TUESDAY, Feb. 24, 2026 (HealthDay News) -- A new model can predict when someone is likely to develop symptoms of Alzheimer disease (AD) using a single blood test, according to a study published online Feb. 19 in Nature Medicine.
Kellen K. Petersen, Ph.D., from Washington University in St. Louis, and colleagues used longitudinal plasma %p-tau217 (the ratio of phosphorylated to non-phosphorylated tau at position 217) from two independent cohorts (a total of 603 patients) to create clock models to estimate the age at plasma %p-tau217 positivity.
The researchers found that the estimated age at plasma %p-tau217 positivity was associated with the age at onset of AD symptoms (adjusted R2 of 0.337 to 0.612) with a median absolute error of 3.0 to 3.7 years. The time from %p-tau217 positivity to onset of AD symptoms was markedly shorter in older individuals.
"Our work shows the feasibility of using blood tests, which are substantially cheaper and more accessible than brain imaging scans or spinal fluid tests, for predicting the onset of Alzheimer’s symptoms," senior author Suzanne E. Schindler, M.D., Ph.D., also from WashU, said in a statement. "In the near term, these models will accelerate our research and clinical trials. Eventually, the goal is to be able to tell individual patients when they are likely to develop symptoms, which will help them and their doctors to develop a plan to prevent or slow symptoms."
Several authors disclosed ties to the pharmaceutical industry, including to several companies that helped fund the study.