| 21. |
- Pascoal, T. A., et al.
(författare)
-
Longitudinal 18F-MK-6240 tau tangles accumulation follows Braak stages
- 2021
-
Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 144:11, s. 3517-3528
-
Tidskriftsartikel (refereegranskat)abstract
- Tracking longitudinal tau tangles accumulation across the Alzheimer's disease continuum is crucial to better understand the natural history of tau pathology and for clinical trials. Although the available first-generation tau PET tracers detect tau accumulation in symptomatic individuals, their nanomolar affinity offers limited sensitivity to detect early tau accumulation in asymptomatic subjects. Here, we hypothesized the novel subnanomolar affinity tau tangles tracer 18F-MK-6240 can detect longitudinal tau accumulation in asymptomatic and symptomatic subjects. We studied 125 living individuals (65 cognitively unimpaired elderly amyloid-β-negative, 22 cognitively unimpaired elderly amyloid-β-positive, 21 mild cognitive impairment amyloid-β-positive and 17 Alzheimer's disease dementia amyloid-β-positive individuals) with baseline amyloid-β 18F-AZD4694 PET and baseline and follow-up tau 18F-MK-6240 PET. The 18F-MK-6240 standardized uptake value ratio (SUVR) was calculated at 90-110 min after tracer injection and the cerebellar crus I was used as the reference region. In addition, we assessed the in vivo18F-MK-6240 SUVR and post-mortem phosphorylated tau pathology in two participants with Alzheimer's disease dementia who died after the PET scans. We found that the cognitively unimpaired amyloid-β-negative individuals had significant longitudinal tau accumulation confined to the PET Braak-like stage I (3.9%) and II (2.8%) areas. The cognitively unimpaired amyloid-β-positive individuals showed greater tau accumulation in Braak-like stage I (8.9%) compared with later Braak stages. The patients with mild cognitive impairment and those who were Alzheimer's dementia amyloid-β-positive exhibited tau accumulation in Braak regions III-VI but not I-II. Cognitively impaired amyloid-β-positive individuals that were Braak II-IV at baseline displayed a 4.6-7.5% annual increase in tau accumulation in the Braak III-IV regions, whereas those who were cognitively impaired amyloid-β-positive Braak V-VI at baseline showed an 8.3-10.7% annual increase in the Braak regions V-VI. Neuropathological assessments confirmed PET-based Braak stages V-VI in the two brain donors. Our results suggest that the 18F-MK-6240 SUVR is able to detect longitudinal tau accumulation in asymptomatic and symptomatic Alzheimer's disease. The highest magnitude of 18F-MK-6240 SUVR accumulation moved from the medial temporal to sensorimotor cortex across the disease clinical spectrum. Trials using the 18F-MK-6240 SUVR in cognitively unimpaired individuals would be required to use regions of interest corresponding to early Braak stages, whereas trials in cognitively impaired subjects would benefit from using regions of interest associated with late Braak stages. Anti-tau trials should take into consideration an individual's baseline PET Braak-like stage to minimize the variability introduced by the hierarchical accumulation of tau tangles in the human brain. Finally, our post-mortem findings supported use of the 18F-MK-6240 SUVR as a biomarker to stage tau pathology in patients with Alzheimer's disease. © 2021 The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: journals.permissions@oup.com.
|
|
| 22. |
- Yakoub, Y., et al.
(författare)
-
Longitudinal blood biomarker trajectories in preclinical Alzheimer's disease
- 2023
-
Ingår i: Alzheimers & Dementia. - 1552-5260. ; 19:12, s. 5620-5631
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Plasma biomarkers are altered years prior to Alzheimer's disease (AD) clinical onset. Methods: We measured longitudinal changes in plasma amyloid-beta (A beta)(42/40) ratio, pTau181, pTau231, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) in a cohort of older adults at risk of AD (n = 373 total, n = 229 with A beta and tau positron emission tomography [PET] scans) considering genetic and demographic factors as possible modifiers of these markers' progression. Results: A beta(42/40) ratio concentrations decreased, while NfL and GFAP values increased over the 4-year follow-up. Apolipoprotein E (APOE) epsilon 4 carriers showed faster increase in plasma pTau181 than non-carriers. Older individuals showed a faster increase in plasma NfL, and females showed a faster increase in plasma GFAP values. In the PET subsample, individuals both A beta-PET and tau-PET positive showed faster plasma pTau181 and GFAP increase compared to PET-negative individuals. Discussion: Plasma markers can track biological change over time, with plasma pTau181 and GFAP markers showing longitudinal change in individuals with preclinical AD.
|
|
| 23. |
- Schaffer Aguzzoli, Cristiano, et al.
(författare)
-
Neuropsychiatric Symptoms and Microglial Activation in Patients with Alzheimer Disease
- 2023
-
Ingår i: JAMA network open. - 2574-3805. ; 6:11
-
Tidskriftsartikel (refereegranskat)abstract
- Importance: Neuropsychiatric symptoms are commonly encountered and are highly debilitating in patients with Alzheimer disease. Understanding their underpinnings has implications for identifying biomarkers and treatment for these symptoms. Objective: To evaluate whether glial markers are associated with neuropsychiatric symptoms in individuals across the Alzheimer disease continuum. Design, Setting, and Participants: This cross-sectional study was conducted from January to June 2023, leveraging data from the Translational Biomarkers in Aging and Dementia cohort at McGill University, Canada. Recruitment was based on referrals of individuals from the community or from outpatient clinics. Exclusion criteria included active substance abuse, major surgery, recent head trauma, safety contraindications for positron emission tomography (PET) or magnetic resonance imaging, being currently enrolled in other studies, and having inadequately treated systemic conditions. Main Outcomes and Measures: All individuals underwent assessment for neuropsychiatric symptoms (Neuropsychiatry Inventory Questionnaire [NPI-Q]), and imaging for microglial activation ([11C]PBR28 PET), amyloid-β ([18F]AZD4694 PET), and tau tangles ([18F]MK6240 PET). Results: Of the 109 participants, 72 (66%) were women and 37 (34%) were men; the median age was 71.8 years (range, 38.0-86.5 years). Overall, 70 had no cognitive impairment and 39 had cognitive impairment (25 mild; 14 Alzheimer disease dementia). Amyloid-β PET positivity was present in 21 cognitively unimpaired individuals (30%) and in 31 cognitively impaired individuals (79%). The NPI-Q severity score was associated with microglial activation in the frontal, temporal, and parietal cortices (β=7.37; 95% CI, 1.34-13.41; P=.01). A leave-one-out approach revealed that irritability was the NPI-Q domain most closely associated with the presence of brain microglial activation (β=6.86; 95% CI, 1.77-11.95; P=.008). Furthermore, we found that microglia-associated irritability was associated with study partner burden measured by NPI-Q distress score (β=5.72; 95% CI, 0.33-11.10; P=.03). Conclusions and Relevance: In this cross-sectional study of 109 individuals across the AD continuum, microglial activation was associated with and a potential biomarker of neuropsychiatric symptoms in Alzheimer disease. Moreover, our findings suggest that the combination of amyloid-β- and microglia-targeted therapies could have an impact on relieving these symptoms.
|
|
| 24. |
|
|
| 25. |
|
|
