Blood Test May Predict Amyloid Deposits in Brain, Potentially Indicating Alzheimer’s Disease
A number of research projects are underway to develop a sensitive blood test that could help screen people for Alzheimer’s disease in a less-invasive and costly way than current imaging and biomarker tests.
Researchers recently reported an advance for their method of detecting amyloid protein in blood (Schindler et al., 2019) and are validating the method by showing an association between blood levels of amyloid and results from conventional biomarker tests for Alzheimer’s.
Using a technique called immunoprecipitation mass spectrometry, researchers developed a precise method for quantifying how much beta-amyloid 42 and beta-amyloid 40 are in a sample of blood. Previous studies have suggested the ratio of these two forms of beta-amyloid may correspond with amyloid in the brain (watch viedo below).
Next, the researchers analyzed the blood of 158 adults (average age, 66), most without dementia symptoms, using their sensitive method, and evaluated them with positron emission tomography (PET) imaging and cerebrospinal fluid tests. Results indicated the ratio of beta-amyloid 42 and beta-amyloid 40 in blood was associated with the detection of amyloid by PET scans and cerebrospinal fluid tests.
Researchers then added other factors to their statistical model to help predict which people would have amyloid deposits with PET imaging. By adding age and APOE genetic status to the blood test results, the model was significantly better at predicting which people would have amyloid detected by PET scans.
Studies are already in progress to further evaluate this method with people who have symptoms of Alzheimer’s disease. Ideally, future studies would use tissue samples from postmortem brains rather than the less-sensitive images of plaques from PET scans to assess the relationship between the ratio of beta-amyloid 42 and beta-amyloid 40 and amyloid plaques in the brain. After more development and validation, this blood test method may help researchers to quickly screen people for eligibility in Alzheimer’s studies.
- Schindler, S.E., Bollinger, J.G., Ovod, V., Mawuenyega, K.G., Gordon, B.A., Holtzman, D.M., … Bateman, R.J. (2019). High-precision plasma β-amyloid 42/40 predicts current and future brain amyloidosis. Neurology, 93(17), e1647-e1659. 2019. https://doi.org/10.1212/WNL.0000000000008081