Blood test could find Alzheimer’s disease before symptoms appear

In the journals

Researchers are close to finding early cancer with a blood test. They may soon do the same with Alzheimer's disease. A new blood test called p-tau217 has shown great promise in diagnosing people with the disease, according to findings published online July 28, 2020, by JAMA.

The test looks for a specific type of tau protein in the blood. In people with Alzheimer's, tau protein in the brain forms tangles. Accumulation of tau protein tangles along with beta-amyloid deposits is thought to play a key role in how the disease develops.

For this study, the researchers combined the results of three separate studies that used the p-tau217 blood test. One study looked at brain autopsies. Another examined people with and without a clinical diagnosis of Alzheimer's. The third compared people who have a genetic mutation highly associated with Alzheimer's to those without the mutation. Based on blood samples taken from a total of 1,402 people, the blood test was highly accurate in determining whether cognitive changes and memory loss were likely due to the disease. It also accurately identified Alzheimer's before dementia occurred.

More studies are needed to verify the findings. While there is no cure for Alzheimer's, the test could help identify the disease as early as 20 years before cognitive issues appear, says the researchers.

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