A new test developed at Washington University School of Medicine in St. Louis has proven high accuracy in detecting early signs of Alzheimer’s disease in a study that involved 465 participants. The study was published in the journal Neurology.
The research team behind the study aimed to determine the diagnostic accuracy of a plasma Aβ42/Aβ40 assay in classifying amyloid PET status. It included 465 plasma samples that were obtained from 3 large Alzheimer disease (AD) research cohorts in the United States, Australia and Sweden.
The plasma Aβ42/Aβ40 was measured using high precision immunoprecipitation mass spectrometry (IPMS) assay and was compared to the reference standard of amyloid PET and CSF Aβ42/Aβ40.
Plasma Aβ42 and Aβ40 as measured by conventional techniques like ELISA have relatively high variance and typically perform poorly in distinguishing amyloid-positive and amyloid-negative individuals. That is why researchers used a different method, IPMS.
The blood test was assumed to have a sensitivity of 0.80 and specificity of 0.83 in cognitively unimpaired participants. The study showed that the blood test remains highly accurate, even when performed in different labs following different protocols, and in different cohorts across 3 continents.
When blood amyloid levels were combined with another major Alzheimer’s risk factor – the presence of the genetic variant APOE4 – the accuracy of the blood test was 88% when compared to brain imaging and 93% when compared to spinal tap.
According to the researchers their 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. This study could provide a boost for AD research and diagnosis, while also cutting the time and cost of identifying patients for clinical trials and could also lead to the development of new treatment options.
Li Y, Schindler SE, Bollinger JG, Ovod V, Mawuenyega KG, Weiner MW, Leslie SM, Masters CL, Fowler, CJ, Trojanowski JQ, Korecka M, Martins RN, Janelidze S, Hansson O, Bateman R. Validation of Plasma Amyloid-β 42/40 for Detecting Alzheimer Disease Amyloid Plaques. Neurology. Dec. 14, 2021. DOI:https://doi.org/10.1212/WNL.0000000000013211.
Gerry Everding. (2022, Feb 22). Blood test for Alzheimer’s highly accurate in large, international study. Washington University School of Medicine in St. Louis. Retrieved from: https://medicine.wustl.edu/news/blood-test-for-alzheimers-highly-accurate-in-large-international-study/