Anti-amyloid antibody therapies in Alzheimer's disease

Association of diabetes mellitus with dementia- and non-dementia-related mortality amongst women: a secondary competing risks analysis of the California Teachers Study

BACKGROUND AND PURPOSE

The prevalence of dementia is rapidly increasing. Attempts to further understand modifiable risk factors such as diabetes mellitus (DM) are urgently needed to inform public health policies for prevention. Thus, the objective of the current study was to assess the relationship between DM and risk of dementia and non-dementia mortality amongst women in the California Teachers Study prospective cohort.

METHODS

Women (n = 124,509) aged 22-104 years at baseline were included. DM was ascertained from self-reported questionnaires and hospital-linked records. Dementia-related deaths were ascertained from state and national records. Competing risk regression models were used to estimate cause-specific hazard ratios and 95% confidence intervals for the association of DM with dementia- and non-dementia-related mortality.

RESULTS

There were 10,511 total DM cases and 3625 deaths due to dementia over a mean of 21.3 years of follow-up. Fully adjusted cause-specific hazard ratios of the association with DM were 2.26 (2.01, 2.55) for dementia-related and 1.97 (1.89, 2.05) for the competing risk of non-dementia-related mortality. This association was strongest amongst participants with incident DM, younger age at baseline and higher alcohol consumption or who were overweight.

CONCLUSIONS

In the California Teachers Study, women with DM had increased risk of mortality due to both dementia and non-dementia causes; however, the risk of mortality due to dementia was elevated compared to non-dementia causes only amongst participants with incident DM.

Redesigning the kinetics of lysozyme amyloid aggregation by cephalosporin molecules

In lysozyme amyloidosis, fibrillar aggregates of lysozyme are associated with severe renal, hepatic, and gastrointestinal manifestations, with no definite therapy. Current drugs are now being tested in amyloidosis clinical trials as aggregation inhibitors to mitigate disease progression. The tetracycline group among antimicrobials in use is in phase II of clinical trials, whereas some macrolides and cephalosporins have shown neuroprotection. In the present study, two cephalosporins, ceftazidime (CZD) and cefotaxime (CXM), and a glycopeptide, vancomycin (VNC), are evaluated for inhibition of amyloid aggregation of hen egg white lysozyme (HEWL) under two conditions (i) 4 M guanidine hydrochloride (GuHCl) at pH 6.5 and 37° C, (ii) At pH 1.5 and 65 °C. Fluorescence quench titration and molecular docking methods report that CZD, CXM, and VNC interact more strongly with the partially folded intermediates (PFI) in comparison to the protein's natural state (N). However, only CZD and CXM proficiently inhibit the aggregation. Transmission electron microscopy, tinctorial assessments, and aggregation kinetics all support oligomer-level inhibition. Transition structures in CZD-HEWL and CXM-HEWL aggregation are shown by circular dichroism (CD). On the other hand, kinetic variables and soluble fraction assays point to a localized association of monomers. Intrinsic fluorescence (IF),1-Anilino 8-naphthalene sulphonic acid, and CD demonstrate structural and conformational modifications redesigning the PFI. GuHCl-induced unfolding and differential scanning fluorimetry suggested that the PFI monomers bound to CZD and CXM exhibited partial stability. Our results present two mechanisms that function in both solution conditions, creating a novel avenue for the screening of putative inhibitors for drug repurposing. We extend our proposed mechanisms in the designing of physical inhibitors of amyloid aggregation considering shorter time frames and foolproof methods.Communicated by Ramaswamy H. Sarma.

Co-Assembled Nanoparticles toward Multi-Target Combinational Therapy of Alzheimer's Disease by Making Full Use of Molecular Recognition and Self-Assembly

The complex pathologies in Alzheimer's disease (AD) severely limit the effectiveness of single-target pharmic interventions, thus necessitating multi-pronged therapeutic strategies. While flexibility is essentially demanded in constructing such multi-target systems, for achieving optimal synergies and also accommodating the inherent heterogeneity within AD. Utilizing the dynamic reversibility of supramolecular strategy for conferring sufficient tunability in component substitution and proportion adjustment, amphiphilic calixarenes are poised to be a privileged molecular tool for facilely achieving function integration. Herein, taking β-amyloid (Aβ) fibrillation and oxidative stress as model combination pattern, a supramolecular multifunctional integration is proposed by co-assembling guanidinium-modified calixarene with ascorbyl palmitate and loading dipotassium phytate within calixarene cavity. Serial pivotal events can be simultaneously addressed by this versatile system, including 1) inhibition of Aβ production and aggregation, 2) disintegration of Aβ fibrils, 3) acceleration of Aβ metabolic clearance, and 4) regulation of oxidative stress, which is verified to significantly ameliorate the cognitive impairment of 5×FAD mice, with reduced Aβ plaque content, neuroinflammation, and neuronal apoptosis. Confronted with the extremely intricate clinical realities of AD, the strategy presented here exhibits ample adaptability for necessary alterations on combinations, thereby may immensely expedite the advancement of AD combinational therapy through providing an exceptionally convenient platform.

Multiple system atrophy with amyloid-β-predominant Alzheimer's disease neuropathologic change

Multiple system atrophy is a neurodegenerative disease with α-synuclein pathology predominating in the striatonigral and olivopontocerebellar systems. Mixed pathologies are considered to be of low frequency and mostly comprise primary age-related tauopathy or low levels of Alzheimer's disease-related neuropathologic change. Therefore, the concomitant presence of different misfolded proteins in the same brain region is less likely in multiple system atrophy. During the neuropathological evaluation of 21 consecutive multiple system atrophy cases, we identified four cases exhibiting an unusual discrepancy between high Thal amyloid-β phase and low transentorhinal Braak neurofibrillary tangle stage. We mapped α-synuclein pathology, measured the size and number of glial cytoplasmic inclusions and compared the amyloid-β peptides between multiple system atrophy and Alzheimer's disease. In addition, we performed α-synuclein seeding assay from the affected putamen samples. We performed genetic testing for APOE, MAPT, PSEN1, PSEN2 and APP. We refer to the four multiple system atrophy cases with discrepancy between amyloid-β and tau pathology as 'amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy' to distinguish these from multiple system atrophy with primary age-related tauopathy or multiple system atrophy with typical Alzheimer's disease neuropathologic change. As most multiple system atrophy cases with mixed pathologies reported in the literature, these cases did not show a peculiar clinical or MRI profile. Three amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy cases were available for genetic testing, and all carried the APOE ɛ4 allele. The extent and severity of neuronal loss and α-synuclein pathology were not different compared with typical multiple system atrophy cases. Analysis of amyloid-β peptides revealed more premature amyloid-β plaques in amyloid-β-predominant Alzheimer's disease neuropathologic change-multiple system atrophy compared with Alzheimer's disease. α-Synuclein seeding amplification assay showed differences in the kinetics in two cases. This study highlights a rare mixed pathology variant of multiple system atrophy in which there is an anatomical meeting point of amyloid-β and α-synuclein, i.e. the striatum or cerebellum. Since biomarkers are entering clinical practice, these cases will be recognized, and the clinicians have to be informed that the prognosis is not necessarily different than in pure multiple system atrophy cases but that the effect of potential α-synuclein-based therapies might be influenced by the co-presence of amyloid-β in regions where α-synuclein also aggregates. We propose that mixed pathologies should be interpreted not only based on differences in the clinical phenotype but also on whether protein depositions regionally overlap, potentially leading to a different response to α-synuclein-targeted therapies.

Addition of inflammation-related biomarkers to the CAIDE model for risk prediction of all-cause dementia, Alzheimer's disease and vascular dementia in a prospective study

BACKGROUND

It is of interest whether inflammatory biomarkers can improve dementia prediction models, such as the widely used Cardiovascular Risk Factors, Aging and Dementia (CAIDE) model.

METHODS

The Olink Target 96 Inflammation panel was assessed in a nested case-cohort design within a large, population-based German cohort study (n = 9940; age-range: 50-75 years). All study participants who developed dementia over 20 years of follow-up and had complete CAIDE variable data (n = 562, including 173 Alzheimer's disease (AD) and 199 vascular dementia (VD) cases) as well as n = 1,356 controls were selected for measurements. 69 inflammation-related biomarkers were eligible for use. LASSO logistic regression and bootstrapping were utilized to select relevant biomarkers and determine areas under the curve (AUCs).

RESULTS

The CAIDE model 2 (including Apolipoprotein E (APOE) ε4 carrier status) predicted all-cause dementia, AD, and VD better than CAIDE model 1 (without APOE ε4) with AUCs of 0.725, 0.752 and 0.707, respectively. Although 20, 7, and 4 inflammation-related biomarkers were selected by LASSO regression to improve CAIDE model 2, the AUCs did not increase markedly. CAIDE models 1 and 2 generally performed better in mid-life (50-64 years) than in late-life (65-75 years) sub-samples of our cohort, but again, inflammation-related biomarkers did not improve their predictive abilities.

CONCLUSIONS

Despite a lack of improvement in dementia risk prediction, the selected inflammation-related biomarkers were significantly associated with dementia outcomes and may serve as a starting point to further elucidate the pathogenesis of dementia.

Discovery of small molecule benzothiazole and indole derivatives tackling tau 2N4R and α-synuclein fibrils

Tau and α-synuclein aggregates are the main histopathological hallmarks present in Alzheimer's disease (AD), Parkinson's disease (PD), and other neurodegenerative disorders. Intraneuronal hyperphosphorylated tau accumulation is significantly connected to the degree of cognitive impairment in AD patients. In particular, the longest 2N4R tau isoform has a propensity to rapidly form oligomers and mature fibrils. On the other hand, misfolding of α-synuclein (α-syn) is the characteristic feature in PD and dementia with Lewy bodies (DLB). There is a strong crosstalk between the two prone-to-aggregation proteins as they coprecipitated in some brains of AD, PD, and DLB patients. Simultaneous targeting of both proteinaceous oligomers and aggregates is still challenging. Here, we rationally designed and synthesized benzothiazole- and indole-based compounds using the structural hybridization strategy between the benzothiazole N744 cyanine dye and the diphenyl pyrazole Anle138b that showed anti-aggregation activity towards 2N4R tau and α-syn, respectively. The anti-aggregation effect of the prepared compounds was monitored using the thioflavin-T (ThT) fluorescence assay, while transmission electron microscopy (TEM) was employed to detect fibrils upon the completion of a time-course study with the ThT assay. Moreover, the photo-induced crosslinking of unmodified protein (PICUP) assay was used to determine the formation of oligomers. Specifically, compounds 46 and 48 demonstrated the highest anti-aggregation activity by decreasing the ThT fluorescence to 4.0 and 14.8%, respectively, against α-syn. Although no noticeable effect on 2N4R tau oligomers, 46 showed promising anti-oligomer activity against α-syn. Both compounds induced a significantly high anti-aggregation effect against the two protein fibrils as visualized by TEM. Moreover, compound 48 remarkably inhibited α-syn inclusion and cell confluence using M17D cells. Collectively, compounds 46 and 48 could serve as a basic structure for further optimization to develop clinically active AD and PD disease-modifying agents.

Anti-amyloid antibody treatments for Alzheimer's disease

Our aim is to review the most recent evidence on novel antibody therapies for Alzheimer's disease directed against amyloid-β. This is a joint statement of the European Association of Neurology and the European Psychiatric Association. After numerous unsuccessful endeavors to create a disease-modifying therapy for Alzheimer's disease, substantial and consistent evidence supporting the clinical effectiveness of monoclonal antibodies aimed at amyloid-β is finally emerging. The latest trials not only achieved their primary objective of slowing the progression of the disease over several months but also demonstrated positive secondary clinical outcomes and a decrease in amyloid-β levels as observed through positron emission tomography scans. Taken as a whole, these findings mark a significant breakthrough by substantiating that reducing amyloid-β yields tangible clinical benefits, beyond mere changes in biomarkers. Concurrently, the regular utilization of the new generation of drugs will determine whether statistical efficacy translates into clinically meaningful improvements. This may well signify the dawning of a new era in the development of drugs for Alzheimer's disease.

Donepezil-Loaded Nanocarriers for the Treatment of Alzheimer's Disease: Superior Efficacy of Extracellular Vesicles Over Polymeric Nanoparticles

Introduction

Drug delivery across the blood-brain barrier (BBB) is challenging and therefore severely restricts neurodegenerative diseases therapy such as Alzheimer's disease (AD). Donepezil (DNZ) is an acetylcholinesterase (AChE) inhibitor largely prescribed to AD patients, but its use is limited due to peripheral adverse events. Nanodelivery strategies with the polymer Poly (lactic acid)-poly(ethylene glycol)-based nanoparticles (NPs-PLA-PEG) and the extracellular vesicles (EVs) were developed with the aim to improve the ability of DNZ to cross the BBB, its brain targeting and efficacy.

Methods

EVs were isolated from human plasma and PLA-PEG NPs were synthesized by nanoprecipitation. The toxicity, brain targeting capacity and cholinergic activities of the formulations were evaluated both in vitro and in vivo.

Results

EVs and NPs-PLA-PEG were designed to be similar in size and charge, efficiently encapsulated DNZ and allowed sustained drug release. In vitro study showed that both formulations EVs-DNZ and NPs-PLA-PEG-DNZ were highly internalized by the endothelial cells bEnd.3. These cells cultured on the Transwell® model were used to analyze the transcytosis of both formulations after validation of the presence of tight junctions, the transendothelial electrical resistance (TEER) values and the permeability of the Dextran-FITC. In vivo study showed that both formulations were not toxic to zebrafish larvae (Danio rerio). However, hyperactivity was evidenced in the NPs-PLA-PEG-DNZ and free DNZ groups but not the EVs-DNZ formulations. Biodistribution analysis in zebrafish larvae showed that EVs were present in the brain parenchyma, while NPs-PLA-PEG remained mainly in the bloodstream.

Conclusion

The EVs-DNZ formulation was more efficient to inhibit the AChE enzyme activity in the zebrafish larvae head. Thus, the bioinspired delivery system (EVs) is a promising alternative strategy for brain-targeted delivery by substantially improving the activity of DNZ for the treatment of AD.

Regional MRI volumetry using NeuroQuant versus visual rating scales in patients with cognitive impairment and dementia

BACKGROUND AND PURPOSE

The aims were to compare the novel regional brain volumetric measures derived by the automatic software NeuroQuant (NQ) with clinically used visual rating scales of medial temporal lobe atrophy (MTA), global cortical atrophy-frontal (GCA-f), and posterior atrophy (PA) brain regions, assessing their diagnostic validity, and to explore if combining automatic and visual methods would increase diagnostic prediction accuracy.

METHODS

Brain magnetic resonance imaging (MRI) examinations from 86 patients with subjective and mild cognitive impairment (i.e., non-dementia, n = 41) and dementia (n = 45) from the Memory Clinic at Oslo University Hospital were assessed using NQ volumetry and with visual rating scales. Correlations, receiver operating characteristic analyses calculating area under the curves (AUCs) for diagnostic accuracy, and logistic regression analyses were performed.

RESULTS

The correlations between NQ volumetrics and visual ratings of corresponding regions were generally high between NQ hippocampi/temporal volumes and MTA (r = -0.72/-0.65) and between NQ frontal volume and GCA-f (r = -0.62) but lower between NQ parietal/occipital volumes and PA (r = -0.49/-0.37). AUCs of each region, separating non-dementia from dementia, were generally comparable between the two methods, except that NQ hippocampi volume did substantially better than visual MTA (AUC = 0.80 vs. 0.69). Combining both MRI methods increased only the explained variance of the diagnostic prediction substantially regarding the posterior brain region.

CONCLUSIONS

The findings of this study encourage the use of regional automatic volumetry in locations lacking neuroradiologists with experience in the rating of atrophy typical of neurodegenerative diseases, and in primary care settings.

Polygalacic acid attenuates cognitive impairment by regulating inflammation through PPARγ/NF-κB signaling pathway

AIMS

We aimed to explore the role and molecular mechanism of polygalacic acid (PA) extracted from traditional Chinese medicine Polygala tenuifolia in the treatment of Alzheimer's disease (AD).

METHODS

The network pharmacology analysis was used to predict the potential targets and pathways of PA. Molecular docking was applied to analyze the combination between PA and core targets. Aβ42 oligomer-induced AD mice model and microglia were used to detect the effect of PA on the release of pro-inflammatory mediators and its further mechanism. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of PA on activating microglia-mediated neuronal apoptosis.

RESULTS

We predict that PA might regulate inflammation by targeting PPARγ-mediated pathways by using network pharmacology. In vivo study, PA could attenuate cognitive deficits and inhibit the expression levels of inflammation-related factors. In vitro study, PA can also decrease the production of activated microglia-mediated inflammatory cytokines and reduce the apoptosis of N2a neuronal cells. PPARγ inhibitor GW9662 inversed the neuroprotective effect of PA. Both in vivo and in vitro studies showed PA might attenuate the inflammation through the PPARγ/NF-κB pathway.

CONCLUSIONS

PA is expected to provide a valuable candidate for new drug development for AD in the future.

Clearance of extracellular human amyloid-β aggregates in C. elegans by nutraceutical and pharmaceutical interventions

Numerous anti-amyloid therapies have seen recent clinical development and approval, such as the monoclonal antibodies aducanumab and lecanemab. However, in Alzheimer's disease patients, amyloid-β (Aβ) plaques are found embedded in the extracellular matrix and surrounded by collagens, which might hinder these antibodies from targeting the plaques. We reasoned that various different nutraceutical and pharmaceutical agents might induce collagen and extracellular matrix turnover and removal of these collagen-embedded amyloid-β (Aβ) plaques. To address this idea, here, we used a transgenic C. elegans strain, LSD2104 , expressing fluorescent human Aβ 1-42 as an in-vivo model for secreted amyloid aggregation in the extracellular matrix. We performed a screen of various nutraceuticals and pharmaceuticals along with different combinations, and we found that quercetin 350 µM and rifampicin 75 µM successfully cleared the extracellular amyloid plaque burden compared to the 0.2% DMSO control group, with a combination of the two agents producing the maximum effect compared to either drug alone. These results may implicate the exploration of combination therapeutics of nutraceuticals and pharmaceuticals in the clearance of amyloid-β (Aβ) plaques in Alzheimer's disease.

Radiotherapy for non-cancer diseases: benefits and long-term risks

PURPOSE

The discovery of X-rays was followed by a variety of attempts to treat infectious diseases and various other non-cancer diseases with ionizing radiation, in addition to cancer. There has been a recent resurgence of interest in the use of such radiotherapy for non-cancer diseases. Non-cancer diseases for which use of radiotherapy has currently been proposed include refractory ventricular tachycardia, neurodegenerative diseases (e.g. Alzheimer's disease and dementia), and Coronavirus Disease 2019 (COVID-19) pneumonia, all with ongoing clinical studies that deliver radiation doses of 0.5-25 Gy in a single fraction or in multiple daily fractions. In addition to such non-cancer effects, historical indications predominantly used in some countries (e.g. Germany) include osteoarthritis and degenerative diseases of the bones and joints. This narrative review gives an overview of the biological rationale and ongoing preclinical and clinical studies for radiotherapy proposed for various non-cancer diseases, discusses the plausibility of the proposed biological rationale, and considers the long-term radiation risks of cancer and non-cancer diseases.

CONCLUSIONS

A growing body of evidence has suggested that radiation represents a double-edged sword, not only for cancer, but also for non-cancer diseases. At present, clinical evidence has shown some beneficial effects of radiotherapy for ventricular tachycardia, but there is little or no such evidence of radiotherapy for other newly proposed non-cancer diseases (e.g. Alzheimer's disease, COVID-19 pneumonia). Patients with ventricular tachycardia and COVID-19 pneumonia have thus far been treated with radiotherapy when they are an urgent life threat with no efficient alternative treatment, but some survivors may encounter a paradoxical situation where patients were rescued by radiotherapy but then get harmed by radiotherapy. Further studies are needed to justify the clinical use of radiotherapy for non-cancer diseases, and optimize dose to diseased tissue while minimizing dose to healthy tissue.

Bayesian meta-analysis of phase 3 results of aducanumab, lecanemab, donanemab, and high-dose gantenerumab in prodromal and mild Alzheimer's disease

INTRODUCTION

Phase 3 trials using the anti-amyloid antibodies aducanumab, lecanemab, donanemab, and high-dose gantenerumab in prodromal and mild Alzheimer's disease dementia were heterogeneous in respect to statistical significance of effects. However, heterogeneity of results has not yet directly be quantified.

METHODS

We used Bayesian random effects meta-analysis to quantify evidence for or against a treatment effect, and assessed the size of the effect and its heterogeneity. Data were extracted from published studies where available and Web based data reports, assuming a Gaussian data generation process.

RESULTS

We found moderate evidence in favor of a treatment effect (Bayes factor = 13.2). The effect was moderate to small with -0.33 (95% credible interval -0.54 to -0.10) points on the Clinical Dementia Rating - Sum of Boxes (CDR-SB) scale. The heterogeneity parameter was low to moderate with 0.21 (0.04 to 0.45) CDR-SB points.

DISCUSSION

Heterogeneity across studies was moderate despite some trials reaching statistical significance, while others did not. This suggests that the negative aducanumab and gantenerumab trials are in full agreement with the expected effect sizes.

Anti-Amyloid Monoclonal Antibodies for the Treatment of Alzheimer's Disease

Two monoclonal antibodies (mAbs), aducanumab and lecanemab, have received accelerated approval from the US FDA for initiation of treatment in early Alzheimer's disease patients who have proven β-amyloid pathology (Aβ). One of these, lecanemab, has subsequently received full approval and other monoclonal antibodies are poised for positive review and approval. Anti-amyloid mAbs share the feature of producing a marked reduction in total brain Aβ revealed by amyloid positron emission tomography. Trials associated with slowing of cognitive decline have achieved a reduction in measurable plaque Aβ in the range of 15-25 centiloids; trials of agents that did not reach this threshold were not associated with cognitive benefit. mAbs have differences in terms of titration schedules, MRI monitoring schedules for amyloid-related imaging abnormalities (ARIA), and continuing versus interrupted therapy. The approximate 30% slowing of decline observed with mAbs is clinically meaningful in terms of extended cognitive integrity and delay of onset of the more severe dementia phases of Alzheimer's disease. Approval of these agents initiates a new era in Alzheimer's disease therapeutics with disease-modifying properties. Further advances are needed, i.e. greater efficacy, improved safety, enhanced convenience, and better understanding of ill-understood observations such as brain volume loss.

Blood-Based Biomarkers for Early Alzheimer's Disease Diagnosis in Real-World Settings

As our knowledge about the biology of Alzheimer's disease (AD) expands and we recognize the significance of early intervention for effective treatment, there is a shift in focus toward detecting the disease at an early stage. AD is characterized by the accumulation of misfolded amyloid-β (Aβ) and phosphorylated tau proteins in the brain, leading to the formation of senile plaques and neurofibrillary tangles. While a definitive diagnosis of AD can only be confirmed through autopsy by examining these pathological features, there are now reliable methods available for diagnosing the disease in living individuals. These methods involve analyzing cerebrospinal fluid and using positron emission tomography to accurately assess the presence of Aβ and tau proteins. While these diagnostic markers have shown high accuracy in memory-clinic populations, they do have limitations such as the requirement for invasive lumbar puncture or exposure to ionizing radiation. Additionally, they are not easily accessible outside of specialized healthcare settings. Blood-based biomarkers of the core pathological features of AD are being developed, showing promise for less invasive, scalable identification of AD cases in the community. The advantages for the healthcare systems of this development are obvious, but the diagnostic performance of blood-based biomarkers in broader, non-selected populations outside of retrospective analyses and research cohorts still requires further investigation, including the combination with more effective neuropsychological assessments such as digital cognitive test solutions.

Alzheimer's Disease Prevention and Treatment Based on Population-Based Approaches

The development of effective prevention and treatment strategies for Alzheimer's disease (AD) and dementia is hindered by limited knowledge of the underlying biological and environmental causes. While certain genetic factors have been associated with AD, and various lifestyle and environmental factors have been linked to dementia risk, the interactions between genes and the environment are not yet fully understood. To identify new avenues for dementia prevention, coordinated global efforts are needed to utilize existing cohorts and resources effectively and efficiently. This chapter provides an overview of current research on risk and protective factors for AD and dementia and discusses the opportunities and challenges associated with population-based approaches.

Once upon a time, the Amyloid Cascade Hypothesis

Recent trials with monoclonal antibodies targeting amyloid-β (Aβ) in Alzheimer's disease (AD) have sparked a renewed interest in disease-modifying therapies. Despite their promise, these trials leave the issue open and posit some doubts about the validity of the Amyloid Cascade Hypothesis (ACH). While some scores of neurocognitive tests improved upon treatment, real-world clinical benefits were minimal. This Viewpoint discusses additional, often overlooked findings from these trials. We also emphasize the multifactorial nature of AD and the need for a broader research perspective beyond the simplistic disease model provided by the ACH.

Finding the best location: Improving the anti-amyloid ability of ruthenium(III) complexes with pyridine ligands

Alzheimer's disease (AD) is a devastating neurological disorder where one of the primary pathological hallmarks are aggregate deposits of the peptide amyloid-beta (Aβ). Although the Food and Drug Administration (FDA) has recently approved therapeutics that specifically target Aβ, resulting in the removal of these deposits, the associated costs of such treatments create a need for effective, yet cheaper, alternatives. Metal-based compounds are propitious therapeutic candidates as they exploit the metal-binding properties of Aβ, forming stable interactions with the peptide, thereby limiting its aggregation and toxicity. Previously, ruthenium-based complexes have shown a strong ability to modulate the aggregation and cytotoxicity of Aβ, where the incorporation of a primary amine on the coordinated heterocyclic ligand gave the greatest activity. To determine the importance of the location of the primary amine on the pyridine ligand, thereby establishing structure-activity relationships (SAR), four complexes (RuP1-4) were prepared and evaluated for their ability to coordinate and subsequently modulate the aggregation and cytotoxicity of Aβ. Coordination to Aβ was determined using three complementary spectroscopic methods: UV-Vis, 1H NMR, and circular dichroism (CD). Similarly, the impact of the complexes on Aβ aggregation was evaluated using three sequential methods of turbidity, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Overall, the location of the primary amine on the pyridine ligand did affect the resultant anti-Aβ performance, with the 2-aminopyridine complex (RuP2) being the most active. This SAR will provide another guiding principle in the design of future metal-based anti-Aβ complexes.

Focusing on Earlier Management of Alzheimer Disease: Expert Opinion Based on a Modified Nominal Group Technique

BACKGROUND

Despite the number of people living with Alzheimer disease (AD), awareness of the early stages of this condition, including mild cognitive impairment due to AD-which poses management challenges-continues to be low. To identify areas for improvement in early AD management, dementia specialists convened in a virtual roundtable meeting.

METHODOLOGY

A modified version of the nominal group technique was followed to prioritize specific topics and allow experts to provide their opinions. The overarching topics prioritized and discussed were (1) education and support for primary care physicians on cognitive assessment, detection of mild cognitive impairment, and patient monitoring; (2) nonpharmacological interventions; (3) and the introduction of disease-modifying therapies.

CONCLUSIONS

Consensus was achieved regarding the need for educating primary care physicians on identifying people with cognitive impairment and for better diagnostic tools for its detection and early management. Management of mild cognitive impairment due to AD should encompass an adequate follow-up schedule aiming to maintain function for as long as possible, and primary care physicians and patients should be aware of the benefits of nonpharmacological interventions.

Passive Immunotherapies Targeting Amyloid-β in Alzheimer's Disease: A Quantitative Systems Pharmacology Perspective

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by amyloid-β (Aβ) protein accumulation in the brain. Passive immunotherapies using monoclonal antibodies for targeting Aβ have shown promise for AD treatment. Indeed, recent US Food and Drug Administration approval of aducanumab and lecanemab, alongside positive donanemab Phase III results demonstrated clinical efficacy after decades of failed clinical trials for AD. However, the pharmacological basis distinguishing clinically effective from ineffective therapies remains unclear, impeding development of potent therapeutics. This study aimed to provide a quantitative perspective for effectively targeting Aβ with antibodies. We first reviewed the contradicting results associated with the amyloid hypothesis and the pharmacological basis of Aβ immunotherapy. Subsequently, we developed a quantitative systems pharmacology (QSP) model that describes the non-linear progression of Aβ pathology and the pharmacologic actions of the Aβ-targeting antibodies. Using the QSP model, we analyzed various scenarios for effective passive immunotherapy for AD. The model revealed that binding exclusively to the Aβ monomer has minimal effect on Aβ aggregation and plaque reduction, making the antibody affinity toward Aβ monomer unwanted, as it could become a distractive mechanism for plaque reduction. Neither early intervention, high brain penetration, nor increased dose could yield significant improvement of clinical efficacy for antibodies targeting solely monomers. Antibodies that bind all Aβ species but lack effector function exhibited moderate effects in plaque reduction. Our model highlights the importance of binding aggregate Aβ species and incorporating effector functions for efficient and early plaque reduction, guiding the development of more effective therapies for this devastating disease. SIGNIFICANCE STATEMENT: Despite previous unsuccessful attempts spanning several decades, passive immunotherapies utilizing monoclonal antibodies for targeting amyloid-beta (Aβ) have demonstrated promise with two recent FDA approvals. However, the pharmacological basis that differentiates clinically effective therapies from ineffective ones remains elusive. Our study offers a quantitative systems pharmacology perspective, emphasizing the significance of selectively targeting specific Aβ species and importance of antibody effector functions. This perspective sheds light on the development of more effective therapies for this devastating disease.

Brain Age Estimation on a Dementia Cohort Using FLAIR MRI Biomarkers

BACKGROUND AND PURPOSE

The prodromal stage of Alzheimer's disease presents an imperative intervention window. This work focuses on using brain age prediction models and biomarkers from FLAIR MR imaging to identify subjects who progress to Alzheimer's disease (converting mild cognitive impairment) or those who remain stable (stable mild cognitive impairment).

MATERIALS AND METHODS

A machine learning model was trained to predict the age of normal control subjects on the basis of volume, intensity, and texture features from 3239 FLAIR MRI volumes. The brain age gap estimation (BrainAGE) was computed as the difference between the predicted and true age, and it was used as a biomarker for both cross-sectional and longitudinal analyses. Differences in biomarker means, slopes, and intercepts were investigated using ANOVA and Tukey post hoc test. Correlation analysis was performed between brain age gap estimation and established Alzheimer's disease indicators.

RESULTS

The brain age prediction model showed accurate results (mean absolute error = 2.46 years) when testing on held out normal control data. The computed BrainAGE metric showed significant differences between the stable mild cognitive impairment and converting mild cognitive impairment groups in cross-sectional and longitudinal analyses, most notably showing significant differences up to 4 years before conversion to Alzheimer's disease. A significant correlation was found between BrainAGE and previously established Alzheimer's disease conversion biomarkers.

CONCLUSIONS

The BrainAGE metric can allow clinicians to consider a single explainable value that summarizes all the biomarkers because it considers many dimensions of disease and can determine whether the subject has normal aging patterns or if he or she is trending into a high-risk category using a single value.

An inclusive study of recent advancements in Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) has remained elusive in revealing its pathophysiology and mechanism of development. In this review paper, we attempt to highlight several theories that abound about the exact pathway of AD development. The number of cases worldwide has prompted a constant flow of research to detect high-risk patients, slow the progression of the disease and discover improved methods of treatment that may prove effective. We shall focus on the two main classes of drugs that are currently in use; and emerging ones with novel mechanisms that are under development. As of late there has also been increased attention towards factors that were previously thought to be unrelated to AD, such as the gut microbiome, lifestyle habits, and diet. Studies have now shown that all these factors make an impact on AD progression, thus bringing to our attention more areas that could hold the key to combating this disease. This paper covers all the aforementioned factors concisely. We also briefly explore the relationship between mental health and AD, both before and after the diagnosis of the disease.

Molecular modeling of apoE in complexes with Alzheimer's amyloid-β fibrils from human brain suggests a structural basis for apolipoprotein co-deposition with amyloids

Apolipoproteins co-deposit with amyloids, yet apolipoprotein-amyloid interactions are enigmatic. To understand how apoE interacts with Alzheimer's amyloid-β (Aβ) peptide in fibrillary deposits, the NMR structure of full-length human apoE was docked to four structures of patient-derived Aβ1-40 and Aβ1-42 fibrils determined previously using cryo-electron microscopy or solid-state NMR. Similar docking was done using the NMR structure of human apoC-III. In all complexes, conformational changes in apolipoproteins were required to expose large hydrophobic faces of their amphipathic α-helices for sub-stoichiometric binding to hydrophobic surfaces on sides or ends of fibrils. Basic residues flanking the hydrophobic helical faces in apolipoproteins interacted favorably with acidic residue ladders in some amyloid polymorphs. Molecular dynamics simulations of selected apoE-fibril complexes confirmed their stability. Amyloid binding via cryptic sites, which became available upon opening of flexibly linked apolipoprotein α-helices, resembled apolipoprotein-lipid binding. This mechanism probably extends to other apolipoprotein-amyloid interactions. Apolipoprotein binding alongside fibrils could interfere with fibril fragmentation and secondary nucleation, while binding at the fibril ends could halt amyloid elongation and dissolution in a polymorph-specific manner. The proposed mechanism is supported by extensive prior experimental evidence and helps reconcile disparate reports on apoE's role in Aβ aggregation. Furthermore, apoE domain opening and direct interaction of Arg/Cys158 with amyloid potentially contributes to isoform-specific effects in Alzheimer's disease. In summary, current modeling supported by prior experimental studies suggests similar mechanisms for apolipoprotein-amyloid and apolipoprotein-lipid interactions; explains why apolipoproteins co-deposit with amyloids; and helps reconcile conflicting reports on the chaperone-like apoE action in Aβ aggregation.

Alzheimer's disease: The role of proteins in formation, mechanisms, and new therapeutic approaches

Alzheimer's disease (AD) is a progressive neurological disorder that affects the central nervous system (CNS), leading to memory and cognitive decline. In AD, the brain experiences three main structural changes: a significant decrease in the quantity of neurons, the development of neurofibrillary tangles (NFT) composed of hyperphosphorylated tau protein, and the formation of amyloid beta (Aβ) or senile plaques, which are protein deposits found outside cells and surrounded by dystrophic neurites. Genetic studies have identified four genes associated with autosomal dominant or familial early-onset AD (FAD): amyloid precursor protein (APP), presenilin 1 (PS1), presenilin 2 (PS2), and apolipoprotein E (ApoE). The formation of plaques primarily involves the accumulation of Aβ, which can be influenced by mutations in APP, PS1, PS2, or ApoE genes. Mutations in the APP and presenilin (PS) proteins can cause an increased amyloid β peptides production, especially the further form of amyloidogenic known as Aβ42. Apart from genetic factors, environmental factors such as cytokines and neurotoxins may also have a significant impact on the development and progression of AD by influencing the formation of amyloid plaques and intracellular tangles. Exploring the causes and implications of protein aggregation in the brain could lead to innovative therapeutic approaches. Some promising therapy strategies that have reached the clinical stage include using acetylcholinesterase inhibitors, estrogen, nonsteroidal anti-inflammatory drugs (NSAIDs), antioxidants, and antiapoptotic agents. The most hopeful therapeutic strategies involve inhibiting activity of secretase and preventing the β-amyloid oligomers and fibrils formation, which are associated with the β-amyloid fibrils accumulation in AD. Additionally, immunotherapy development holds promise as a progressive therapeutic approach for treatment of AD. Recently, the two primary categories of brain stimulation techniques that have been studied for the treatment of AD are invasive brain stimulation (IBS) and non-invasive brain stimulation (NIBS). In this article, the amyloid proteins that play a significant role in the AD formation, the mechanism of disease formation as well as new drugs utilized to treat of AD will be reviewed.

Amyloid β-Oligomers Inhibit the Nuclear Ca2+ Signals and the Neuroprotective Gene Expression Induced by Gabazine in Hippocampal Neurons

Hippocampal neuronal activity generates dendritic and somatic Ca2+ signals, which, depending on stimulus intensity, rapidly propagate to the nucleus and induce the expression of transcription factors and genes with crucial roles in cognitive functions. Soluble amyloid-beta oligomers (AβOs), the main synaptotoxins engaged in the pathogenesis of Alzheimer's disease, generate aberrant Ca2+ signals in primary hippocampal neurons, increase their oxidative tone and disrupt structural plasticity. Here, we explored the effects of sub-lethal AβOs concentrations on activity-generated nuclear Ca2+ signals and on the Ca2+-dependent expression of neuroprotective genes. To induce neuronal activity, neuron-enriched primary hippocampal cultures were treated with the GABAA receptor blocker gabazine (GBZ), and nuclear Ca2+ signals were measured in AβOs-treated or control neurons transfected with a genetically encoded nuclear Ca2+ sensor. Incubation (6 h) with AβOs significantly reduced the nuclear Ca2+ signals and the enhanced phosphorylation of cyclic AMP response element-binding protein (CREB) induced by GBZ. Likewise, incubation (6 h) with AβOs significantly reduced the GBZ-induced increases in the mRNA levels of neuronal Per-Arnt-Sim domain protein 4 (Npas4), brain-derived neurotrophic factor (BDNF), ryanodine receptor type-2 (RyR2), and the antioxidant enzyme NADPH-quinone oxidoreductase (Nqo1). Based on these findings we propose that AβOs, by inhibiting the generation of activity-induced nuclear Ca2+ signals, disrupt key neuroprotective gene expression pathways required for hippocampal-dependent learning and memory processes.

Site-oriented conjugation of poly(2-methacryloyloxyethyl phosphorylcholine) for enhanced brain delivery of antibody

Antibody therapeutics are limited in treating brain diseases due to poor blood-brain barrier (BBB) penetration. We have discovered that poly 2-methacryloyloxyethyl phosphorylcholine (PMPC), a biocompatible polymer, effectively facilitates BBB penetration via receptor-mediated transcytosis and have developed a PMPC-shell-based platform for brain delivery of therapeutic antibodies, termed nanocapsule. Yet, the platform results in functional loss of antibodies due to epitope masking by the PMPC polymer network, which necessitates the incorporation of a targeting moiety and degradable crosslinker to enable on-site antibody release. In this study, we developed a novel platform based on site-oriented conjugation of PMPC to the antibody, allowing it to maintain key functionalities of the original antibody. With an optimized PMPC chain length, the PMPC-antibody conjugate exhibited enhanced brain delivery while retaining epitope recognition, cellular internalization, and antibody-dependent cellular phagocytic activity. This simple formula incorporates only the antibody and PMPC without requiring additional components, thereby addressing the issues of the nanocapsule platform and paving the way for PMPC-based brain delivery strategies for antibodies.

Impact of Microbiome-Brain Communication on Neuroinflammation and Neurodegeneration

The gut microbiome plays a pivotal role in maintaining human health, with numerous studies demonstrating that alterations in microbial compositions can significantly affect the development and progression of various immune-mediated diseases affecting both the digestive tract and the central nervous system (CNS). This complex interplay between the microbiota, the gut, and the CNS is referred to as the gut-brain axis. The role of the gut microbiota in the pathogenesis of neurodegenerative diseases has gained increasing attention in recent years, and evidence suggests that gut dysbiosis may contribute to disease development and progression. Clinical studies have shown alterations in the composition of the gut microbiota in multiple sclerosis patients, with a decrease in beneficial bacteria and an increase in pro-inflammatory bacteria. Furthermore, changes within the microbial community have been linked to the pathogenesis of Parkinson's disease and Alzheimer's disease. Microbiota-gut-brain communication can impact neurodegenerative diseases through various mechanisms, including the regulation of immune function, the production of microbial metabolites, as well as modulation of host-derived soluble factors. This review describes the current literature on the gut-brain axis and highlights novel communication systems that allow cross-talk between the gut microbiota and the host that might influence the pathogenesis of neuroinflammation and neurodegeneration.

The association of microbial infection and adaptive immune cell activation in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. Early symptoms include the loss of memory and mild cognitive ability; however, as the disease progresses, these symptoms can present with increased severity manifesting as mood and behaviour changes, disorientation, and a loss of motor/body control. AD is one of the leading causes of death in the UK, and with an ever-increasing ageing society, patient numbers are predicted to rise posing a significant global health emergency. AD is a complex neurophysiological disorder where pathology is characterized by the deposition and aggregation of misfolded amyloid-beta (Aβ)-protein that in-turn promotes excessive tau-protein production which together drives neuronal cell dysfunction, neuroinflammation, and neurodegeneration. It is widely accepted that AD is driven by a combination of both genetic and immunological processes with recent data suggesting that adaptive immune cell activity within the parenchyma occurs throughout disease. The mechanisms behind these observations remain unclear but suggest that manipulating the adaptive immune response during AD may be an effective therapeutic strategy. Using immunotherapy for AD treatment is not a new concept as the only two approved treatments for AD use antibody-based approaches to target Aβ. However, these have been shown to only temporarily ease symptoms or slow progression highlighting the urgent need for newer treatments. This review discusses the role of the adaptive immune system during AD, how microbial infections may be contributing to inflammatory immune activity and suggests how adaptive immune processes can pose as therapeutic targets for this devastating disease.

Altered ubiquitin signaling induces Alzheimer's disease-like hallmarks in a three-dimensional human neural cell culture model

Alzheimer's disease (AD) is characterized by toxic protein accumulation in the brain. Ubiquitination is essential for protein clearance in cells, making altered ubiquitin signaling crucial in AD development. A defective variant, ubiquitin B + 1 (UBB+1), created by a non-hereditary RNA frameshift mutation, is found in all AD patient brains post-mortem. We now detect UBB+1 in human brains during early AD stages. Our study employs a 3D neural culture platform derived from human neural progenitors, demonstrating that UBB+1 alone induces extracellular amyloid-β (Aβ) deposits and insoluble hyperphosphorylated tau aggregates. UBB+1 competes with ubiquitin for binding to the deubiquitinating enzyme UCHL1, leading to elevated levels of amyloid precursor protein (APP), secreted Aβ peptides, and Aβ build-up. Crucially, silencing UBB+1 expression impedes the emergence of AD hallmarks in this model system. Our findings highlight the significance of ubiquitin signalling as a variable contributing to AD pathology and present a nonclinical platform for testing potential therapeutics.

Production and N-glycan engineering of Varlilumab in Nicotiana benthamiana

N-glycan engineering has dramatically evolved for the development and quality control of recombinant antibodies. Fc region of IgG contains two N-glycans whose galactose terminals on Fc-glycan have been shown to increase the stability of CH2 domain and improve effector functions. Nicotiana benthamiana has become one of the most attractive production systems for therapeutic antibodies. In this study, Varlilumab, a CD27-targeting monoclonal antibody, was transiently produced in fresh leaves of soil-grown and hydroponic-grown N. benthamiana, resulted in the yield of 174 and 618 µg/gram, respectively. However, the IgG produced in wild-type N. benthamiana lacked the terminal galactose residues in its N-glycan. Therefore, N-glycan engineering was applied to fine-tune recombinant antibodies produced in plant platforms. We further co-expressed IgG together with murine β1,4-galactosyltransferase (β1,4-GALT) to modify plant N-glycan with β1,4-linked Gal residue(s) and Arabidopsis thaliana β1,3-galactosylatransferase (β1,3-GALT) to improve galactosylation. The co-expression of IgG with each of GALTs successfully resulted in modification of N-glycan structures on the plant-produced IgG. Notably, IgG co-expressed with murine β1,4-GALT in soil-grown N. benthamiana had 42.5% of N-glycans variants having galactose (Gal) residues at the non-reducing terminus and 55.3% of that in hydroponic-grown N. benthamiana plants. Concomitantly, N-glycan profile analysis of IgG co-expressed with β1,3-GALT demonstrated that there was an increased efficiency of galactosylation and an enhancement in the formation of Lewis a structure in plant-derived antibodies. Taken together, our findings show that the first plant-derived Varlilumab was successfully produced with biantennary β1,4-galactosylated N-glycan structures.

Molecular modeling of apoE in complexes with Alzheimer's amyloid-β fibrils from human brain suggests a structural basis for apolipoprotein co-deposition with amyloids

Apolipoproteins co-deposit with amyloids, yet apolipoprotein-amyloid interactions are enigmatic. To understand how apoE interacts with Alzheimer's amyloid-β (Aβ) peptide in fibrillary deposits, the NMR structure of full-length human apoE was docked to four structures of patient-derived Aβ1-40 and Aβ1-42 fibrils determined previously using cryo-electron microscopy or solid-state NMR. Similar docking was done using the NMR structure of human apoC-III. In all complexes, conformational changes in apolipoproteins were required to expose large hydrophobic faces of their amphipathic α-helices for sub-stoichiometric binding to hydrophobic surfaces on sides or ends of fibrils. Basic residues flanking the hydrophobic helical faces in apolipoproteins interacted favorably with acidic residue ladders in some amyloid polymorphs. Molecular dynamics simulations of selected apoE-fibril complexes confirmed their stability. Amyloid binding via cryptic sites, which became available upon opening of flexibly linked apolipoprotein α-helices, resembled apolipoprotein-lipid binding. This mechanism probably extends to other apolipoprotein-amyloid interactions. Apolipoprotein binding alongside fibrils could interfere with fibril fragmentation and secondary nucleation, while binding at the fibril ends could halt amyloid elongation and dissolution in a polymorph-specific manner. The proposed mechanism is supported by extensive prior experimental evidence and helps reconcile disparate reports on apoE's role in Aβ aggregation. Furthermore, apoE domain opening and direct interaction of Arg/Cys158 with amyloid potentially contributes to isoform-specific effects in Alzheimer's disease. In summary, current modeling supported by prior experimental studies suggests similar mechanisms for apolipoprotein-amyloid and apolipoprotein-lipid interactions; explains why apolipoproteins co-deposit with amyloids; and helps reconcile conflicting reports on the chaperone-like apoE action in Aβ aggregation.

siRNA drug delivery across the blood-brain barrier in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with a few FDA-approved drugs that provide modest symptomatic benefits and only two FDA-approved disease-modifying treatments for AD. The advancements in understanding the causative genes and non-coding sequences at the molecular level of the pathophysiology of AD have resulted in several exciting research papers that employed small interfering RNA (siRNA)-based therapy. Although siRNA is being sought by academia and biopharma industries, several challenges still need to be addressed. We comprehensively report the latest advances in AD pathophysiology, druggable targets, ongoing clinical trials, and the siRNA-based approaches across the blood-brain barrier for addressing AD. This review describes the latest delivery systems employed to address this barrier. Critical insights and future perspectives on siRNA therapy for AD are also provided.

Central Nervous System Targeted Protein Degraders

Diseases of the central nervous system, which once occupied a large component of the pharmaceutical industry research and development portfolio, have for many years played a smaller part in major pharma pipelines-primarily due to the well cited challenges in target validation, valid translational models, and clinical trial design. Unfortunately, this decline in research and development interest has occurred in tandem with an increase in the medical need-in part driven by the success in treating other chronic diseases, which then results in a greater overall longevity along with a higher prevalence of diseases associated with ageing. The lead modality for drug agents targeting the brain remains the traditionally small molecule, despite potential in gene-based therapies and antibodies, particularly in the hugely anticipated anti-amyloid field, clearly driven by the additional challenge of effective distribution to the relevant brain compartments. However, in recognition of the growing disease burden, advanced therapies are being developed in tandem with improved delivery options. Hence, methodologies which were initially restricted to systemic indications are now being actively explored for a range of CNS diseases-an important class of which include the protein degradation technologies.

Real-Time Assessment of the Size Changes of Individual Sub-Visible Protein Particles under Buffer Variations: A Microfluidic Study

Protein particles in biological drugs can significantly impact drug efficacy and carry the risk of adverse effects. Despite advancements, the understanding and control of particle formation in biopharmaceutical manufacturing remain incomplete. Therefore, further investigation into protein particles is warranted, especially considering that novel formats of biological drugs may be more susceptible to aggregation and particle formation than conventional monoclonal antibodies. In this study, we introduce a microfluidic approach for the real-time analysis of individual sub-visible protein particles during buffer exchange. We find that the modulation of intermolecular forces, achieved by changing the buffer pH or urea concentration, leads to the reversible swelling and shrinkage of particles by up to 50%, which is a consequence of altered intermolecular distances. Additionally, we identify a discrepancy in the biophysical behavior of protein particles compared to monomeric protein. This finding highlights the limited predictive power of commonly applied biophysical characterization methods for particle formation in early formulation development. Moreover, the observed particle swelling may be associated with manufacturing deviations, such as filter clogging. These results highlight the importance of studying individual particles to gain a comprehensive insight into particle behavior and the impact of formulation variations in the biopharmaceutical industry.

Unraveling Lifelong Brain Morphometric Dynamics: A Protocol for Systematic Review and Meta-Analysis in Healthy Neurodevelopment and Ageing

A high incidence and prevalence of neurodegenerative diseases and neurodevelopmental disorders justify the necessity of well-defined criteria for diagnosing these pathologies from brain imaging findings. No easy-to-apply quantitative markers of abnormal brain development and ageing are available. We aim to find the characteristic features of non-pathological development and degeneration in distinct brain structures and to work out a precise descriptive model of brain morphometry in age groups. We will use four biomedical databases to acquire original peer-reviewed publications on brain structural changes occurring throughout the human life-span. Selected publications will be uploaded to Covidence systematic review software for automatic deduplication and blinded screening. Afterwards, we will manually review the titles, abstracts, and full texts to identify the papers matching eligibility criteria. The relevant data will be extracted to a 'Summary of findings' table. This will allow us to calculate the annual rate of change in the volume or thickness of brain structures and to model the lifelong dynamics in the morphometry data. Finally, we will adjust the loss of weight/thickness in specific brain areas to the total intracranial volume. The systematic review will synthesise knowledge on structural brain change across the life-span.

Molecular Mechanism of Zinc-Dependent Oligomerization of Alzheimer's Amyloid-β with Taiwan (D7H) Mutation

Amyloid-β (Aβ) is a peptide formed by 39-43 amino acids, heterogenous by the length of its C-terminus. Aβ constitutes a subnanomolar monomeric component of human biological fluids; however, in sporadic variants of Alzheimer's disease (AD), it forms soluble neurotoxic oligomers and accumulates as insoluble extracellular polymeric aggregates (amyloid plaques) in the brain tissues. The plaque formation is controlled by zinc ions; therefore, abnormal interactions between the ions and Aβ seem to take part in the triggering of sporadic AD. The amyloid plaques contain various Aβ isoforms, among which the most common is Aβ with an isoaspartate in position 7 (isoD7). The spontaneous conversion of D7 to isoD7 is associated with Aβ aging. Aβ molecules with isoD7 (isoD7-Aβ) easily undergo zinc-dependent oligomerization, and upon administration to transgenic animals (mice, nematodes) used for AD modeling, act as zinc-dependent seeds of the pathological aggregation of Aβ. The formation of zinc-bound homo- and hetero-oligomers with the participation of isoD7-Aβ is based on the rigidly structured segment 11-EVHH-14, located in the Aβ metal binding domain (Aβ₁₆). Some hereditary variants of AD are associated with familial mutations within the domain. Among these, the most susceptible to zinc-dependent oligomerization is Aβ with Taiwan (D7H) mutation (D7H-Aβ). In this study, the D7H-Aβ metal binding domain (D7H-Aβ₁₆) has been used as a model to establish the molecular mechanism of zinc-induced D7H-Aβ oligomerization through turbidimetry, dynamic light scattering, isothermal titration calorimetry, mass spectrometry, and computer modelling. Additionally, the modeling data showed that a molecule of D7H-Aβ, as well as isoD7-Aβ in combination with two Aβ molecules, renders a stable zinc-induced heterotrimer. The trimers are held together by intermolecular interfaces via zinc ions, with the primary interfaces formed by 11-EVHH-14 sites of the interacting trimer subunits. In summary, the obtained results confirm the role of the 11-EVHH-14 region as a structure and function determinant for the zinc-dependent oligomerization of all known Aβ species (including various chemically modified isoforms and AD-associated mutants) and point at this region as a potent target for drugs aimed to stop amyloid plaque formation in both sporadic and hereditary variants of AD.

Alzheimer's Disease: Treatment Today and Tomorrow

Background and Aims

The scope of treatment in Alzheimer's Disease has widened in recent times with FDA approval of new drugs. This review looks at established treatments in AD as well as critically analyses the newer drugs available.

Methods

Data in this review was gathered from PubMed; Google Scholar and MEDLINE from January-March 2023. Search words used were 'Alzheimer's Disease treatment' and 'Dementia treatment'.

Results

Older time tested drugs like Acetyl Choline Receptor Inhibitors and NMDA Receptor antagonists remain the mainstay of pharmacological treatment in AD. Despite a lot of excitement about newer FDA approved drugs; we have to be cautious in their use. Aducanumab showed good reduction in CSF amyloid levels (biomarker of AD); but this did not necessarily translate into better clinical outcomes of patients.

Conclusion

Despite the recent advances and approval of drugs in treatment of AD, we have to exhibit caution while prescribing these drugs. Even with a sound mechanism of action, these drugs do not always show improvement in clinical outcomes. More clinical trials are required for development of drugs in treatment of AD which explore various different mechanisms of action.

Restoration of metal homeostasis: a potential strategy against neurodegenerative diseases

Metal homeostasis is critical to normal neurophysiological activity. Metal ions are involved in the development, metabolism, redox and neurotransmitter transmission of the central nervous system (CNS). Thus, disturbance of homeostasis (such as metal deficiency or excess) can result in serious consequences, including neurooxidative stress, excitotoxicity, neuroinflammation, and nerve cell death. The uptake, transport and metabolism of metal ions are highly regulated by ion channels. There is growing evidence that metal ion disorders and/or the dysfunction of ion channels contribute to the progression of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Therefore, metal homeostasis-related signaling pathways are emerging as promising therapeutic targets for diverse neurological diseases. This review summarizes recent advances in the studies regarding the physiological and pathophysiological functions of metal ions and their channels, as well as their role in neurodegenerative diseases. In addition, currently available metal ion modulators and in vivo quantitative metal ion imaging methods are also discussed. Current work provides certain recommendations based on literatures and in-depth reflections to improve neurodegenerative diseases. Future studies should turn to crosstalk and interactions between different metal ions and their channels. Concomitant pharmacological interventions for two or more metal signaling pathways may offer clinical advantages in treating the neurodegenerative diseases.

Aβ-oligomers: A potential therapeutic target for Alzheimer's disease

The cascade of amyloid formation relates to multiple complex events at the molecular level. Previous research has established amyloid plaque deposition as the leading cause of Alzheimer's disease (AD) pathogenesis, detected mainly in aged population. The primary components of the plaques are two alloforms of amyloid-beta (Aβ), Aβ_1-42 and Aβ_1-40 peptides. Recent studies have provided considerable evidence contrary to the previous claim indicating that amyloid-beta oligomers (AβOs) as the main culprit responsible for AD-associated neurotoxicity and pathogenesis. In this review, we have discussed the primary features of AβOs, such as assembly formation, the kinetics of oligomer formation, interactions with various membranes/membrane receptors, the origin of toxicity, and oligomer-specific detection methods. Recently, the discovery of rationally designed antibodies has opened a gateway for using synthesized peptides as a grafting component in the complementarity determining region (CDR) of antibodies. Thus, the Aβ sequence motif or the complementary peptide sequence in the opposite strand of the β-sheet (extracted from the Protein Data Bank: PDB) helps design oligomer-specific inhibitors. The microscopic event responsible for oligomer formation can be targeted, and thus prevention of the overall macroscopic behaviour of the aggregation or the associated toxicity can be achieved. We have carefully reviewed the oligomer formation kinetics and associated parameters. Besides, we have depicted a thorough understanding of how the synthesized peptide inhibitors can impede the early aggregates (oligomers), mature fibrils, monomers, or a mixture of the species. The oligomer-specific inhibitors (peptides or peptide fragments) lack in-depth chemical kinetics and optimization control-based screening. In the present review, we have proposed a hypothesis for effectively screening oligomer-specific inhibitors using the chemical kinetics (determining the kinetic parameters) and optimization control strategy (cost-dependent analysis). Further, it may be possible to implement the structure-kinetic-activity-relationship (SKAR) strategy instead of structure-activity-relationship (SAR) to improve the inhibitor's activity. The controlled optimization of the kinetic parameters and dose usage will be beneficial for narrowing the search window for the inhibitors.

Intrathecal Pseudodelivery of Drugs in the Therapy of Neurodegenerative Diseases: Rationale, Basis and Potential Applications

Intrathecal pseudodelivery of drugs is a novel route to administer medications to treat neurodegenerative diseases based on the CSF-sink therapeutic strategy by means of implantable devices. While the development of this therapy is still in the preclinical stage, it offers promising advantages over traditional routes of drug delivery. In this paper, we describe the rationale of this system and provide a technical report on the mechanism of action, that relies on the use of nanoporous membranes enabling selective molecular permeability. On one side, the membranes do not permit the crossing of certain drugs; whereas, on the other side, they permit the crossing of target molecules present in the CSF. Target molecules, by binding drugs inside the system, are retained or cleaved and subsequently eliminated from the central nervous system. Finally, we provide a list of potential indications, the respective molecular targets, and the proposed therapeutic agents.

An Alternative View of Familial Alzheimer's Disease Genetics

Probabilistic and parsimony-based arguments regarding available genetics data are used to propose that Hardy and Higgin's amyloid cascade hypothesis is valid but is commonly interpreted too narrowly to support, incorrectly, the primacy of the amyloid-β peptide (Aβ) in driving Alzheimer's disease pathogenesis. Instead, increased activity of the βCTF (C99) fragment of AβPP is the critical pathogenic determinant altered by mutations in the APP gene. This model is consistent with the regulation of APP mRNA translation via its 5' iron responsive element. Similar arguments support that the pathological effects of familial Alzheimer's disease mutations in the genes PSEN1 and PSEN2 are not exerted directly via changes in AβPP cleavage to produce different ratios of Aβ length. Rather, these mutations likely act through effects on presenilin holoprotein conformation and function, and possibly the formation and stability of multimers of presenilin holoprotein and/or of the γ-secretase complex. All fAD mutations in APP, PSEN1, and PSEN2 likely find unity of pathological mechanism in their actions on endolysosomal acidification and mitochondrial function, with detrimental effects on iron homeostasis and promotion of "pseudo-hypoxia" being of central importance. Aβ production is enhanced and distorted by oxidative stress and accumulates due to decreased lysosomal function. It may act as a disease-associated molecular pattern enhancing oxidative stress-driven neuroinflammation during the cognitive phase of the disease.

Transcranial Direct Current Stimulation Intervention in Alzheimer's Disease and Its Follow-Up

BACKGROUND

Alzheimer's disease (AD) stands as the prevailing type of dementia, marked by gradual memory loss and cognitive decline. Transcranial direct current stimulation (tDCS) is a non-invasive method used to regulate cortical brain function and has been explored as a potential treatment for cognitive impairment.

OBJECTIVE

This study aimed to compare the effects of daily home-based active or sham tDCS on cognitive function in patients with early-stage AD and its follow-up after one month.

METHODS

The study involved a randomized, blinded, and controlled-placebo design, with 18 participants enrolled. The primary outcome measures were general cognitive function, immediate, and delayed recall, and executive function. Participants included in the study were randomly assigned to the anodal and sham tDCS groups. Participants were assessed before and after the intervention and one month after the end of treatment. The home-based intervention was applied for 5 consecutive days, daily.

RESULTS

The results showed a significant interaction between the active and sham groups; in particular, improvements in MMSE scores, immediate memory and delayed recall were observed at one-month follow-up in the active group.

CONCLUSIONS

The positive effects of tDCS on cognitive function in AD patients observed suggest that tDCS may induce long-term neuroplastic changes, leading to sustained improvements in cognitive abilities.