Longevity & AgingBlood test flags Alzheimer's risk up to 10 years before symptoms appear
Alzheimer's disease begins damaging the brain years before memory problems show up, and a new international study suggests a simple blood test can flag who is most at risk. Researchers led by Mass General Brigham pooled data from six studies across North America, Japan, and Australia, covering 2,684 older adults with normal thinking at the start. They measured a blood marker called phosphorylated tau 217 (p-tau217). Among people with very high levels, the estimated chance of developing cognitive impairment was 38% within five years and 78% within 10 years, though the 10-year estimate rests on much less data. About 478 participants eventually developed impairment. The marker added predictive information beyond other established risk factors. The findings were published in JAMA and presented at the Alzheimer's Association International Conference. The work points toward earlier intervention and prevention before memory loss begins, though how to act on a result is still being worked out.
