Blood Test Predicts Alzheimer's Before PET

Researchers at Mass General Brigham report that serial blood levels of pTau217 forecast amyloid and tau plaque buildup in the brain before PET scans turn positive in a cohort of 317 older adults. The biomarker could be used to pre‑screen participants for trials and, eventually, to shift Alzheimer’s case detection earlier in routine care. — Earlier, cheaper detection changes who gets recruited into trials, when treatments or counseling start, and raises policy questions about validation standards, screening guidelines, and health‑system capacity.