New Blood Test Predicts Alzheimer's Onset

New Alzheimer's blood tests that measure the p-tau217 protein offer potential for earlier disease detection. A study indicated these tests can predict the age of symptom onset with a median absolute error of approximately three to four years, correlating higher protein levels with earlier symptom appearance.

While these findings, published in Nature Medicine, require validation in diverse populations, they could accelerate research and clinical trials. The goal is to enable patients and doctors to plan for symptom prevention or slowing.

Two Alzheimer's blood tests have received FDA clearance for symptomatic adults aged 55 and over. However, experts, including the Alzheimer's Association, do not recommend their use in asymptomatic individuals. They stress that these tests are complementary tools, not standalone diagnostic solutions, and should be interpreted by healthcare professionals.

Despite limitations and variations in test accuracy, particularly in individuals with conditions like chronic kidney disease, blood tests are generally less expensive and more accessible than PET scans or MRIs. The Alzheimer's Association is advocating for expanded access through legislation like the ASAP Act, aiming for Medicare coverage of approved tests.