A Harvard-affiliated research team at Mass General Brigham has discovered that a blood test measuring plasma phosphorylated tau 217 (pTau217) could forecast Alzheimer’s disease progression long before symptoms or brain scan changes occur. This finding, published in Nature Communications, suggests this test could simplify disease prediction and identify those at risk of cognitive decline.
Lead author Hyun-Sik Yang, a neurology assistant professor at Harvard Medical School, noted, “We previously believed PET scans were the earliest indicators of Alzheimer’s, showing amyloid buildup a decade or more before symptoms. Now, pTau217 can be detected much earlier, even before amyloid PET scan abnormalities.” Last year, the FDA approved the first Alzheimer’s blood test, offering a less invasive and more affordable alternative to lumbar punctures and PET scans. The study by Yang and his team adds significant evidence supporting the predictive capabilities of blood tests.
The prospective cohort study tracked 317 older adults, aged 50 to 90, from the Harvard Aging Brain Study over an average of eight years. Participants underwent blood tests for pTau217, amyloid and tau PET scans, and cognitive assessments. The researchers assessed whether baseline and changing pTau217 levels could predict future amyloid accumulation, tau protein misfolding in brain neurons, and cognitive decline.
Results indicated that higher pTau217 levels predicted faster Alzheimer’s pathology buildup, even when initial brain scans were normal. pTau217 increases often preceded positive amyloid PET scans, underscoring the biomarker’s early detection capability. Importantly, participants with low initial pTau217 levels were unlikely to develop significant amyloid-beta on their PET scans over the follow-up period. These amino acid fragments are crucial in forming the sticky plaques characteristic of Alzheimer’s.
Yang stated, “Our study highlights that even when clinic amyloid scans are normal, the pTau217 biomarker can identify those who later become amyloid-positive. It also indicates that individuals with low pTau217 levels are likely to remain amyloid-negative for years.” While recommending pTau217 testing for older adults is premature, Yang and his colleagues anticipate the study’s findings will aid in clinical trials for Alzheimer’s prevention and help identify high-risk individuals.
Biomarker blood tests may eventually become routine health maintenance tools, offering a cost-effective alternative to amyloid PET scans. Co-senior author Jasmeer Chhatwal, an HMS neurology associate professor, expressed excitement about the rapid translation of research discoveries into clinical applications.
Original Source: news.harvard.edu
