07/20/2026
A new study suggests a blood test may someday help identify healthy older adults who are at higher risk of developing Alzheimer’s symptoms years in advance.
The test measures p-tau217, a form of tau connected to Alzheimer’s-related changes in the brain.
Researchers found that symptom-free older adults with very high levels of p-tau217 had a 38% risk of developing cognitive impairment within five years. That risk rose to 78% over 10 years, though researchers noted there is less confidence in the 10-year estimate.
For now, scientists say the test may be most useful for research, including identifying people who could participate in studies of possible Alzheimer’s treatments or prevention strategies.
They also caution that the test is not yet precise enough to guide an individualized prognosis for healthy people.
The broader takeaway: medical advances can create promising new tools, but timing, accuracy, and clinical usefulness matter. For now, researchers still emphasize familiar brain-health habits, including eating well, sleeping well, exercising, and staying socially engaged.
A blood test that helps diagnose Alzheimer's might also forecast if healthy older adults will develop symptoms.