Tau PET imaging with [18F]flortaucipir allows for the visualization and mapping of aggregated tau deposits, a key neuropathologic feature of Alzheimer disease (AD). A visual interpretation method for [18F]flortaucipir was approved by the Food and Drug Administration and European Medicines Agency and has been implemented for a standardized, clinically usable definition of tau PET positivity. The CenTauRz method, on the other hand, offers the possibility to harmonize the definition of tau PET positivity across different radiotracers using quantitative metrics, but its concordance with clinically relevant [18F]flortaucipir visual reads remains unclear. Methods: A convenience sample of 3991 participants, including cognitively unimpaired (CU) and cognitively impaired (CI) individuals (i.e., those with mild cognitive impairment or AD dementia), underwent [18F]flortaucipir PET imaging. Each [18F]flortaucipir scan was assessed by 3 trained readers using the approved visual interpretation method and quantified using the CenTauRz quantification pipeline in different regions of interest (ROIs). Concordance between positive visual reads and CenTauRz-defined positivity (i.e., >2 on the CenTauRz scale) was assessed using Cohen κ. Receiver-operating-characteristic (ROC) analysis evaluated the discriminative power of continuous CenTauRz values in distinguishing between negative and positive visual reads. Generalized additive models examined clinical progression on the basis of visual and CenTauRz-based assessments of tau PET positivity. Results: Concordance between visual reads and CenTauRz-based assessments of tau PET positivity was moderate, particularly in CU individuals (κ = 0.23-0.55 for CU participants, κ = 0.57-0.82 for CI participants, depending on the ROI). ROC analysis revealed that the agreement remained moderate, independent of the CenTauRz cut point used (area under the ROC curve, 0.72-0.87 vs. 0.87-0.97 for CU and CI individuals, respectively). Among discordant cases, participants with visually positive/CenTauRz-negative tau PET scans were more frequently amyloid-positive and exhibited faster clinical progression compared with visually negative/CenTauRz-positive individuals. Conclusion: Our findings highlight the relatively limited agreement between the visual assessment of [18F]flortaucipir PET images and CenTauRz-based quantification, particularly in CU individuals. Participants with visually positive/CenTauRz-negative tau PET scans showed a high frequency of amyloid positivity and faster clinical progression, suggesting that visual reads are more sensitive to heterogeneous, clinically relevant tau accumulation patterns not captured by ROI-based methods. These findings underscore the need for new quantification approaches to better capture the complex patterns of tau deposition, important for early AD detection and monitoring.
Stamatia Karagianni, Alexis Moscoso, Sheelakumari Raghavan et al.· Journal of Nuclear Medicine· 0 citations
Importance
Classifying disease based on underlying pathobiology rather than clinical phenotype has implications for the development of biomarkers and therapy development.
Observations
Transactive response DNA-binding protein 43 kDa (TDP-43) pathology is observed across a range of clinically defined neurodegenerative disorders including limbic predominant age-related encephalopathy (LATE), most cases of amyotrophic lateral sclerosis (ALS), inclusion body myositis, multisystem proteinopathy, and approximately half the cases of frontotemporal dementia (FTD). Despite this shared biology, the current nosology for these neurodegenerative disorders is based on their distinct clinical phenotypes. An alternative approach recognizes the central role of TDP-43 pathology in disease pathogenesis, reserving the use of clinical terms like ALS, FTD, or LATE to describe phenotypic manifestations of underlying pathobiology. This approach also recognizes the converging biomarker and neuropathological data indicating that pathology begins presymptomatically, before the overt clinical manifestations of disease appear.
Conclusions and Relevance
In proposing a pathobiological definition of disease, the goal is to provide a road map for developing biomarkers that accurately reflect the underlying pathobiology of disease and for advancing therapeutic candidates that effectively target fundamental disease mechanisms.
M. Benatar, SJ Barmada, Gregory A Jicha et al.· JAMA Neurology· 1 citation
Plasma p‐tau217 and p‐tau217/Aβ42 reliably identify non‐Hispanic White individuals with symptomatic and pre‐clinical AD. However, performance across ethnoracially diverse groups remains unknown.
Y. Piura, P. Aduen, Leah Schecter et al.· Alzheimer's & Dementia· 0 citations
OBJECTIVE
Magnetic resonance imaging (MRI)-visible enlarged perivascular spaces (PVS) are markers of cerebral small vessel disease (SVD) and aging, processes implicated in both neurodegenerative and cerebrovascular pathologies. However, longitudinal positron emission tomography (PET) studies examining PVS as a mechanism underlying Alzheimer's disease (AD) pathophysiological progression are lacking. Our overall objective was to investigate the associations of baseline PVS burden with white matter hyperintensity (WMH) volume, amyloid-PET, and tau-PET, both cross-sectionally and longitudinally.
METHODS
We examined 2,229 participants across the aging-AD spectrum from the Mayo Clinic Study of Aging (MCSA) and the Mayo Alzheimer's Disease Research Center (ADRC) (mean age = 68.59 ± 12.70 and 48.94% women). PVS and WMH were quantified using a novel in-house algorithm. Amyloid on [11C]Pittsburgh Compound B (PiB)-PET and tau on AV1451-PET were measured. Cross-sectional regional and global associations were examined using canonical correlation analysis (CCA). Longitudinal associations were examined using age- and sex-adjusted linear mixed effect (LME) models with natural splines and subject-wise 10-fold cross-validation.
RESULT
Three distinct associations were observed: (1) PVS in the basal ganglia (PVS-BG) was associated with greater WMH volume both cross-sectionally and longitudinally; (2) PVS-BG covaried with higher PiB standardized uptake value ratio (SUVR) cross-sectionally, with longitudinal trajectory associations limited to amyloid-negative individuals; (3) PVS in the centrum semiovale (PVS-CSO) was not associated with amyloid or tau, but was associated with occipital WMH, a pattern characteristic of CAA.
INTERPRETATION
Findings lend support for PVS-BG as an early indicator of small vessel dysfunction and WMH pathogenesis. Individuals with higher PVS-BG burden exhibited higher WMH burden and faster WMH progression, suggesting that PVS-BG may identify individuals at increased risk of progressive SVD. Evidence linking PVS to downstream AD biomarker progression was weaker. Findings support the relevance of PVS-CSO to CAA, suggesting that they may reflect changes occurring early in the disease process. ANN NEUROL 2026.
Audrey Low, J. Gunter, Mingzhao Hu et al.· Annals of Neurology· 0 citations
Diffusion MRI biomarkers were abnormal at least a decade before WMH abnormality in the population, revealing a prolonged phase of early SVD and highlighting their potential for SVD prevention.
P. Vemuri, Ming-Zhao Hu, Emily S. Lundt et al.· Stroke· 0 citations
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