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Plasma p-tau217 Clocks for Predicting Onset of Alzheimer Disease

Predicting onset of symptomatic Alzheimer's disease with plasma p-tau217 clocks

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Year of Publication: 2026

Journal: Nature Medicine

Clinical Question

Can plasma p-tau217 trajectories predict when a cognitively normal person will develop symptomatic Alzheimer disease?

Bottom Line

Longitudinal p-tau217 trajectories predict AD symptom onset years in advance. The rate of p-tau217 increase provides the most accurate prognostic information for preclinical AD.

Major Points

  • Developed 'p-tau217 clocks' — trajectory models using serial blood measurements to predict time to symptomatic AD.
  • Rate of p-tau217 change over time was a superior predictor vs single time-point measurement (P<0.05).
  • Trajectory models significantly outperformed single measurements for predicting conversion (P<0.001).
  • Prediction improved when combined with age, APOE genotype, and sex.
  • Moves the field from diagnostic ('do you have AD?') to prognostic ('when will you get symptoms?') blood testing.

Design

Study Type: Longitudinal biomarker cohort study

Criticisms

  • Requires multiple blood draws over time — less practical than single time-point testing
  • Prediction accuracy depends on number and spacing of serial measurements
  • Ethical implications of predicting AD onset decades before symptoms are profound and unresolved
  • Validated in research cohorts — performance in diverse clinical populations unknown
  • Does not account for potential disease-modifying interventions that could alter trajectory

Based on: Plasma p-tau217 Clocks for Predicting Onset of Alzheimer Disease (Nature Medicine, 2026)

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