The new test measures two proteins—pTau217 and β-amyloid 1-42—in the blood and calculates their numerical ratio. The data correlates with the presence or absence of amyloid plaques in the patient's brain, reducing the need for expensive and limited-availability PET scanning. Protein plaques can typically be detected using PET and invasive cerebrospinal fluid analysis. Now, at-risk individuals will have a much simpler method for early diagnosis. The study's findings are published on the Alzheimer's Association website.
According to clinical testing results, 92% of people with positive results had amyloid plaques based on PET scans or cerebrospinal fluid tests. Ninety-seven percent of participants with negative blood tests showed no signs of neurodegeneration based on gold-standard tests.
"This means that the new blood test can reliably predict the presence or absence of Alzheimer's disease amyloid pathology at the time of testing in people with cognitive impairment," the authors concluded.
At this stage, the test will be used on people over 55 with early signs of cognitive decline. It will serve as a first-line tool for identifying patients who will undergo a full evaluation to diagnose early-stage Alzheimer's disease.
Previously, other US scientists presented a home test for Alzheimer's disease that uses olfactory perception. It was found that decreased olfactory function in older adults is more likely to indicate neurodegeneration.
