Single blood test could predict Alzheimer's symptom onset years before signs

Researchers developed a model using plasma p‑tau217 that estimated the age of Alzheimer's symptom onset to within three to four years in a study of 603 older adults, and they released the model code and a web tool for exploration.

Researchers at Washington University School of Medicine describe a model that uses a single blood marker to estimate when Alzheimer's symptoms are likely to begin. The approach centers on plasma p‑tau217, a protein associated with amyloid and tau accumulation in the brain. The team analyzed data from 603 older adults who were living independently when they entered two research cohorts. Their results were published in Nature Medicine and the researchers shared code and a web tool to demonstrate the model. Key findings: - The prediction model relied on plasma p‑tau217, which reflects amyloid and tau pathologies linked to Alzheimer's. - Data came from 603 participants in the WashU Knight Alzheimer Disease Research Center and the Alzheimer's Disease Neuroimaging Initiative (ADNI). - The model estimated age of symptomatic onset to within about three to four years on average. - Performance was similar across different p‑tau217 assays, including testing with PrecivityAD2 and an assay that is reported as FDA cleared. - The team released their model-development code and a web-based tool so other researchers can examine the "clock" approach. Summary: The study reports that a blood-based p‑tau217 model can estimate when Alzheimer's symptoms may appear and that the method performed consistently across multiple tests. The researchers report further refinement and validation are planned, and they note potential uses in research and clinical trials; broader clinical application is undetermined at this time.