A new study has identified that a simple blood test measuring the biomarker p-tau217 may predict the risk of cognitive decline in cognitively healthy older adults up to a decade before symptoms appear. The findings, which were presented at the Alzheimer’s Association International Conference in London and published in The Journal of the American Medical Association, offer a potential new tool for identifying individuals at high risk for Alzheimer’s disease.
Study Methodology and Key Findings
The research involved one of the largest analyses of its kind, tracking 2,684 cognitively healthy adults with an average age of 70 across six international research groups in North America, Japan, and Australia. The researchers found that symptom-free individuals with very high levels of p-tau217 had an estimated 38% risk of developing cognitive impairment within five years and an estimated 78% risk within 10 years. Those with moderately elevated levels faced a 45% risk over a decade. Lead study author Rachel Buckley, an associate professor of neurology at Harvard Medical School and investigator at the Mass General Brigham Neuroscience Institute, stated that the findings provide some of the clearest evidence to date that dementia risk can be detected years before memory problems begin. According to the study, p-tau217 provided predictive information beyond what is currently offered by standard brain scans and genetic testing.
Understanding the Biomarker p-tau217
The p-tau217 protein is a modified form of tau, which forms tangles inside brain cells that contribute to neuronal collapse and death. The biomarker is also a strong indicator of the buildup of beta-amyloid plaques in the brain. While amyloid plaques can begin to collect in the brain decades before cognitive decline, not everyone with high levels of amyloid will progress to dementia. However, researchers suggest that the p-tau217 test may identify the critical moment when amyloid pathology begins to trigger the spread of disease, which Dr. Buckley described as the “wildfire” of the disease process.
Clinical Context and Expert Cautions
Despite the potential of the test, researchers and independent experts emphasized that the p-tau217 blood test is not currently recommended for routine screening in asymptomatic individuals. Dr. Reisa Sperling, the study’s senior author at the Mass General Brigham Neuroscience Institute, advised that healthy people should wait to be tested until there are actionable interventions available.
At this point it wouldn’t change what I would tell someone to do,
Dr. Sperling said. I’d still tell them to eat well, sleep well, exercise a lot and stay engaged.
Future Implications for Research and Diagnosis
Experts suggest the primary immediate utility of the test lies in research and clinical trials. By identifying high-risk individuals, researchers can more efficiently recruit participants for clinical trials testing preventive strategies. As disease-modifying therapies, such as lecanemab and donanemab, continue to enter the medical landscape, the need for accessible biomarkers to guide monitoring and treatment decisions becomes increasingly important.
Related reading