Should You Get a Blood Test for Alzheimer’s?

Blood test for Alzheimer’s

There are two types of tests that check for recognized markers of Alzheimer’s disease. One that measures levels of beta -amyloid proteins and another that measures phosphorylated tau (p-tau) proteins.

“Some of these blood-based tests work better than others,” said Lynn M. Bekris, Ph.D., principal investigator at the Cleveland Clinic’s Lynn Bekris Lab. “The new blood tests for p-tau biomarkers are very promising.”

Earlier this year, in a groundbreaking study, researchers accurately tested for elevated levels of p-tau, a hallmark for Alzheimer’s, from a regular blood test.

This is notable for a few reasons. First, the test results were as accurate as the current FDA-approved spinal tap fluid test and brain scan used to identify and help diagnose Alzheimer’s disease.

This means a blood test may be able to replace the more invasive procedure without compromising results. And blood tests are easier to get than brain scans and spinal taps.

Perhaps the most important detail of the study is that it showed the ability to measure changes in protein levels years before symptoms show. This offers hope that testing for Alzheimer’s without symptoms is possible and may one day be part of a routine screening, like you would have for high cholesterol or diabetes.

The study tested for a specific form of p-tau called p-tau217. Bekris noted that there are many forms of p-tau found in the blood, but p-tau217 is a promising biomarker because it’s very high in people with Alzheimer’s disease. “One particular p-tau217 test has received FDA approval and will likely be available soon commercially,” Bekris said.

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Tests for p-tau are still used only in research at this point, but currently you can get a blood test for beta amyloid proteins as a risk assessment tool for Alzheimer’s. To get the test, you need to have certain risk factors and to talk to your healthcare provider about the pros and cons. If the test is right for you, they can write you a prescription.

Should you get a blood test for Alzheimer’s disease?

It’s important to note that the test is meant to show potential risk and does not diagnose Alzheimer’s. It’s also not approved by the FDA and is not currently covered by health insurance. In addition, some experts have raised questions about the accuracy of the beta amyloid protein test, noting that it could result in false positives, which could cause unnecessary anxiety for people. Bekris noted that testing the blood or fluid for p-tau is more accurate than measuring the levels of beta amyloid in blood but false positives are still possible. The hope is that blood tests can start out as a tool that leads to more evaluation.

Currently, a diagnosis for Alzheimer’s comes from multiple results from brain imaging, memory tests and biomarker tests — among other factors.

Bekris said the multiple diagnostic tests are better together than alone. “This more detailed evaluation will rule out or rule in Alzheimer's disease with the highest accuracy and is needed before the type of Alzheimer's treatment is selected by both patient and their doctor,” she said.

This year has seen some significant advancements in research. But there’s still no cure for Alzheimer’s. We’re ready for more options, treatments and solutions for this devastating brain disease.