A blood test already approved in the United States to diagnose Alzheimer's disease may also predict cognitive decline years before memory loss appears in symptom-free older adults, according to research published in JAMA and presented at the Alzheimer's Association International Conference in London.
The test measures p-tau217, a tau protein linked to amyloid plaque and tangle buildup in the brain. Researchers at Mass General Brigham in Boston, led by senior author Reisa Sperling, analyzed data from 2,684 cognitively healthy older adults across North America, Japan, and Australia. Of those, 478 developed cognitive impairment during nearly two decades of follow-up. Asymptomatic individuals with the highest p-tau217 levels faced a 38% risk of cognitive impairment within five years, rising to 78% within ten.
The test is currently approved only for adults over 55 with existing cognitive problems, and experts caution healthy individuals against seeking it outside research settings.