By Becky Streeter
Researchers have recently discovered that combining two blood tests used for diagnosing cognitive decline–plasma phosphorylated tau 217 (p-tau217) and amyloid 42/40 ratio–produces a 90% accuracy rate in determining the presence of Alzheimer’s disease in the brain. As Alzheimer’s can be somewhat tricky to diagnose because its symptoms can mimic other types of cognitive decline, this could be a significant breakthrough for the Alzheimer’s ommunity.
The p-tau217 test can diagnose mild cognitive impairment and early-stage Alzheimer’s. The test measures the level of the tau protein 217 and also identifies if beta-amyloids are present. Tau tangles can be symptoms of other neurological diseases potentially causing memory loss at some point, but amyloid plaques are a key feature of Alzheimer’s that cluster on the memory center of the brain. If the tau protein is elevated but amyloid is not present, it is not Alzheimer’s but an indication of another type of dementia.
Though the p-tau217 test is very promising, combining it with the amyloid 42/40 test increases the accuracy of the results–this is called amyloid probability score. The amyloid 42/40 ratio blood test measures two specific types of proteins that have been linked to Alzheimer’s. Researchers confirmed their results using spinal fluid taps and PET scans, which is currently the only verified way to diagnose Alzheimer’s with certainty. The amyloid probability score was accurate in 90% of the cases in the study of over 1,200 people undergoing treatment for cognitive decline.
These blood tests, once vetted, could have a large impact on diagnosis and treatment for Alzheimer’s. A person’s brain can form amyloid deposits as young as 30 or 40 years old, decades before any symptoms begin. If caught early, people could make lifestyle changes and take preventative measures. Researchers can also conduct new trials to help them learn more about the disease from an earlier standpoint and develop better medications. Additionally, an accurate test will free up services and treatment for those who actually have Alzheimer’s and have not simply been misdiagnosed or missed-diagnosed by the current standards of screening.
Since these blood tests are still being researched, it is unclear if and when they will be made available to the public. The tests need to be verified on a wider scale of study, and then they have to be distributed to physicians who will need to be educated on guidelines and nuances of the test. However, the prospect and potential magnitude of this breakthrough is extremely exciting.
Source: LaMotte, Sandee. “Alzheimer’s blood test catches 90% of early dementia cases, study finds.” CNN. 28 JUL 2024. https://www.cnn.com/2024/07/28/health/alzheimer-blood-test-p-tau-217-wellness/index.html.
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