Predicting Alzheimer’s Risk with a Blood Test
New research indicates that a blood test measuring a single protein could predict a healthy individual’s risk of Alzheimer’s-related cognitive decline up to a decade before symptoms appear. The findings were presented at the Alzheimer’s Association International Conference 2026 in London, England.
Researchers found that older adults with significantly elevated levels of the biomarker p-tau217 had a 78% chance of developing cognitive impairment within 10 years, despite no signs of memory or thinking impairments during preliminary tests.
Currently, almost 7 million Americans live with Alzheimer’s. Without breakthrough treatments, this number is expected to rise to around 13 million by 2050, according to the Alzheimer’s Association.
Potential and Challenges of the Blood Test
Dr. Manisha Parulekar from Hackensack University Medical Center emphasized the transformative potential of a single blood test for Alzheimer’s predisposition in cognitively healthy individuals. Dr. Parulekar stated that the test could facilitate risk assessments in primary care settings, allowing for early and personalized interventions focusing on factors such as blood pressure, sleep, hearing, and physical activity.
This could also expedite recruitment for prevention trials, allowing for testing interventions in the preclinical phase to delay or prevent disease onset. However, Dr. Parulekar warned that positive test results, without the presence of a cure, might lead to psychological distress, anxiety, and anticipatory grief. Concerns were raised about insurance discrimination and unequal access to care.
Responsible implementation must include structured counseling, equitable intervention access, and robust support infrastructure.
Research Insights and Limitations
Researchers analyzed blood samples from nearly 2,700 cognitively healthy adults, averaging 70 years old, collected from six Alzheimer’s research groups and clinical trials. Participants were monitored over approximately five years, with some tracked longer, undergoing standardized tests of memory, thinking, and daily functioning.
Adults with p-tau217 levels more than twice the study average exhibited a 78% risk of cognitive impairment within 10 years and a 38% risk within five years. Moderately elevated levels showed a lower risk but still notable, at approximately 15% over five years and 45% over 10 years.
The blood test proved more predictive than brain scans and genetic testing independently. P-tau217, a modified form of tau protein associated with Alzheimer’s hallmark brain tangles, is linked to amyloid beta levels, making it a valuable marker for disease processes.
Study lead author Rachel F. Buckley noted that elevated p-tau217 levels provide compelling evidence for early dementia risk detection, even in adults without noticeable memory or cognition problems. This test has the potential to recruit patients for trials of treatments targeting cognitive decline prevention.
Despite promising findings, researchers acknowledged that biomarker levels alone cannot fully determine individual risk. Age, genetics, kidney function, obesity, and racial and ethnic backgrounds influence biomarker levels and dementia risk. More diverse populations and extended follow-up periods are required to refine long-term risk estimates.
FDA Approval and Practical Application
The p-tau217 blood test has received FDA clearance for clinical use in the U.S. In May 2025, the FDA approved the Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio, manufactured by Fujirebio, marking the first diagnostic blood test to support Alzheimer’s disease diagnosis.
Newsweek has reached out to the study’s authors for further details.