Abstract
Although there is a consensus on the reduced levels of Aβ1-42 in the CSF of patients with AD, studies of plasma Aβ levels were inconsistent and have limited clinical value. We developed an immunomagnetic reduction assay (IMR) to determine the plasma levels of Aβ. We surveyed patients with varying AD severity (CDR = 0.5, n=16; CDR ≥ 1, n=18) and controls (n=26). Significant group differences were apparent in the levels of Aβ1-42 (F = 5.54, p = 0.002) and the Aβ1-42/Aβ1-40 ratio (F = 24.198, p < 0.001). Post-hoc analyses showed significant differences in the Aβ1-42 levels of controls and AD patients (p = 0.001) and in the Aβ1-42/Aβ1-40 ratio of control, MCI and AD subjects (all p ≤ 0.001). Regression analysis of Aβ1-42/Aβ1-40 ratios on dementia severity showed an adjusted R2 of 0.553 (p = 0.001). We identified a cut-off of 16.1 pg/ml for Aβ1-42 to differentiate control subjects from patients (both AD and MCI) with 85.3% sensitivity and 88.5% specificity. We also obtained a cut-off value of 0.303 for Aβ1-42/Aβ1-40 ratios with 85.3% sensitivity and 96.2% specificity. APOE ε4 carriers had significantly higher Aβ1-42/Aβ1-40 ratios than the non-carriers (F = 4.839, p = 0.015). An independent group of case-control subjects validated both cut-off values for Aβ1-42/Aβ1-40 (100% sensitivity and 83.3% specificity) and for Aβ1-42 (100% sensitivity and 75.3% specificity). In a subgroup of longitudinal follow- up study, we found that the plasma Aβ was relatively stable with an interval of approximately 3 months. In conclusion, we found that the plasma Aβ1-42 is a useful biomarker for AD. The Aβ1-42/Aβ1-40 ratio improves the diagnostic power of the plasma Aβ biomarkers. The iron nanoparticles and IMR provides a novel method to measure plasma Aβ and could serve as an important clinical tool for the diagnosis of neurodegenerative diseases.
Keywords: Plasma beta-amyloid, Alzheimer’s disease, mild cognitive impairment, immunomagnetic reduction assay, nanoparticles, neurofibrillary tangles, albumin, lipoproteins, carcinogens
Current Alzheimer Research
Title:New Assay for Old Markers-Plasma Beta Amyloid of Mild Cognitive Impairment and Alzheimer’s Disease
Volume: 9 Issue: 10
Author(s): M.J. Chiu, S.Y. Yang, T.F. Chen, J.J. Chieh, T.Z. Huang, P.K. Yip, H.C. Yang, T.W. Cheng, Y.F. Chen, M.S. Hua, H.E. Horng
Affiliation:
Keywords: Plasma beta-amyloid, Alzheimer’s disease, mild cognitive impairment, immunomagnetic reduction assay, nanoparticles, neurofibrillary tangles, albumin, lipoproteins, carcinogens
Abstract: Although there is a consensus on the reduced levels of Aβ1-42 in the CSF of patients with AD, studies of plasma Aβ levels were inconsistent and have limited clinical value. We developed an immunomagnetic reduction assay (IMR) to determine the plasma levels of Aβ. We surveyed patients with varying AD severity (CDR = 0.5, n=16; CDR ≥ 1, n=18) and controls (n=26). Significant group differences were apparent in the levels of Aβ1-42 (F = 5.54, p = 0.002) and the Aβ1-42/Aβ1-40 ratio (F = 24.198, p < 0.001). Post-hoc analyses showed significant differences in the Aβ1-42 levels of controls and AD patients (p = 0.001) and in the Aβ1-42/Aβ1-40 ratio of control, MCI and AD subjects (all p ≤ 0.001). Regression analysis of Aβ1-42/Aβ1-40 ratios on dementia severity showed an adjusted R2 of 0.553 (p = 0.001). We identified a cut-off of 16.1 pg/ml for Aβ1-42 to differentiate control subjects from patients (both AD and MCI) with 85.3% sensitivity and 88.5% specificity. We also obtained a cut-off value of 0.303 for Aβ1-42/Aβ1-40 ratios with 85.3% sensitivity and 96.2% specificity. APOE ε4 carriers had significantly higher Aβ1-42/Aβ1-40 ratios than the non-carriers (F = 4.839, p = 0.015). An independent group of case-control subjects validated both cut-off values for Aβ1-42/Aβ1-40 (100% sensitivity and 83.3% specificity) and for Aβ1-42 (100% sensitivity and 75.3% specificity). In a subgroup of longitudinal follow- up study, we found that the plasma Aβ was relatively stable with an interval of approximately 3 months. In conclusion, we found that the plasma Aβ1-42 is a useful biomarker for AD. The Aβ1-42/Aβ1-40 ratio improves the diagnostic power of the plasma Aβ biomarkers. The iron nanoparticles and IMR provides a novel method to measure plasma Aβ and could serve as an important clinical tool for the diagnosis of neurodegenerative diseases.
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M.J. Chiu, S.Y. Yang, T.F. Chen, J.J. Chieh, T.Z. Huang, P.K. Yip, H.C. Yang, T.W. Cheng, Y.F. Chen, M.S. Hua, H.E. Horng , New Assay for Old Markers-Plasma Beta Amyloid of Mild Cognitive Impairment and Alzheimer’s Disease, Current Alzheimer Research 2012; 9 (10) . https://dx.doi.org/10.2174/156720512804142967
DOI https://dx.doi.org/10.2174/156720512804142967 |
Print ISSN 1567-2050 |
Publisher Name Bentham Science Publisher |
Online ISSN 1875-5828 |
Call for Papers in Thematic Issues
New Advances in the Prevention, Diagnosis, Treatment, and Rehabilitation of Alzheimer's Disease
Aims and Scope: Introduction: Alzheimer's disease (AD) poses a significant global health challenge, with an increasing prevalence that demands concerted efforts to advance our understanding and strategies for prevention, diagnosis, treatment, and rehabilitation. This thematic issue aims to bring together cutting-edge research and innovative approaches from multidisciplinary perspectives to address ...read more
Current updates on the Role of Neuroinflammation in Neurodegenerative Disorders
Neuroinflammation is an invariable hallmark of chronic and acute neurodegenerative disorders and has long been considered a potential drug target for Alzheimer?s disease (AD) and dementia. Significant evidence of inflammatory processes as a feature of AD is provided by the presence of inflammatory markers in plasma, CSF and postmortem brain ...read more
Deep Learning for Advancing Alzheimer's Disease Research
Alzheimer's disease (AD) poses a significant global health challenge, with an increasing number of individuals affected yearly. Deep learning, a subfield of artificial intelligence, has shown immense potential in various domains, including healthcare. This thematic issue of Current Alzheimer Research explores the application of deep learning techniques in advancing our ...read more
Diagnostic and therapeutic biomarkers of dementia
Dementia affects 18 million people worldwide. Dementia is a syndrome of symptoms caused by brain disease, usually chronic or progressive, clinically characterized by multiple impairments of higher cortical functions such as memory, thinking, orientation, and learning. In addition, in the course of dementia, cognitive deficits are observed, which often hinder ...read more
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