Alzheimer’s Disease and Dementia

A study from Washington University School of Medicine in St. Louis, published in Nature Medicine, finds that a single blood test measuring levels of the brain protein p‑Tau217 can not only flag a person’s risk for Alzheimer’s disease but also estimate, within about three to four years, when symptoms are likely to begin. Analyzing more than 600 older adults enrolled in long‑term research cohorts, the team showed that p‑Tau217 levels rise in a consistent pattern years before memory loss, allowing a model that combines age and protein level to act as a kind of biological clock. Lead author Kellen K. Petersen, PhD, told Fox News Digital that people whose p‑Tau217 first became abnormal around age 60 developed symptoms roughly 20 years later, while those first abnormal at 80 showed symptoms in about 10 years, suggesting age and brain changes speed clinical onset. Outside expert Rebecca Edelmayer of the Alzheimer’s Association said such a relatively cheap blood test could transform how researchers design prevention trials and eventually help clinicians identify patients who might benefit from early treatment, though she and Petersen stress it is not yet recommended for cognitively normal people outside research. The work adds to a fast‑moving shift away from expensive brain scans and spinal‑fluid tests toward blood‑based biomarkers that could make early Alzheimer’s detection and risk stratification far more accessible in routine U.S. care.