Blood test detects Alzheimer’s risk years before brain scans

Tuesday 14 April 2026 - 16:00

By: Dakir Madiha

Blood test detects Alzheimer’s risk years before brain scans

A new study suggests a simple blood test can predict the progression of Alzheimer’s disease years before changes appear on brain scans. Researchers at Mass General Brigham reported the findings in Nature Communications, marking a significant step toward earlier detection of the disease.

The study tracked 317 cognitively healthy adults enrolled in the Harvard Aging Brain Study over an average of eight years. Scientists measured levels of a protein biomarker known as pTau217 in blood plasma, alongside repeated PET brain scans and cognitive assessments. The results showed that increases in pTau217 could be detected well before amyloid buildup becomes visible through imaging.

PET scans have long been considered one of the earliest tools for identifying Alzheimer’s pathology, often revealing amyloid accumulation 10 to 20 years before symptoms emerge. However, the new findings indicate that blood-based detection may precede even these early imaging signals. Participants with low pTau217 levels at the start of the study showed minimal risk of developing amyloid deposits during follow-up, suggesting the test could help identify individuals at low or high risk with greater precision.

Parallel advances in imaging are also reshaping the field. Researchers at Uppsala University described a new pretargeted PET imaging method in Translational Neurodegeneration. The approach uses a two-step process involving antibodies and radioactive tracers to improve targeting of amyloid proteins in the brain. Early tests in animal models suggest the method could reduce radiation exposure and expand applications to other neurological conditions, including brain tumors and inflammation.

These developments come as Alzheimer’s research shifts toward prevention and earlier intervention. Clinical trials such as AHEAD Study are testing whether treatments like lecanemab can slow or stop disease progression before symptoms appear. Researchers say blood biomarkers such as pTau217 could soon play a central role in routine screening, helping clinicians identify at-risk individuals years earlier and opening the door to more effective early treatment strategies.