 of 1,662,319 participants in the control cohort were newly diagnosed with dementia, respectively. Participants diagnosed with AMD showed a higher risk of new-onset dementia than those in the control group in the fully adjusted model [hazard ratio (HR) 1.11, 95% CI 1.07-1.14]. The risk of dementia was higher in participants diagnosed with AMD and associated VD (HR 1.28, 95% CI 1.15-1.43) compared to those without VD (HR 1.09, 95% CI 1.06-1.13).

CONCLUSIONS AND IMPLICATIONS

A diagnosis of AMD was associated with an increased risk of all-cause dementia and its major subtypes. Close monitoring of cognitive function in patients with AMD, especially those with VD, may help in early detection of all-cause dementia, which could reduce the socioeconomic burden and improve the quality of life of patients.

Advanced Nanopharmaceutical Intervention for the Reduction of Inflammatory Responses and the Enhancement of Behavioral Outcomes in APP/PS1 Transgenic Mouse Models

Background: The excessive accumulation of Aβ plays a critical role in the development of Alzheimer's disease. However, the therapeutic potential of drugs like curcumin is often limited by low biocompatibility and BBB permeability. In this study, we developed a nanomaterial, BP-PEG-Tar@Cur, which was designed to enhance the biocompatibility of (curcumin) Cur, target Aβ, and augment BBB permeability through near-infrared (NIR) photothermal effects. Methods: Soluble Aβ, ThT fluorescence, and Aβ depolymerization fluorescence experiments were conducted to evaluate the ability of BP-PEG-Tar@Cur to inhibit Aβ aggregation and dissociate Aβ fibrils. Cell uptake assays were performed to confirm the targeting ability of BP-PEG-Tar@Cur towards Aβ. In vitro mitochondrial ROS clearance and in vivo detection of inflammatory factors were used to assess the anti-inflammatory and antioxidant properties of the nanodrug. Water maze behavioral experiments were conducted to evaluate the effect of BP-PEG-Tar@Cur on spatial memory, learning ability, and behavioral disorders in AD mice. Results: The nanodrug effectively inhibited Aβ aggregation and dissociated Aβ fibrils in vitro. BP-PEG-Tar@Cur demonstrated efficiency in curbing ROS overproduction in mitochondria and dampening the activation of microglia and astrocytes triggered by Aβ aggregation. Water maze behavioral experiments revealed that BP-PEG-Tar@Cur enhanced spatial memory, learning ability, and alleviated behavioral disorders in AD mice. Conclusions: Collectively, these findings demonstrate that BP-PEG-Tar@Cur has the potential to be an effective targeted drug for inhibiting Aβ aggregation and improving cognitive impairment in AD mice.

Evolving Landscape of Parkinson's Disease Research: Challenges and Perspectives

Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects movement. It occurs due to a gradual deficit of dopamine-producing brain cells, particularly in the substantia nigra. The precise etiology of PD is not fully understood, but it likely involves a combination of genetic and environmental factors. The therapies available at present alleviate symptoms but do not stop the disease's advancement. Research endeavors are currently directed at inventing disease-controlling therapies that aim at the inherent mechanisms of PD. PD biomarker breakthroughs hold enormous potential: earlier diagnosis, better monitoring, and targeted treatment based on individual response could significantly improve patient outcomes and ease the burden of this disease. PD research is an active and evolving field, focusing on understanding disease mechanisms, identifying biomarkers, developing new treatments, and improving care. In this report, we explore data from the CAS Content Collection to outline the research progress in PD. We analyze the publication landscape to offer perspective into the latest expertise advancements. Key emerging concepts are reviewed and strategies to fight disease evaluated. Pharmacological targets, genetic risk factors, as well as comorbid diseases are explored, and clinical usage of products against PD with their production pipelines and trials for drug repurposing are examined. This review aims to offer a comprehensive overview of the advancing landscape of the current understanding about PD, to define challenges, and to assess growth prospects to stimulate efforts in battling the disease.

Alterations in the inflammatory homeostasis of aging-related cardiac dysfunction and Alzheimer's diseases

Alzheimer's disease (AD) is well known among the elderly and has a profound impact on both patients and their families. Increasing research indicates that AD is a systemic disease, with a strong connection to cardiovascular disease. They share common genetic factors, such as mutations in the presenilin (PS1 and PS2) and the apolipoprotein E (APOE) genes. Cardiovascular conditions can lead to reduced cerebral blood flow and increased oxidative stress. These factors contribute to the accumulation of Aβ plaques and the formation of abnormal tau protein tangles, which are both key pathological features of AD. Additionally, Aβ deposits and abnormal protein responses have been observed in cardiomyocytes as well as in peripheral tissues. The toxic Aβ deposition intensifies damage to the microvascular structure associated with blood-brain barrier disruption and the initiation of neuroinflammation, which may accelerate the onset of neurocognitive deficits and cardiovascular dysfunction. Thus, we discuss the main mechanisms linking AD and cardiac dysfunction to enhance our understanding of these conditions. Ultimately, insights into the brain-heart axis may help us develop effective treatment strategies in the future.

Ferroptosis and pathogenesis of neuritic plaques in Alzheimer disease

Neuritic plaques are pathognomonic and terminal lesions of Alzheimer disease (AD). They embody AD pathogenesis because they harbor in one space critical pathologic features of the disease: amyloid deposits, neurofibrillary degeneration, neuroinflammation, and iron accumulation. Neuritic plaques are thought to arise from the conversion of diffuse extracellular deposits of amyloid-β protein (Aβ), and it is believed that during conversion, amyloid toxicity creates the dystrophic neurites of neuritic plaques, as well as neurofibrillary tangles However, recent evidence from human postmortem studies suggests a much different mechanism of neuritic plaque formation, where the first step in their creation is neuronal degeneration driven by iron overload and ferroptosis. Similarly, neurofibrillary tangles represent the corpses of iron-laden neurons that develop independently of Aβ deposits. In this review, we will focus on the role of free redox-active iron in the development of typical AD pathology, as determined largely by evidence obtained in the human temporal lobe during early, preclinical stages of AD. The findings have allowed the construction of a scheme of AD pathogenesis where brain iron is center stage and is involved in every step of the sequence of events that produce characteristic AD pathology. We will discuss how the study of preclinical AD has produced a fresh and revised assessment of AD pathogenesis that may be important for reconsidering current therapeutic efforts and guiding future ones. SIGNIFICANCE STATEMENT: This review offers a novel perspective on Alzheimer disease pathogenesis where elevated brain iron plays a central role and is involved throughout the development of lesions. Herein, we review arguments against the amyloid cascade theory and explain how recent findings in humans during early preclinical disease support iron-mediated cell death and endogenous iron containment mechanisms as critical components of neuritic plaque formation and ensuing dementia.

Bee Pollen as a Source of Biopharmaceuticals for Neurodegeneration and Cancer Research: A Scoping Review and Translational Prospects

Bee Pollen (BP) has many advantageous properties relying on its multitargeting potential, a new tendency in managing many challenging illnesses. In cancer and neurodegeneration, the multiple effects of BP could be of unequaled importance and need further investigation. Although still limited, available data interestingly spotlights some floral sources with promising activities in line with this investigation. Adopting scoping review methodology, we have identified many crucial bioactivities that are widely recognized to individual BP compounds but remain completely untapped in this valuable bee cocktail. A wide range of these compounds have been recently found to be endowed with great potential in modulating pivotal processes in neurodegeneration and cancer pathophysiology. In addition, some ubiquitous BP compounds have only been recently isolated, while the number of studied BPs remains extremely limited compared to the endless pool of plant species worldwide. We have also elucidated that clinical profits from these promising perspectives are still impeded by challenging hurdles such as limited bioavailability of the studied phytocompounds, diversity and lack of phytochemical standardization of BP, and the difficulty of selective targeting in some pathophysiological mechanisms. We finally present interesting insights to guide future research and pave the way for urgently needed and simplified clinical investigations.

Proteins Associated with Neurodegenerative Diseases: Link to DNA Repair

The nervous system is susceptible to DNA damage and DNA repair defects, and if DNA damage is not repaired, neuronal cells can die, causing neurodegenerative diseases in humans. The overall picture of what is known about DNA repair mechanisms in the nervous system is still unclear. The current challenge is to use the accumulated knowledge of basic science on DNA repair to improve the treatment of neurodegenerative disorders. In this review, we summarize the current understanding of the function of DNA damage repair, in particular, the base excision repair and double-strand break repair pathways as being the most important in nervous system cells. We summarize recent data on the proteins involved in DNA repair associated with neurodegenerative diseases, with particular emphasis on PARP1 and ND-associated proteins, which are involved in DNA repair and have the ability to undergo liquid-liquid phase separation.

Modulating Amyloid-β Toxicity: In Vitro Analysis of Aβ42(G37V) Variant Impact on Aβ42 Aggregation and Cytotoxicity

Alzheimer's disease (AD) is primarily driven by the formation of toxic amyloid-β (Aβ) aggregates, with Aβ42 being a pivotal contributor to disease pathology. This study investigates a novel agent to mitigate Aβ42-induced toxicity by co-assembling Aβ42 with its G37V variant (Aβ42(G37V)), where Gly at position 37 is substituted with valine. Using a combination of Thioflavin-T (Th-T) fluorescence assays, Western blot analysis, atomic force microscopy (AFM)/transmission electron microscopy (TEM), and biochemical assays, we demonstrated that adding Aβ42(G37V) significantly accelerates Aβ42 aggregation rate and mass while altering the morphology of the resulting aggregates. Consequently, adding Aβ42(G37V) reduces the Aβ42 aggregates-induced cytotoxicity, as evidenced by improved cell viability assays. The possible mechanism for this effect is that adding Aβ42(G37V) reduces the production of reactive oxygen species (ROS) and lipid peroxidation, typically elevated in response to Aβ42, indicating its protective effects against oxidative stress. These findings suggest that Aβ42(G37V) could be a promising candidate for modulating Aβ42 aggregation dynamics and reducing its neurotoxic effects, providing a new avenue for potential therapeutic interventions in AD.

Effects of the therapeutic correction of U1 snRNP complex on Alzheimer's disease

The U1 snRNP complex recognizes pre-mRNA splicing sites in the early stages of spliceosome assembly and suppresses premature cleavage and polyadenylation. Its dysfunction may precede Alzheimer's disease (AD) hallmarks. Here we evaluated the effects of a synthetic single-stranded cDNA (APT20TTMG) that interacts with U1 snRNP, in iPSC-derived neurons from a donor diagnosed with AD and in the SAMP8 mouse model. APT20TTMG effectively binds to U1 snRNP, specifically decreasing TAU in AD neurons, without changing mitochondrial activity or glutamate. Treatment enhanced neuronal electrical activity, promoted an enrichment of differentially expressed genes related to key processes affected by AD. In SAMP8 mice, APT20TTMG reduced insoluble pTAU in the hippocampus, amyloid-beta and GFAP in the cortex, and U1-70 K in both brain regions, without cognitive changes. This study highlights the correction of the U1 snRNP complex as a new target for AD.

Asymmetrical patterns of β-amyloid deposition and cognitive changes in Alzheimer's disease: the SILCODE study

The asymmetric pattern of β-amyloid plaque distribution across Alzheimer's disease clinical progression stages remains unclear. In this study, 66 participants with normal cognition, 59 with subjective cognitive decline, 12 with mild cognitive impairment, and 11 with Alzheimer's disease dementia were included in the Sino Longitudinal Study on Cognitive Decline (SILCODE) cohort. A regional asymmetry index, denoting the left-right asymmetry of β-amyloid plaques, was derived for each region based on the Anatomical Automatic Labeling atlas. The level of β-amyloid plaques in each region was compared among different clinical stages of Alzheimer's disease using the analysis of variance. An additional correlation analysis examined the relationship between each region of interest's cognitive performance scores and asymmetry index values. We found that β-amyloid appears to be lateralized in different stages of Alzheimer's disease. In addition, there is a significant correlation between β-amyloid asymmetry in various brain regions and cognition. The observed Aβ lateralization could potentially be utilized as a neuroimaging biomarker throughout AD progression.

Common and divergent pathways in early stages of glutamate and tau-mediated toxicities in neurodegeneration

It has been shown that excitotoxicity and tau-mediated toxicities are major contributing factors to neuronal death in Alzheimer's disease (AD). The excitatory amino acid transporter 2 (EAAT2 or GLT-1), the major glutamate transporter in the brain that regulates glutamate levels synaptically and extrasynaptically, has been shown to be deficient in AD brains, leading to excitotoxicity and subsequent cell death. Similarly, buildup of neurofibrillary tangles, which consist of hyperphosphorylated tau protein, correlates with cognitive decline and neuronal atrophy in AD. However, common genes and pathways that are critical in the aforementioned toxicities have not been well elucidated. To investigate the impact of glutamate dyshomeostasis and tau accumulation on translational profiles of affected hippocampal neurons, we used mouse models of excitotoxicity and tau-mediated toxicities (GLT-1-/- and P301S, respectively) in conjunction with BAC-TRAP technology. Our data show that GLT-1 deficiency in CA3 pyramidal neurons leads to translational signatures characterized by dysregulation of pathways associated with synaptic plasticity and neuronal survival, while the P301S mutation induces changes in endocytic pathways and mitochondrial dysfunction. Finally, the commonly dysregulated pathways include impaired ion homeostasis and metabolic pathways. These common pathways may shed light on potential therapeutic targets for ameliorating glutamate and tau-mediated toxicities in AD.

Amyloid-β and phosphorylated tau screening in bottlenose dolphin (Tursiops truncatus) and striped dolphin (Stenella coeruleoalba) brains from Italy reveals distinct immunohistochemical patterns correlating with age and co-morbidity

Cetacean brains are uniquely adapted to diving, but can be affected by diseases and exposure to toxins, triggering neurodegenerative processes that may cause stranding. Some species exhibit a significant post-reproductive lifespan (PRLS), increasing the likelihood of observing cumulative and age-related pathology. Immunohistochemistry against amyloid-β and hyperphosphorylated tau proteins is increasingly implemented to assess Alzheimer's Disease-like neuropathology in cetaceans, but comparisons between geographically distinct populations, animals of different age groups, sex, and with concomitant pathologies are lacking. We tested 43 cetaceans' (30 Tursiops truncatus; 13 Stenella coeruleoalba) parietal cortex, our most consistently archived cerebral tissue, in immunohistochemical analyses with amyloid-β oligomer 42 (Aβ-42) and hyperphosphorylated tau (pTau AT180 and AT8) antibodies. Aβ-42 antibody cross-reacted with plaques in three aged bottlenose and two aged striped dolphins, but was more often detected within neurons, glia, and blood vessels of all the dolphins. Histoscore comparisons between dolphins of different ages, sexes, and pathologies revealed significant correlations between older age, viral infections, and plaque presence. Protozoan cysts cross-reacted with Aβ-42 antibody. pTau signal was observed as single foci in neurons and neuropil in two young and two aged bottlenose dolphins. To our knowledge, this study is the first of its kind for the Mediterranean region and will help establish baseline understanding of physiological and pathological expression of proteins associated with human neurodegenerative disease in cetacean brains.

Depression like-behavior and memory loss induced by methylglyoxal is associated with tryptophan depletion and oxidative stress: a new in vivo model of neurodegeneration

BACKGROUND

Depression and memory loss are prevalent neurodegenerative disorders, with diabetic patients facing an elevated risk of brain dysfunction. Methylglyoxal (MGO) formation, which is heightened in diabetes owing to hyperglycemia and gut dysbiosis, may serve as a critical link between diabetes and brain diseases. Despite the high prevalence of MGO, the precise mechanisms underlying MGO-induced depression and memory loss remain unclear.

RESULTS

We investigated the effect of MGO stress on depression like-behavior and memory loss to elucidate the potential interplay between MGO-induced tryptophan (Trp) metabolism impairment and oxidative stress in the brain. It demonstrates that MGO induces depression-like behavior in mice, as confirmed by the OFT, TST, FST, SPT, and EPM behavioral tests. MGO led to the depletion of Trp and related neurotransmitters as 5-HT, EPI, and DA in the mouse brain. Additionally, MGO reduced the cell count in the DG, CA1, and CA3 hippocampal regions and modulated TPH2 levels in the brain. Notably, co-treatment with MGO and Trp mirrored the effects observed after Trp-null treatment in neurons, including reduced TPH1 and TPH2 levels and inhibition of neuronal outgrowth. Furthermore, MGO significantly altered the expression of key proteins associated with neurodegeneration, such as p-Tau, p-GSK-3β, APP, oAβ, BDNF, NGF, and p-TrkB. Concurrently, MGO activated MAPKs through ROS induction, triggering a redox imbalance by downregulating Nrf-2, Ho-1, TXNRD1, Trx, Sirt-3, and Sirt-5 expression levels, NAD+, and CAT activity in the mouse brain. This led to an accelerated neuroinflammatory response, as evidenced by increased expression of Iba-1, p-NF-κB, and the secretion of IL-6 and TNF-α. Importantly, Trp treatment ameliorated MGO-induced depression like-behavior and memory loss in mice and markedly mitigated increased expression of p-Tau, APP, p-ERK1/2, p-pJNK, and p-NF-κB in the brain. Likewise, Trp treatment also induced the expression of MGO detoxifying factors GLO-I and GLO-II and CAT activity, suggesting the induction of an antioxidant system and reduced inflammation by inhibiting IL-6 and TNF-α secretion.

CONCLUSIONS

Our data revealed that MGO-induced depression like-behavior and memory deficits resulted from disturbances in Trp, 5-HT, BDNF, and NGF levels, increased p-Tau and APP expression, neuroinflammation, and impaired redox status (Nrf-2/Ho-1/TXNRD1/Sirt3/5) in the brain.

Stem cell therapy in Alzheimer's disease: current status and perspectives

An incurable neurogenerative illness, Alzheimer's disease, is the cause of most global health, medical, and social disasters. The two main symptoms are cognitive impairment and neuronal loss. Current medications that target tau protein tangles and Aβ plaques are not very effective because they only slow the symptoms of AD and do not repair damaged cells. Stem cell-based treatments, however, present an alternative strategy in the treatment of AD. They have the capacity to divide into specialized adult cells, have self-renewal abilities, and multiplication. Stem cells can now be employed as a donor source for cell therapy due to developments in stem cell technology. This review covers preclinical and clinical updates on studies based on targeting the tau protein tangles and Aβ plaque, as well as four types of stem cells employed in AD treatment. The review also outlines the two basic pathologic aspects, tau protein tangles and Aβ plaques, of AD.

Exploring the Connection Between Nanomaterials and Neurodegenerative Disorders

Drug delivery, tissue engineering, and cell promotion in biomedical fields heavily rely on the use of nanomaterials (NMs). When they penetrate cells, NPs undergo degradation and initiate the generation of reactive oxygen species (ROS) by causing changes in the structures of organelles linked to mitochondria. Inside the cell, the excess production of ROS can initiate a chain reaction, along with the autophagy process that helps maintain ROS balance by discarding unnecessary materials. At present, there is no effective treatment for Alzheimer's disease (AD), a progressive neurodegenerative disease. The use of NMs for siRNA delivery could become a promising treatment for AD and other CNS disorders. Recent research demonstrates that the use of combined NPs can induce autophagy in cells. This article emphasizes the importance of the shape of siRNA-encapsulated NMs in determining their efficiency in delivering and suppressing gene activity in the central nervous system. Because of its strict selectivity against foreign substances, the blood-brain barrier (BBB) significantly hinders the delivery of therapeutic agents to the brain. Conventional chemotherapeutic drugs are significantly less effective against brain cancers due to this limitation. As a result, NMs have become a promising approach for targeted drug delivery, as they can be modified to carry specific ligands that direct them to their intended targets. This review thoroughly examines the latest breakthroughs in using NMs to deliver bioactive compounds across the BBB, focusing on their use in cancer treatments. The review starts by examining the structure and functions of the BBB and BBTB, and then emphasizes the benefits that NMs offer.

Untangling the role of tau in sex hormone responsive cancers: lessons learnt from Alzheimer's disease

Tubulin associated unit has been extensively studied in neurodegenerative diseases including Alzheimer's disease (AD), whereby its hyperphosphorylation and accumulation contributes to disease pathogenesis. Tau is abundantly expressed in the central nervous system but is also present in non-neuronal tissues and in tumours including sex hormone responsive cancers such as breast and prostate. Curiously, hormonal effects on tau also exist in an AD context from numerous studies on menopause, hormone replacement therapy, and androgen deprivation therapy. Despite sharing some risk factors, most importantly advancing age, there are numerous reports from population studies of, currently poorly explained inverse associations between cancer and Alzheimer's disease. We previously reviewed important components of the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) signalling pathway and their differential modulation in relation to the two diseases. Similarly, receptor tyrosine kinases, estrogen receptor and androgen receptor have all been implicated in the pathogenesis of both cancer and AD. In this review, we focus on tau and its effects in hormone responsive cancer in terms of development, progression, and treatment and in relation to sex hormones and PI3K/Akt signalling molecules including IRS-1, PTEN, Pin1, and p53.

Role of astrocytes in Alzheimer's disease pathogenesis and the impact of exercise-induced remodeling

Alzheimer's disease (AD) is a prevalent and debilitating brain disorder that worsens progressively with age, characterized by cognitive decline and memory impairment. The accumulation of amyloid-beta (Aβ) leading to amyloid plaques and hyperphosphorylation of Tau, resulting in intracellular neurofibrillary tangles (NFTs), are primary pathological features of AD. Despite significant research investment and effort, therapies targeting Aβ and NFTs have proven limited in efficacy for treating or slowing AD progression. Consequently, there is a growing interest in non-invasive therapeutic strategies for AD prevention. Exercise, a low-cost and non-invasive intervention, has demonstrated promising neuroprotective potential in AD prevention. Astrocytes, among the most abundant glial cells in the brain, play essential roles in various physiological processes and are implicated in AD initiation and progression. Exercise delays pathological progression and mitigates cognitive dysfunction in AD by modulating astrocyte morphological and phenotypic changes and fostering crosstalk with other glial cells. This review aims to consolidate the current understanding of how exercise influences astrocyte dynamics in AD, with a focus on elucidating the molecular and cellular mechanisms underlying astrocyte remodeling. The review begins with an overview of the neuropathological changes observed in AD, followed by an examination of astrocyte dysfunction as a feature of the disease. Lastly, the review explores the potential therapeutic implications of exercise-induced astrocyte remodeling in the context of AD.

A systematic review of the efficacy and safety of anti-amyloid beta monoclonal antibodies in treatment of Alzheimer's disease

INTRODUCTION

Alzheimer's disease can cause dementia through brain matter degradation. This study investigates the monoclonal antibody usage for AD treatment, following PRISMA 2020 guidelines, and aims to discern the monoclonal antibody that offers the optimal balance of efficacy and safety for individuals with AD.

METHODS

A systematic search was conducted across databases such as PubMed, Cochrane Library, and clinical trial registries for randomized controlled trials. The quality of studies was assessed using the Cochrane risk of bias 2 tool. Cognitive function and daily activities were evaluated using MMSE, ADAS-Cog, and CDR-SB test data.

RESULTS

According to CDR-SB measurements, lecanemab showed effectiveness in reducing brain amyloid and cognitive decline, with a change from baseline of 1.21. Aducanumab resulted in a decrease of -0.39 (-22%). Bapineuzumab showed no significant benefit, with scores of 2.4 (2.8). Gantenerumab, scoring 1.69 (1.37, 2.01), reduces amyloid, particularly in early Alzheimer's stages. Crenezumab was ineffective, with a score of 3.61.

CONCLUSION

The findings provide various perspectives. Lecanemab showed the most promise in brain amyloid reduction and decelerating cognitive decline compared to the other therapies. Further research is needed, highlighting the necessity of AD therapeutic research to alter AD's trajectory and provide reliable treatment.

PROTOCOL REGISTRATION

www.crd.york.ac.uk/prospero identifier is CRD42024504358.

Activation of autophagy by Citri Reticulatae Semen extract ameliorates amyloid-beta-induced cell death and cognition deficits in Alzheimer's disease

JOURNAL/nrgr/04.03/01300535-202419110-00027/figure1/v/2024-03-08T184507Z/r/image-tiff Amyloid-beta-induced neuronal cell death contributes to cognitive decline in Alzheimer's disease. Citri Reticulatae Semen has diverse beneficial effects on neurodegenerative diseases, including Parkinson's and Huntington's diseases, however, the effect of Citri Reticulatae Semen on Alzheimer's disease remains unelucidated. In the current study, the anti-apoptotic and autophagic roles of Citri Reticulatae Semen extract on amyloid-beta-induced apoptosis in PC12 cells were first investigated. Citri Reticulatae Semen extract protected PC12 cells from amyloid-beta-induced apoptosis by attenuating the Bax/Bcl-2 ratio via activation of autophagy. In addition, Citri Reticulatae Semen extract was confirmed to bind amyloid-beta as revealed by biolayer interferometry in vitro, and suppress amyloid-beta-induced pathology such as paralysis, in a transgenic Caenorhabditis elegans in vivo model. Moreover, genetically defective Caenorhabditis elegans further confirmed that the neuroprotective effect of Citri Reticulatae Semen extract was autophagy-dependent. Most importantly, Citri Reticulatae Semen extract was confirmed to improve cognitive impairment, neuronal injury and amyloid-beta burden in 3×Tg Alzheimer's disease mice. As revealed by both in vitro and in vivo models, these results suggest that Citri Reticulatae Semen extract is a potential natural therapeutic agent for Alzheimer's disease via its neuroprotective autophagic effects.

Effects of exercise on brain-derived neurotrophic factor in Alzheimer's disease models: A systematic review and meta-analysis

A growing body of research examining effects of exercise on brain-derived neurotrophic factor (BDNF) in Alzheimer's disease (AD) models, while due to differences in gender, age, disease severity, brain regions examined, and type of exercise intervention, findings of available studies were conflicting. In this study, we aimed to evaluate current evidence regarding effects of exercise on BDNF in AD models. Searches were performed in PubMed, Web of Science, Cochrane, and EBSCO electronic databases, through July 20, 2023. We included studies that satisfied the following criteria: eligible studies should (1) report evidence on experimental work with AD models; (2) include an exercise group and a control group (sedentary); (3) use BDNF as the outcome indicator; and (4) be randomized controlled trials (RCTs). From 1196 search records initially identified, 36 studies met the inclusion criteria. There was a significant effect of exercise on increasing BDNF levels in AD models [standardized mean differences (SMD) = 0.98, P < 0.00001]. Subgroup analysis showed that treadmill exercise (SMD = 0.92, P< 0.0001), swimming (SMD = 1.79, P< 0.0001), and voluntary wheel running (SMD = 0.51, P= 0.04) were all effective in increasing BDNF levels in AD models. In addition, exercise significantly increased BDNF levels in the hippocampus (SMD = 0.92, P< 0.00001) and cortex (SMD = 1.56, P= 0.02) of AD models. Exercise, especially treadmill exercise, swimming, and voluntary wheel running, significantly increased BDNF levels in hippocampus and cortex of AD models, with swimming being the most effective intervention type.

Nicotinic and Muscarinic Acetylcholine Receptor Agonists Counteract Cognitive Impairment in a Rat Model of Doxorubicin-Induced Chemobrain via Attenuation of Multiple Programmed Cell Death Pathways

Chemotherapy causes undesirable long-term neurological sequelae, chemotherapy-induced cognitive impairment (CICI), or chemobrain in cancer survivors. Activation of programmed cell death (PCD) has been proposed to implicate in the development and progression of chemobrain. Neuronal apoptosis has been extensively recognized in experimental models of chemobrain, but little is known about alternative forms of PCD in response to chemotherapy. Activation of acetylcholine receptors (AChRs) is emerging as a promising target in attenuating a wide variety of the neuronal death associated with neurodegeneration. Thus, this study aimed to investigate the therapeutic capacity of AChR agonists on cognitive function and molecular hallmarks of multiple PCD against chemotherapy neurotoxicity. To establish the chemobrain model, male Wistar rats were assigned to receive six doses of doxorubicin (DOX: 3 mg/kg) via intraperitoneal injection. The DOX-treated rats received either an a7nAChR agonist (PNU-282987: 3 mg/kg/day), mAChR agonists (bethanechol: 12 mg/kg/day), or the two as a combined treatment. DOX administration led to impaired cognitive function via neuroinflammation, glial activation, reduced synaptic/blood-brain barrier integrity, defective mitochondrial ROS-detoxifying capacity, and dynamic imbalance. DOX insult also mediated hyperphosphorylation of Tau and simultaneously induced various PCD, including apoptosis, necroptosis, and pyroptosis in the hippocampus. Concomitant treatment with either PNU-282987, bethanechol, or a combination of the two potently attenuated neuroinflammation, mitochondrial dyshomeostasis, and Tau hyperphosphorylation, thereby suppressing excessive apoptosis, necroptosis, and pyroptosis and improving cognitive function in DOX-treated rats. Our findings suggest that activation of AChRs using their agonists effectively protected against DOX-induced neuronal death and chemobrain.

Cellular and pathological functions of tau

Tau protein is involved in various cellular processes, including having a canonical role in binding and stabilization of microtubules in neurons. Tauopathies are neurodegenerative diseases marked by the abnormal accumulation of tau protein aggregates in neurons, as seen, for example, in conditions such as frontotemporal dementia and Alzheimer disease. Mutations in tau coding regions or that disrupt tau mRNA splicing, tau post-translational modifications and cellular stress factors (such as oxidative stress and inflammation) increase the tendency of tau to aggregate and interfere with its clearance. Pathological tau is strongly implicated in the progression of neurodegenerative diseases, and the propagation of tau aggregates is associated with disease severity. Recent technological advancements, including cryo-electron microscopy and disease models derived from human induced pluripotent stem cells, have increased our understanding of tau-related pathology in neurodegenerative conditions. Substantial progress has been made in deciphering tau aggregate structures and the molecular mechanisms that underlie protein aggregation and toxicity. In this Review, we discuss recent insights into the diverse cellular functions of tau and the pathology of tau inclusions and explore the potential for therapeutic interventions.

Qifu-yin activates the Keap1/Nrf2/ARE signaling and ameliorates synaptic injury and oxidative stress in APP/PS1 mice

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional medicinal formulation, Qifu-yin (QFY), has been widely prescribed for Alzheimer's disease (AD) treatment in China, yet the comprehensive mechanisms through which QFY mitigates AD pathology remain to be fully delineated.

AIM OF THE STUDY

This study aimed to explore the therapeutic implications of QFY on the synaptic injury and oxidative stress in the hippocampus of APPswe/PS1dE9 (APP/PS1) mice, with a concerted effort to elucidate the molecular mechanisms related to synaptic preservation and memory improvement.

MATERIALS AND METHODS

The components of QFY were identified by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The neuroprotective effects of QFY was evaluated using six-month-old male APP/PS1 mice. Subsequent to a 15 days of QFY regimen, spatial memory was assessed utilizing the Morris water maze (MWM) test. Amyloid-beta (Aβ) aggregation was detected via immunostaining, while the quantification of Aβ1-40 and Aβ1-42 was achieved through enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was used to investigate the synaptic structure and mitochondrial morphology. Golgi staining was applied to examine dendritic spine density. Reactive oxygen species (ROS), 3-nitrotyrosine (3-NT) and 4-hydroxy-nonenal (4-HNE) assays were employed to assess oxidative stress. The expression profiles of Aβ metabolism-associated enzymes and the Keap1/Nrf2/ARE signaling pathway were determined by Western blot.

RESULTS

A total of 20 principal compounds in QFY were identified. QFY mitigated memory deficits of APP/PS1 mice, including reducing escape latency and search distance and increasing the time and distance spent in the target quadrant. In addition, QFY increased platform crossings of APP/PS1 mice in the probe trial of MWM tests. TEM analysis showed that QFY increased synapse number in the CA1 region of APP/PS1 mice. Further studies indicated that QFY elevated the expression levels of Post synaptic density protein 95 (PSD95) and synaptophysin, and mitigated the loss of dendritic spine density in the hippocampus of APP/PS1 mice. QFY has been shown to ameliorated the structural abnormalities of mitochondria, including mitochondrial dissolution and degradation, up-regulate ATP synthesis and membrane potential in the hippocampus of APP/PS1 mice. Moreover, QFY activated the Keap1/Nrf2/ARE signaling pathway in the hippocampus of APP/PS1 mice, which might contribute to the neuroprotective effects of QFY.

CONCLUSION

QFY activates the Keap1/Nrf2/ARE signaling, and protects against synaptic and mitochondrial dysfunction in APP/PS1 mice, proposing a potential alternative therapeutic strategy for AD management.

Blood-Based Biomarkers in Alzheimer's Disease: Advancing Non-Invasive Diagnostics and Prognostics

Alzheimer's disease (AD), the most prevalent form of dementia, is expected to rise dramatically in incidence due to the global population aging. Traditional diagnostic approaches, such as cerebrospinal fluid analysis and positron emission tomography, are expensive and invasive, limiting their routine clinical use. Recent advances in blood-based biomarkers, including amyloid-beta, phosphorylated tau, and neurofilament light, offer promising non-invasive alternatives for early AD detection and disease monitoring. This review synthesizes current research on these blood-based biomarkers, highlighting their potential to track AD pathology and enhance diagnostic accuracy. Furthermore, this review uniquely integrates recent findings on protein-protein interaction networks and microRNA pathways, exploring novel combinations of proteomic, genomic, and epigenomic biomarkers that provide new insights into AD's molecular mechanisms. Additionally, we discuss the integration of these biomarkers with advanced neuroimaging techniques, emphasizing their potential to revolutionize AD diagnostics. Although large-scale validation is still needed, these biomarkers represent a critical advancement toward more accessible, cost-effective, and early diagnostic tools for AD.

Increases in amyloid-β42 slow cognitive and clinical decline in Alzheimer's disease trials

Positive effects of new anti-amyloid-β (Aβ) monoclonal antibodies in Alzheimer's disease (AD) have been attributed to brain amyloid reduction. However, most anti-Aβ antibodies also increase the CSF levels of the 42-amino acid isoform (Aβ42). We evaluated the associations of changes in CSF Aβ42 and brain Aβ-PET with cognitive and clinical end points in randomized trials of anti-Aβ drugs that lowered (β- and γ-secretase inhibitors) or increased CSF Aβ42 levels (anti-Aβ monoclonal antibodies) to test the hypothesis that post-treatment increases in CSF Aβ42 levels are independently associated with cognitive and clinical outcomes. From long-term (≥12 months) randomized placebo-controlled clinical trials of anti-Aβ drugs published until November 2023, we calculated the post-treatment versus baseline difference in ADAS-Cog (cognitive subscale of the Alzheimer's Disease Assessment Scale) and CDR-SB (Clinical Dementia Rate-Sum of Boxes) and z-standardized changes in CSF Aβ42 and Aβ-PET Centiloids (CL). We estimated the effect size [regression coefficients (RCs) and confidence intervals (CIs)] and the heterogeneity (I2) of the associations between AD biomarkers and cognitive and clinical end points using random-effects meta-regression models. We included 25 966 subjects with AD from 24 trials. In random-effects analysis, increases in CSF Aβ42 were associated with slower decline in ADAS-Cog (RC: -0.55; 95% CI: -0.89, -0.21, P = 0.003, I2 = 61.4%) and CDR-SB (RC: -0.16; 95% CI: -0.26, -0.06, P = 0.002, I2 = 34.5%). Similarly, decreases in Aβ-PET were associated with slower decline in ADAS-Cog (RC: 0.69; 95% CI: 0.48, 0.89, P < 0.001, I2 = 0%) and CDR-SB (RC: 0.26; 95% CI: 0.18, 0.33, P < 0.001, I2 = 0%). Sensitivity analyses yielded similar results. Higher CSF Aβ42 levels after exposure to anti-Aβ drugs are independently associated with slowing cognitive impairment and clinical decline. Increases in Aβ42 may represent a mechanism of potential benefit of anti-Aβ monoclonal antibodies in AD.