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Blood test that identifies risk of Alzheimer’s disease shown to be highly accurate in large study

Researchers from Washington University School of Medicine in St. Louis have developed a highly reliable blood test for identifying Alzheimer’s disease, which uses the biomarkers amyloid beta proteins Aβ42 and Aβ40. (Image: Dr. Randall J. Bateman in his lab. Credit: Matt Miller/Washington University)

In a large study involving hundreds of patients with various demographics, a blood test developed at Washington University School of Medicine in St. Louis proved to be remarkably accurate in identifying early signs of Alzheimer’s disease, supporting the suggestion that the test should be considered for routine screening procedures.

Senior author Randall J. Bateman, MD, a professor of neurology, stated, “Our study shows that the blood test provides a robust measure for detecting amyloid plaques associated with Alzheimer’s disease, even among patients not yet experiencing cognitive declines.”

The blood test, developed by Bateman and his team, determines if amyloid plaques have begun to form in the brain by comparing the amounts of the amyloid beta proteins Aβ42 and Aβ40 in the blood.

“A blood test for Alzheimer’s provides a huge boost for Alzheimer’s research and diagnosis, drastically cutting the time and cost of identifying patients for clinical trials and spurring the development of new treatment options,” Bateman said. “As new drugs become available, a blood test could determine who might benefit from treatment, including those at very early stages of the disease.”

According to this study, prescreening with the $500 blood test could cut the cost and time required to enroll individuals in PET scan clinical trials by 50%. According to the study, solely screening with blood tests could be done in under six months and could reduce costs by tenfold or even more.

Even when conducted in multiple laboratories using different methods and in different cohorts spanning three continents, the blood test remained extremely accurate, according to the study.

Among all three trials, the Aβ42/Aβ40 blood test, which uses a high-precision immunoprecipitation mass spectrometry technology developed at Washington University, provided very reliable and timely results in both the cognitively impaired and unimpaired groups.

“These results suggest the test can be useful in identifying nonimpaired patients who may be at risk for future dementia, offering them the opportunity to get enrolled in clinical trials when early intervention has the potential to do the most good,” Bateman said. “A negative test result also could help doctors rule out Alzheimer’s in patients whose impairments may be related to some other health issue, disease or medication.”


The study was published in Neurology on February 15th, 2022.

Abstract. In the combined cohort of 465 participants, plasma Aβ42/Aβ40 had good concordance with amyloid PET status (receiver operating characteristic area under the curve [AUC] 0.84, 95% confidence interval [CI] 0.80–0.87); concordance improved with the inclusion of APOE ε4 carrier status (AUC 0.88, 95% CI 0.85–0.91). The AUC of plasma Aβ42/Aβ40 with CSF amyloid status was 0.85 (95% CI 0.78–0.91) and improved to 0.93 (95% CI 0.89–0.97) with APOE ε4 status. These findings were consistent across the 3 cohorts, despite differences in protocols. The assay performed similarly in both cognitively unimpaired and impaired individuals. Plasma Aβ42/Aβ40 is a robust measure for detecting amyloid plaques and can be utilized to aid in the diagnosis of AD, identify those at risk for future dementia due to AD, and improve the diversity of populations enrolled in AD research and clinical trials.

Yan Li, Suzanne E. Schindler, James G. Bollinger, Vitaliy Ovod, Kwasi G. Mawuenyega, Michael W. Weiner, Leslie M. Shaw, Colin L. Masters, Christopher J. Fowler, John Q. Trojanowski, Magdalena Korecka, Ralph N. Martins, Shorena Janelidze, Oskar Hansson, Randall J. Bateman; Validation of Plasma Amyloid-β 42/40 for Detecting Alzheimer Disease Amyloid Plaques, Neurology Feb 2022, 98 (7) e688-e699; DOI: 10.1212/WNL.0000000000013211

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