Scientists Get Closer to Blood Test for Alzheimer’s Disease

US News & World Report:

New study results are boosting hopes that there soon may be a simple, reliable way to help family doctors diagnose the most common form of dementia.

An experimental blood test was highly accurate at distinguishing people with Alzheimer’s disease from those without it in several studies, boosting hopes that there soon may be a simple way to help diagnose this most common form of dementia.

Developing such a test has been a long-sought goal, and scientists warn that the new approach still needs more validation and is not yet ready for wide use.

But Tuesday’s results suggest they’re on the right track. The testing identified people with Alzheimer’s vs. no dementia or other types of it with accuracy ranging from 89% to 98%.

“That’s pretty good. We’ve never seen that” much precision in previous efforts, said Maria Carrillo, the Alzheimer’s Association’s chief science officer.

Dr. Eliezer Masliah, neuroscience chief at the U.S. National Institute on Aging, agreed.

“The data looks very encouraging,” he said. The new testing “appears to be even more sensitive and more reliable” than earlier methods, but it needs to be tried in larger, more diverse populations, he said.

Results were discussed at the Alzheimer’s Association International Conference taking place online because of the coronavirus pandemic. Some results also were published in the Journal of the American Medical Association.

More than 5 million people in the United States and many more worldwide have Alzheimer’s. Current drugs only temporarily ease symptoms and do not slow mental decline.

The disease is usually diagnosed through tests of memory and thinking skills, but that’s very imprecise and usually involves a referral to a neurologist. More reliable methods such as spinal fluid tests and brain scans are invasive or expensive, so a simple blood test that could be done in a family doctor’s office would be a big advance.

Last year, scientists reported encouraging results from experimental blood tests that measure abnormal versions of amyloid, one of two proteins that build up and damage Alzheimer’s patients’ brains. The new work focuses on the other protein — tau — and finds that one form of it called p-tau217 is a more reliable indicator. Several companies and universities have developed experimental p-tau217 tests.

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