Plasma phosphorylated tau 217 (p-tau217) testing is recommended and approved for detecting Alzheimer’s disease (AD) in patients who have symptoms of cognitive impairment. Now a
study in
JAMA Neurology suggests that p-tau217 blood tests are highly accurate for identifying individuals with preclinical AD: those who have amyloid plaques in their brains but do not have cognitive impairment.
Why It’s Relevant
“The preclinical stage of AD is where therapeutic interventions will likely have the most impact in ameliorating disease progression by significantly delaying or preventing the onset of AD-related cognitive decline,” the study investigators wrote.
By the Numbers
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Researchers analyzed data from 18 studies encompassing 7,834 participants—2,533 amyloid-positive and 5,301 amyloid-negative—without cognitive impairment.
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Individuals who were amyloid-positive had significantly higher p-tau217 levels on average than those who were amyloid-negative (between-group effect size of 1.50).
- p-tau217 tests could identify amyloid-positive individuals with an overall accuracy of 87%.
The Other Side
The studies included in the meta-analysis were comprised primarily of highly educated White individuals, and it is unclear whether the findings could apply to populations with greater ethnic and socioeconomic diversity.
What’s Next
“Although the use of plasma p-tau217 assays is currently restricted to those who are symptomatic for AD, the findings of this meta-analysis will help justify its use as a routine screening measure in asymptomatic individuals once an effective preventative therapy becomes available,” the study investigators wrote.
Related Info
Source
Michael Malek-Ahmadi et al. JAMA Neurology. Published online December 1, 2025. doi: 10.1001/jamaneurol.2025.4721
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