- Baseline plasma p-tau217 thresholds predicted Aβ-PET positivity with 86% to 95% accuracy sustained for up to five years.
- Most p-tau217-positive individuals remained stable (93% to 98%); intermediate zone participants progressed to positive more often than negatives.
- Stable-positive and progress-to-positive profiles exhibited more Aβ abnormalities, accelerated tau accumulation, greater hippocampal atrophy, and higher dementia incidence.
Alzheimers Dement. 2026 Sep;22(9):e71783. doi: 10.1002/alz.71783.
ABSTRACT
INTRODUCTION: Longitudinal diagnostic and prognostic validity of plasma phosphorylated tau217 (p-tau217) in Alzheimer’s disease (AD) remains uncertain.
METHODS: In this multi-cohort study of 2117 individuals, we established baseline plasma p-tau217 thresholds for amyloid-β-positron emission tomography (Aβ-PET) and assessed their longitudinal classification stability and prognostic relevance for AD-related outcomes.
RESULTS: Baseline-defined cutoffs achieved high and sustained accuracy (86%-95%) for Aβ-PET positivity over up to 5 years of follow-up. Longitudinally, most p-tau217-positive individuals remained stable (93%-98%), whereas the intermediate zone group progressed more to positive (44%-78%) than p-tau217-negative individuals (4%-21%). Participants with stable-positive and progress-to-positive p-tau217 profiles more frequently exhibited Aβ abnormalities (90%-100% and 64%-96%, respectively) and experienced accelerated tau accumulation, hippocampal atrophy, and incident dementia compared to those with a stable-negative p-tau217 profile.
DISCUSSION: These findings support the high stability and Aβ-PET classification performance of longitudinal plasma p-tau217 monitoring in AD, providing a scalable tool for risk stratification and disease monitoring.
PMID:42669630 | DOI:10.1002/alz.71783
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