Blood test may predict when Alzheimer's symptoms will begin

Researchers reported that blood levels of the protein p‑Tau217 followed a consistent pattern and that a model combining age and p‑Tau217 estimated symptom onset within about a three- to four-year margin in the study cohort.

Researchers at Washington University School of Medicine reported a blood test that measures the brain protein p‑Tau217 and may estimate when Alzheimer's symptoms will begin. The study, published in Nature Medicine, analyzed data from more than 600 participants enrolled in two long-term Alzheimer's research projects. The team modeled p‑Tau217 levels together with age and found a consistent rise in the protein long before memory loss appeared. The researchers noted the model has an estimated margin of error of about three to four years and said they do not currently recommend biomarker testing for cognitively unimpaired people. Key findings: - p‑Tau217 levels in plasma rose in a consistent pattern years before cognitive decline in the study participants, according to the report. - A statistical model using a person’s age and p‑Tau217 level estimated the likely timing of symptom onset with roughly a three- to four-year margin of error. - The researchers reported that earlier abnormal p‑Tau217 at younger ages was associated with a longer interval before symptoms (for example, about 20 years from age 60) and a shorter interval when abnormality appeared at older ages (about 10 years from age 80). - The study cohorts were largely White and well-educated, and the authors cautioned that the results may not generalize to broader populations. Summary: If validated and expanded, the approach could influence how researchers design clinical trials and how people at elevated risk are identified years before cognitive decline. The study team plans to refine models by researching additional biomarkers and enrolling more diverse participants. Two large trials are currently underway to test whether people with high p‑Tau217 levels benefit from early treatment with one of two approved anti-amyloid therapies.