The Study
Diagnostic Accuracy of Plasma p-tau217 as a Pre-Screening Tool for Amyloid-PET: A Decision Curve Analysis in the ADNI Cohort
This study found that if someone has a lot of p-tau217 in their blood, they’re very likely to have sticky amyloid plaques in their brain — like a red flag that matches what a brain scan shows. But it doesn’t prove the blood marker causes the plaques, or that everyone with high levels will get Alzheimer’s.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists tested a blood marker called p-tau217 to see if it could spot Alzheimer's brain plaques without needing an expensive brain scan.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means doctors could use this blood test to safely skip brain scans for most people who likely don't have plaques, saving time, money, and reducing patient stress.
- 2If p-tau217 is below 0.106 pg/mL, there's a 94% chance you don't have plaques.
- 3If it's above 0.177 pg/mL, there's an 86% chance you do.
- 4It worked almost as well as complex models using multiple blood tests.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Dementia and Alzheimer's Disease
Year
2026
Authors
Paolo Ribisi, V. Blandino, T. Piccoli
Related Content
Claims (6)
Using a blood test for p-tau217 to screen patients for Alzheimer's disease results in better clinical outcomes than ordering amyloid-PET scans for everyone, when evaluated across multiple risk thresholds.
In people with confirmed brain amyloid buildup, plasma levels of p-tau217 are higher than in those without amyloid buildup, and p-tau217 distinguishes these groups more clearly than other blood biomarkers like Aβ42/40, GFAP, or NfL.
In older adults with cognitive concerns, a blood test measuring p-tau217 above 0.177 pg/mL correctly identifies 78.9% of individuals with Alzheimer’s-related brain amyloid plaques and correctly rules out 86.0% of those without them.
A blood test measuring p-tau217 at 0.106 pg/mL correctly identifies 94.6% of people who do not have brain amyloid plaques and rules out the need for a costly brain scan in 93.7% of those cases.
A blood test measuring p-tau217 can accurately identify whether a person has amyloid plaques in the brain, matching the accuracy of more complex tests that combine multiple biomarkers.
Blood levels of p-tau217 can identify the presence of amyloid-beta plaques in the brain with 95% to 97% accuracy, allowing Alzheimer's pathology to be detected decades before symptoms appear.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.