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.

scholarly journals Non-Invasive Diagnostic Biomarkers for Alzheimer’s Disease

2021 ◽  
Vol 3 (1) ◽  
pp. 12-18
Author(s):  
Shyamasri Biswas ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Early Stage ◽  
Clinical Success ◽  
Potential Game ◽  
Diagnostic Biomarkers ◽  
Non Invasive ◽  
Presymptomatic Stage ◽  
The Subject ◽  
Made In

The emergence of biomarkers in biologic fluids is considered an important milestone in the field of Alzheimer’s disease (AD) research. Biomarkers are widely considered critically important for the diagnosis and therapeutic intervention of the disease. It is believed that an early diagnosis of AD at a presymptomatic stage could provide the key for a successful intervention and treatment of AD. It is due to the reason that preventative and therapeutic strategies that are known to be AD stage-dependent can have a better chance of clinical success at a very early stage of the disease when critical neurons are not lost. To this end, current clinical trials are extensively being employed by taking advantage of different diagnostic biomarkers. While there has been notable progress in biomarkers for AD, the current research emphasis has been on exploring non-invasive biomarkers due to the advantages of cost-effectiveness, rapid diagnosis and significantly less medical procedural complexities that make these biomarkers potential game changer in AD diagnostics. Here, we present a bird eye view on the subject and discuss the progress made in important non-invasive biomarkers for AD.

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.

Serum Ferritin Levels in Alzheimer's Disease: A Meta-Analysis (Preprint)

2020 ◽  
Author(s):  
Praveen Parthasarathy
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Iron Overload ◽  
Serum Ferritin ◽  
Meta Analysis ◽  
Iron Storage ◽  
Blood Biomarker ◽  
Pubmed Database ◽  
Healthy Control

BACKGROUND The role of iron overload in Alzheimer’s Disease (AD) pathology has been investigated in previous years, but mechanisms underlying overload remain unclear. Ferritin is an iron storage and transport protein that has been associated with inflammation and neurodegenerative disease. OBJECTIVE The objective of this study was to evaluate if serum ferritin levels in AD subjects are significantly higher than serum ferritin levels among a healthy control. METHODS A systematic literature search of the PubMed database yielded fifty publications, culminating in two studies that were used in statistical analysis. RESULTS Our results showed that pooled serum ferritin levels were significantly higher in AD patients than in healthy controls [SMD: 1.06, 95 % CI: (0.68, 1.43), z = 5.53, p ≈ 0.00]. CONCLUSIONS Findings from this study suggest that serum ferritin may be a potent blood biomarker for AD. Research must be conducted to further evaluate the role of serum ferritin as a neurotoxic, neuroprotective, or an indicator molecule in AD pathology. We propose that increased serum ferritin levels in AD may contribute to neuroinflammation and iron overload in neuroglia.

scholarly journals Use of eye biomarkers in pre-clinical diagnosis of Alzheimer’s Disease

2021 ◽  
Author(s):  
Luísa França de Faria ◽  
Fernanda Roberti Gil de Paula ◽  
Gabriel Roncalli Soalheiro Prado Alves ◽  
Luiz Filipe de Oliveira Braga ◽  
Lilian Caiafa Ferreira Machado ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Symptoms ◽  
Ocular Blood Flow ◽  
Unknown Etiology ◽  
Disease Biomarkers ◽  
Non Invasive ◽  
Amyloid Aβ ◽  
Eye Exams ◽  
Detection Of Biomarkers

Background: Alzheimer’s disease (AD) has an unknown etiology, but the main pathophysiological hypothesis consists of the accumulation of extracellular beta- amyloid (Aβ) plaques and the formation of intracellular neurofibrillary tangles of phosphorylated tau1,2. As brain changes follow the appearance of clinical symptoms, there is a difficulty in making the diagnosis and early treatment3,4. The detection of biomarkers in the retina guaranteed the preclinical diagnosis of AD, in an efficient and economical way5. Objectives: To highlight the application of ocular biomarkers in the early diagnosis of AD. Methods: This is a narrative review with search in the sources PubMed, Cochrane and TripDatabase using descriptors: “Alzheimer Disease”, “Biomarkers” and “Retina”. Seven articles were used, published from 2017 to 2021. Results: In patients with pre-clinical AD, accumulation of Aβ was detected with the formation of specifically smaller retinal plaques when compared to brain plaques, but quantitatively equivalent to the load of this protein in the brain and the severity of this pathology6. Thus, associated with the great advance in retinal imaging exams, AD can be diagnosed early by analyzing the structure of the retina and ocular blood flow in a non-invasive and efficient manner5,7. Instruments and systems for conducting eye exams, such as optical coherence tomography and retinography, are increasingly present in medical services, which makes it possible to carry out regular and constant tests in the population1,5. Conclusions: Further studies are required to verify the long- term application of ocular biomarkers in medical practice.

scholarly journals New approaches for Alzheimer early detection

2021 ◽  
Author(s):  
Jordy Silva de Carvalho ◽  
Marina Galdino da Rocha Pitta ◽  
César Augusto Souza de Andrade
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Early Detection ◽  
Biological Fluids ◽  
The Elderly ◽  
Diagnostic Techniques ◽  
Csf Biomarkers ◽  
Non Invasive ◽  
Pubmed Database ◽  
The Brain

Background: Alzheimer’s disease (AD) is neurodegenerative and complex, characterized by the progressive loss of neurons, causing cognitive deficits. It’s the leading cause of dementia in the elderly, affecting about 35.6 million people worldwide. The high costs of invasive diagnostic techniques have limited early detection and intervention. Objectives: This review approached some new non-invasive diagnostic techniques involved in AD. Methods: The descriptors used were “Alzheimer’s Disease”, “Biomarkers” and “Early diagnosis”. PubMed database was used during the period of 2016-2021. Articles not related to the proposed theme were excluded, leaving 4 articles. Results: In the last few years, great advances have been made in diagnosing AD, such as brain NMR, CSF biomarkers, Pittsburgh compound B and brain PET scan. Beta-amyloid proteins (βA) and TAU in CSF are the only available markers for AD diagnosis in the clinic. The main limitations are early detection, differential diagnosis and progress disease report. Salivary biomarkers are being studied as a simple non-invasive diagnostic tool, with βA1-42/1-40 and pTAU being the most investigated in AD. Acting as a window on the brain, the retina can reflect the pathogenesis of the brain, with a focus on neurodegeneration and microvascular changes measured using optical coherence tomography technologies. Conclusions: Several criteria have been proposed for the diagnosis of AD, including biomarkers, biological fluids and brain changes detectable by imaging. Early detection of AD is vitally important, as it’ll allow patients to receive adequate and individualized information, care and support.

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