A blood test developed by scientists at the University of Washington assesses whether amyloid plaques have begun to accumulate in the brain based on the ratio of levels of the beta-amyloid proteins Aβ42 and Aβ40 in the blood. It can be used even in those patients not yet experiencing cognitive decline and is an inexpensive and accessible alternative to expensive brain scans and invasive spinal tap, which are currently used to assess the presence and progression of disease in the brain.
A commercial test based on a technique for measuring the ratio of Aβ42 to Aβ40 proteins was certified back in 2020 under the Clinical Laboratory Improvement Amendments (CLIA) program. However, until recently, scientists didn’t know whether small differences in sampling methods, such as drawing blood after fasting or the type of anticoagulant used in blood processing, could have a big impact on its accuracy, producing false negatives or false positives.
To test this, the researchers applied the new assay to blood samples from people participating in ongoing Alzheimer’s disease studies in the United States, Australia and Sweden, each of which uses different protocols for processing blood samples and corresponding brain imaging.
The results of this study confirmed that the Aβ42 to Aβ40 ratio blood test developed at the University of Washington produced very accurate and consistent results for both people with cognitive impairment and healthy individuals in all three studies.
When blood amyloid levels were combined with another important risk factor for Alzheimer’s disease – the presence of the APOE4 genetic variant – the accuracy of the blood test was 88% compared with brain imaging and 93% compared with spinal tap.
The advent of a newly available assay for researching and diagnosing Alzheimer’s disease is now in the arsenal of clinicians, dramatically reducing the time and cost of identifying patients for clinical trials and spurring the development of new treatment options. The analysis can identify who may benefit from treatment, including in the very early stages of the disease, as well as rule out Alzheimer’s disease in patients whose cognitive impairment is related to some other health problem, disease or medication.
Shutterstock/FOTODOM UKRAINE photos were used
