• Posted October 15, 2025

FDA Clears New Blood Test to Help Rule Out Alzheimer’s Disease

The U.S. Food and Drug Administration (FDA) has cleared another blood test that could help doctors identify whether a patient’s memory problems are likely caused by Alzheimer’s disease.

The new test, called Elecsys pTau181, was developed by Roche Diagnostics in partnership with Eli Lilly. It’s designed for adults 55 and older who are showing early signs of cognitive decline.

“By bringing Alzheimer’s blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys,” Brad Moore, president and CEO of Roche Diagnostics North America, told CNN.

The Elecsys test measures levels of pTau181, a protein found in blood plasma. Higher levels of this protein are linked to Alzheimer’s and other brain diseases.

In a study involving 312 people, the test correctly ruled out Alzheimer’s disease 97.9% of the time, according to Roche.

“When the test result is negative, there’s a very high likelihood the person does not have Alzheimer’s-related pathology," said Laura Parnas, director of medical and scientific affairs at Roche Diagnostics.

“However," she added in a CNN report, "It’s important to note that for patients with a positive result, further clinical investigations and confirmatory testing for the amyloid pathology is needed for the final diagnosis of Alzheimer’s."

The Elecsys pTau181 test is the second blood test cleared by the FDA this year for use in Alzheimer’s evaluation. In May, the agency approved Fujirebio’s Lumipulse test, which detects a different set of proteins associated with the disease.

Experts predict that multiple testing options could improve how doctors assess brain health.

Having access to different blood-based tests that measure different biomarkers can help inform and provide a broader understanding of someone’s brain health when testing for early Alzheimer’s disease, Dr. Richard Isaacson, a preventive neurologist and Alzheimer’s researcher, told CNN.

“To more accurately stage disease and track progression over time, I never order one single test. I only order a panel of tests. We’re not at the time yet where one marker is the ‘be all and end all.’ It’s more complicated than that,” he said. “While there are now resources available to learn about Alzheimer’s risk factors and what these new blood tests might mean, these are still early days.”

Experts say these new tests are exciting, but doctors still need to be careful about how they use and interpret the results.

“We have to be very cautious with mass adoption of these blood tests because of the potential false positives,” Isaacson said. “The medical field is still learning how to use these tests and how to apply these test results in clinical practice.”

Still, Alzheimer’s experts see the approval as a major step forward.

“This is another important step toward expanding access to Alzheimer’s disease diagnostic tools,” said Joanne Pike, president and CEO of the Alzheimer’s Association.  

“By using a ‘rule out’ initial tool in the primary care setting, we can help people who are not living with Alzheimer’s get to the root of their cognitive symptoms faster, while ensuring those who may have the disease are referred for appropriate testing, definitive diagnosis and early treatment,” she added.

Roche said the Elecsys test will be available through its existing network of about 4,500 lab instruments across the United States.

More information

The Mayo Clinic has more on Alzheimer's.

SOURCE: CNN, Oct. 13, 2025