Public Health & Aging

A new study in JAMA Network Open led by University of California San Diego researchers reports that levels of the blood biomarker phosphorylated tau 217 (p‑tau217) can strongly predict which older women will develop mild cognitive impairment or dementia as much as 25 years later. Investigators analyzed late‑1990s blood samples from 2,766 participants in the Women’s Health Initiative Memory Study, all women ages 65 to 79 without cognitive problems at baseline, and tracked them for up to a quarter‑century. Women with higher p‑tau217 at the start were much more likely to develop dementia, with particularly poor cognitive outcomes among those over 70 and carriers of the APOE ε4 Alzheimer’s risk gene, and the marker also appeared to be a stronger predictor in women assigned to estrogen‑progestin hormone therapy. The authors say blood‑based biomarkers like p‑tau217, while not yet ready for routine screening in symptom‑free people, could eventually allow far earlier identification of high‑risk patients and enable prevention trials, closer monitoring, and more targeted counseling long before memory loss emerges. Experts stress that such tests are less invasive and potentially more accessible than brain scans or spinal fluid analysis, underscoring how this line of research could reshape dementia detection and policy in an aging U.S. population.