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- Adamczuk, Katarzyna, et al.
(författare)
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Diagnostic value of cerebrospinal fluid A beta ratios in preclinical Alzheimer's disease
- 2015
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Ingår i: Alzheimer's Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: In this study of preclinical Alzheimer's disease (AD) we assessed the added diagnostic value of using cerebrospinal fluid (CSF) A beta ratios rather than A beta 42 in isolation for detecting individuals who are positive on amyloid positron emission tomography (PET). Methods: Thirty-eight community-recruited cognitively intact older adults (mean age 73, range 65-80 years) underwent F-18-flutemetamol PET and CSF measurement of A beta 1-42, A beta 1-40, A beta 1-38, and total tau (ttau). F-18-flutemetamol retention was quantified using standardized uptake value ratios in a composite cortical region (SUVRcomp) with reference to cerebellar grey matter. Based on a prior autopsy validation study, the SUVRcomp cut-off was 1.57. Sensitivities, specificities and cut-offs were defined based on receiver operating characteristic analysis with CSF analytes as variables of interest and F-18-flutemetamol positivity as the classifier. We also determined sensitivities and CSF cut-off values at fixed specificities of 90 % and 95 %. Results: Seven out of 38 subjects (18 %) were positive on amyloid PET. A beta 42/ttau, A beta 42/A beta 40, A beta 42/A beta 38, and A beta 42 had the highest accuracy to identify amyloid-positive subjects (area under the curve (AUC) >= 0.908). A beta 40 and A beta 38 had significantly lower discriminative power (AUC = 0.571). When specificity was fixed at 90 % and 95 %, A beta 42/ttau had the highest sensitivity among the different CSF markers (85.71 % and 71.43 %, respectively). Sensitivity of A beta 42 alone was significantly lower under these conditions (57.14 % and 42.86 %, respectively). Conclusion: For the CSF-based definition of preclinical AD, if a high specificity is required, our data support the use of A beta 42/ttau rather than using A beta 42 in isolation.
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| 2. |
- De Meyer, Steffi, et al.
(författare)
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Plasma pTau181 and pTau217 predict asymptomatic amyloid accumulation equally well as amyloid PET
- 2024
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Ingår i: BRAIN COMMUNICATIONS. - 2632-1297. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic phase of preclinical Alzheimer's disease, as characterized by accumulating cortical amyloid-beta, is a window of opportunity for amyloid-beta-lowering therapies to have greater efficacy. Biomarkers that accurately predict amyloid-beta accumulation may be of critical importance for participant inclusion in secondary prevention trials and thus enhance development of early Alzheimer's disease therapies. We compared the abilities of baseline plasma pTau181, pTau217 and amyloid-beta PET load to predict future amyloid-beta accumulation in asymptomatic elderly. In this longitudinal cohort study, baseline plasma pTau181 and pTau217 were quantified using single molecule array assays in cognitively unimpaired elderly selected from the community-recruited F-PACK cohort based on the availability of baseline plasma samples and longitudinal amyloid-beta PET data (median time interval = 5 years, range 2-10 years). The predictive abilities of pTau181, pTau217 and PET-based amyloid-beta measures for PET-based amyloid-beta accumulation were investigated using receiver operating characteristic analyses, correlations and stepwise regression analyses. We included 75 F-PACK subjects (mean age = 70 years, 48% female), of which 16 were classified as amyloid-beta accumulators [median (interquartile range) Centiloid rate of change = 3.42 (1.60) Centiloids/year). Plasma pTau181 [area under the curve (95% confidence interval) = 0.72 (0.59-0.86)] distinguished amyloid-beta accumulators from non-accumulators with similar accuracy as pTau217 [area under the curve (95% confidence interval) = 0.75 (0.62-0.88) and amyloid-beta PET [area under the curve (95% confidence interval) = 0.72 (0.56-0.87)]. Plasma pTau181 and pTau217 strongly correlated with each other (r = 0.93, P-false discovery rate < 0.001) and, together with amyloid-beta PET, similarly correlated with amyloid-beta rate of change (r(pTau181) = 0.33, r(pTau217) = 0.36, r(amyloid-beta PET) = 0.35, all P-false discovery rate <= 0.01). Addition of plasma pTau181, plasma pTau217 or amyloid-beta PET to a linear demographic model including age, sex and APOE-epsilon 4 carriership similarly improved the prediction of amyloid-beta accumulation (Delta Akaike information criterion <= 4.1). In a multimodal biomarker model including all three biomarkers, each biomarker lost their individual predictive ability. These findings indicate that plasma pTau181, plasma pTau217 and amyloid-beta PET convey overlapping information and therefore predict the dynamic phase of asymptomatic amyloid-beta accumulation with comparable performances. In clinical trial recruitment, confirmatory PET scans following blood-based prescreening might thus not provide additional value for detecting participants in these early disease stages who are destined to accumulate cortical amyloid-beta. Given the moderate performances, future studies should investigate whether integrating plasma pTau species with other factors can improve performance and thus enhance clinical and research utility.
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