scholarly journals The Vagal Autonomic Pathway of COVID-19 at the Crossroad of Alzheimer’s Disease and Aging: A Review of Knowledge

2020 ◽  
Vol 4 (1) ◽  
pp. 537-551
Author(s):  
Claire-Marie Rangon ◽  
Slavica Krantic ◽  
Emmanuel Moyse ◽  
Bertrand Fougère
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Vagus Nerve ◽  
Large Scale ◽  
Low Cost ◽  
Non Invasive ◽  
Large Scale Testing ◽  
Cholinergic Pathway ◽  
Autonomic Pathway ◽  
Respiratory Rhythms

Coronavirus Disease 2019 (COVID-19) pandemic-triggered mortality is significantly higher in older than in younger populations worldwide. Alzheimer’s disease (AD) is related to aging and was recently reported to be among the major risk factors for COVID-19 mortality in older people. The symptomatology of COVID-19 indicates that lethal outcomes of infection rely on neurogenic mechanisms. The present review compiles the available knowledge pointing to the convergence of COVID-19 complications with the mechanisms of autonomic dysfunctions in AD and aging. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is prone to neuroinvasion from the lung along the vagus nerve up to the brainstem autonomic nervous centers involved in the coupling of cardiovascular and respiratory rhythms. The brainstem autonomic network allows SARS-CoV-2 to trigger a neurogenic switch to hypertension and hypoventilation, which may act in synergy with aging- and AD-induced dysautonomias, along with an inflammatory “storm”. The lethal outcomes of COVID-19, like in AD and unhealthy aging, likely rely on a critical hypoactivity of the efferent vagus nerve cholinergic pathway, which is involved in lowering cardiovascular pressure and systemic inflammation tone. We further discuss the emerging evidence supporting the use of 1) the non-invasive stimulation of vagus nerve as an additional therapeutic approach for severe COVID-19, and 2) the demonstrated vagal tone index, i.e., heart rate variability, via smartphone-based applications as a non-serological low-cost diagnostic of COVID-19. These two well-known medical approaches are already available and now deserve large-scale testing on human cohorts in the context of both AD and COVID-19.

IS A LARGE-SCALE SCREENING FOR ALZHEIMER’S DISEASE POSSIBLE? YES, IN A FEW YEARS

2019 ◽  
pp. 1-2
Author(s):  
F. Ribaldi ◽  
D. Altomare ◽  
G.B. Frisoni
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Large Scale ◽  
Task Force ◽  
Cost Effective ◽  
The European Union ◽  
New Era ◽  
Non Invasive ◽  
Recent Meeting ◽  
Large Scale Screening

Recent evidence on blood-based biomarkers is pointing the way towards a new era of large-scale, feasible, cost-effective and non-invasive screening for Alzheimer’s disease (AD). This was one of the main focuses of the recent meeting of the European Union-North American Clinical Trials in AD (EU/US CTAD) Task Force, which took place in Barcelona in October 24-27, 2018, and convened drug and diagnostics developers from industry and academia in order to define a roadmap for the development and marketing of blood-based biomarkers (1).

scholarly journals Biomarkers in Alzheimer’s disease

2021 ◽  
Author(s):  
Larissa Maria de Paula Rebouças da Costa ◽  
Gabriel de Souza Torres ◽  
Kauan Alves Sousa Madruga ◽  
Poliana Rafaela dos Santos
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Low Cost ◽  
Meta Analysis ◽  
Diagnostic Biomarkers ◽  
Non Invasive ◽  
Blood Tests ◽  
Pubmed Database ◽  
Amyloid Aβ ◽  
Phosphorylated Tau Protein

Background: Alzheimer’s disease (AD) is the most common cause of dementia and cognitive dysfunction in old ages. AD is characterised by beta- amyloid (Aβ) plaques and neurofibrillary tangles of the hyper-phosphorylated Tau protein. It has an extensive preclinical stage, which emphasizes the importance of the biological components related to an early diagnostic: biomarkers. Objectives: After critical analysis of the selected literature, this review has the goal of describing the main biomarkers in AD and discussing different ways of detecting it. Methods: This review was elaborated after a literature review in the PubMed database, with 15 articles published between 2016 and 2021. The keywords were used with the boolean operator “AND”. Articles of meta-analysis, review and systematic review were selected. Results: It was found central biomarkers for the AD diagnostic, such as Tau and Aβ. The following tests were used: CSF puncture; blood tests; neuroimaging; saliva and mucosa samples. Aβ and Tau can be collected by CSF or PET-TC. Conclusions: Biomarkers play an important role in early AD diagnostic, even with limitations in the tests. The CSF and PET-TC are expensive methods, only used in atypical cases of AD. Reliable blood tests remain in development. In conclusion, there’s the need for more studies about alternative diagnostic tests, that are non-invasive and have low cost. Those developments can be beneficial for health plans, helping early diagnosis of AD.

Dehydroepiandrosterone (DHEA) and its Sulphate (DHEAS) in Alzheimer’s Disease

2020 ◽  
Vol 17 (2) ◽  
pp. 141-157 ◽  
Author(s):  
Dubravka S. Strac ◽  
Marcela Konjevod ◽  
Matea N. Perkovic ◽  
Lucija Tudor ◽  
Gordana N. Erjavec ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Large Scale ◽  
Therapeutic Potential ◽  
Relevant Literature ◽  
Comprehensive Overview ◽  
Brain Functions ◽  
Specific Effects ◽  
And Behavior

Background: Neurosteroids Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone Sulphate (DHEAS) are involved in many important brain functions, including neuronal plasticity and survival, cognition and behavior, demonstrating preventive and therapeutic potential in different neuropsychiatric and neurodegenerative disorders, including Alzheimer’s disease. Objective: The aim of the article was to provide a comprehensive overview of the literature on the involvement of DHEA and DHEAS in Alzheimer’s disease. Method: PubMed and MEDLINE databases were searched for relevant literature. The articles were selected considering their titles and abstracts. In the selected full texts, lists of references were searched manually for additional articles. Results: We performed a systematic review of the studies investigating the role of DHEA and DHEAS in various in vitro and animal models, as well as in patients with Alzheimer’s disease, and provided a comprehensive discussion on their potential preventive and therapeutic applications. Conclusion: Despite mixed results, the findings of various preclinical studies are generally supportive of the involvement of DHEA and DHEAS in the pathophysiology of Alzheimer’s disease, showing some promise for potential benefits of these neurosteroids in the prevention and treatment. However, so far small clinical trials brought little evidence to support their therapy in AD. Therefore, large-scale human studies are needed to elucidate the specific effects of DHEA and DHEAS and their mechanisms of action, prior to their applications in clinical practice.

Structural Changes in Thalamic Nuclei Across Prodromal and Clinical Alzheimer’s Disease

2021 ◽  
pp. 1-11
Author(s):  
Adam S. Bernstein ◽  
Steven Z. Rapcsak ◽  
Michael Hornberger ◽  
Manojkumar Saranathan ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Large Scale ◽  
Structural Changes ◽  
Thalamic Nuclei ◽  
Medial Temporal Lobes ◽  
Cognitive Changes ◽  
Temporal Lobes ◽  
Medial Geniculate ◽  
Healthy Control

Background: Increasing evidence suggests that thalamic nuclei may atrophy in Alzheimer’s disease (AD). We hypothesized that there will be significant atrophy of limbic thalamic nuclei associated with declining memory and cognition across the AD continuum. Objective: The objective of this work was to characterize volume differences in thalamic nuclei in subjects with early and late mild cognitive impairment (MCI) as well as AD when compared to healthy control (HC) subjects using a novel MRI-based thalamic segmentation technique (THOMAS). Methods: MPRAGE data from the ADNI database were used in this study (n = 540). Healthy control (n = 125), early MCI (n = 212), late MCI (n = 114), and AD subjects (n = 89) were selected, and their MRI data were parcellated to determine the volumes of 11 thalamic nuclei for each subject. Volumes across the different clinical subgroups were compared using ANCOVA. Results: There were significant differences in thalamic nuclei volumes between HC, late MCI, and AD subjects. The anteroventral, mediodorsal, pulvinar, medial geniculate, and centromedian nuclei were significantly smaller in subjects with late MCI and AD when compared to HC subjects. Furthermore, the mediodorsal, pulvinar, and medial geniculate nuclei were significantly smaller in early MCI when compared to HC subjects. Conclusion: This work highlights nucleus specific atrophy within the thalamus in subjects with early and late MCI and AD. This is consistent with the hypothesis that memory and cognitive changes in AD are mediated by damage to a large-scale integrated neural network that extends beyond the medial temporal lobes.

scholarly journals Proteins and microRNAs are differentially expressed in tear fluid from patients with Alzheimer’s disease

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Aidan Kenny ◽  
Eva M. Jiménez-Mateos ◽  
María Ascensión Zea-Sevilla ◽  
Alberto Rábano ◽  
Pablo Gili-Manzanaro ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Unmet Need ◽  
Cost Effective ◽  
Specific Protein ◽  
Tear Fluid ◽  
Initiation Factor ◽  
Non Invasive ◽  
A Genome ◽  
Potential Biomarker

Abstract Alzheimer’s disease (AD) is characterized by a progressive loss of neurons and cognitive functions. Therefore, early diagnosis of AD is critical. The development of practical and non-invasive diagnostic tests for AD remains, however, an unmet need. In the present proof-of-concept study we investigated tear fluid as a novel source of disease-specific protein and microRNA-based biomarkers for AD development using samples from patients with mild cognitive impairment (MCI) and AD. Tear protein content was evaluated via liquid chromatography-mass spectrometry and microRNA content was profiled using a genome-wide high-throughput PCR-based platform. These complementary approaches identified enrichment of specific proteins and microRNAs in tear fluid of AD patients. In particular, we identified elongation initiation factor 4E (eIF4E) as a unique protein present only in AD samples. Total microRNA abundance was found to be higher in tears from AD patients. Among individual microRNAs, microRNA-200b-5p was identified as a potential biomarker for AD with elevated levels present in AD tear fluid samples compared to controls. Our study suggests that tears may be a useful novel source of biomarkers for AD and that the identification and verification of biomarkers within tears may allow for the development of a non-invasive and cost-effective diagnostic test for AD.

Micromolding Fabrication of Biocompatible Dry Micro-Pyramid Array Electrodes for Wearable Biopotential Monitoring

2021 ◽  
Author(s):  
Marco Vinicio Alban ◽  
Haechang Lee ◽  
Hanul Moon ◽  
Seunghyup Yoo
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Skin Irritation ◽  
Electrode Impedance ◽  
Non Invasive ◽  
Solution Processes ◽  
Dry Electrodes ◽  
Array Electrode ◽  
Low Cost Manufacturing ◽  
Electromyography Signals

Abstract Thin dry electrodes are promising components in wearable healthcare devices. Assessing the condition of the human body by monitoring biopotentials facilitates the early diagnosis of diseases as well as their prevention, treatment, and therapy. Existing clinical-use electrodes have limited wearable-device usage because they use gels, require preparation steps, and are uncomfortable to wear. While dry electrodes can improve these issues and have demonstrated performance on par with gel-based electrodes, providing advantages in mobile and wearable applications; the materials and fabrication methods used are not yet at the level of disposable gel electrodes for low-cost mass manufacturing and wide adoption. Here, a low-cost manufacturing process for thin dry electrodes with a conductive micro-pyramidal array is presented for large-scale on-skin wearable applications. The electrode is fabricated using micromolding techniques in conjunction with solution processes in order to guarantee ease of fabrication, high device yield, and the possibility of mass production compatible with current semiconductor production processes. Fabricated using a conductive paste and an epoxy resin that are both biocompatible, the developed micro-pyramidal array electrode operates in a conformal, non-invasive manner, with low skin irritation, which ensures improved comfort for brief or extended use. The operation of the developed electrode was examined by analyzing electrode-skin-electrode impedance, electroencephalography, electrocardiography, and electromyography signals and comparing them with those measured simultaneously using gel electrodes.

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