The test is designed to detect amyloid plaques in the brain for patients with symptoms.
The Food and Drug Administration on Friday green-lit a blood test to detect plaques in the brain associated with Alzheimer's disease, providing a less risky and more accessible tool to help diagnose the neurodegenerative condition.
The test, called Lumipulse, measures two proteins found in the blood's plasma to determine whether a patient has amyloid plaques in the brain. Up until now, physicians have mostly used costly, more invasive tests that involve puncturing the lumbar -- known as a spinal tap -- and brain scans that expose patients to radiation to confirm the presence of amyloid. The Lumipulse test takes a simple blood draw.
"Today's clearance is an important step for Alzheimer's disease diagnosis, making it easier and potentially more accessible for U.S. patients earlier in the disease," Michelle Tarver, director of the FDA's Center for Devices and Radiological Health, said in a statement.
Competition is ramping up among companies developing next-generation tests to diagnose Alzheimer's, which afflicts nearly 7 million Americans. Lumipulse is made by Fujirebio Diagnostics, part of Japan's H.U. Group. Privately held C2N Diagnostics and Quanterix are also developing blood-based tests for Alzheimer's.
It wasn't clear how much the test will cost, and H.U. Group didn't immediately respond to a request for comment.
"The idea that there's a blood test for Alzheimer's disease is unfathomable to me. It's just an incredible advance," said Howard Fillit, a geriatrician and chief science officer of the Alzheimer's Drug Discovery Foundation, which financially supported Fujirebio's effort.
Patients who are experiencing memory problems generally begin by seeing a primary care physician, he said. Now those doctors could order a blood test and, if positive, refer a patient to a neurologist. "I think it's going to dramatically change clinical care," he said.
There are some laboratory-developed blood tests to detect Alzheimer's already on the market; the FDA does not review most lab tests before patients use them. But Fujirebio's product is the first blood test to receive sign-off from the agency. Blood test have been used in clinical trials and are now increasingly used by specialists in clinical settings, according to the Alzheimer's Association.
"Today marks another important step in Alzheimer's disease diagnosis," Maria C. Carrillo, the association's chief science officer, said in a statement. "For too long Americans have struggled to get a simple and accurate diagnosis, with today's action by the FDA we are hopeful it will be easier for more individuals to receive an accurate diagnosis earlier."
The newly cleared test is intended for patients at specialized care centers who have signs and symptoms of cognitive decline, according to the FDA. The agency said the results should be interpreted along with other patient clinical information.
If a person is showing signs of cognitive decline, they should consult a physician about first undergoing memory and neuropsychology tests, according to Brian Balin, a professor of neuroscience and experimental neuropathology at the Philadelphia College of Osteopathic Medicine. The blood test should not be used for those who do not have signs of cognitive decline because of the risk of a false result, he said.
"You would have to see some level of change there that then would indicate, 'Let's get a blood test,'" he said.
The presence of amyloid plaques, sticky substances in the brain, is a hallmark of Alzheimer's disease -- though the role it plays is a matter of debate among neurologists. The FDA has approved three anti-amyloid drugs since 2021, including Kisunla made by Eli Lilly and Leqembi made by Eisai and Biogen. Clinical trials showed the drugs can modestly slow the disease's progression but not reverse it, and they remain controversial because of their risks and high price tag.
A third anti-amyloid drug, Aduhelm, won approval but was abandoned by Eisai and Biogen after it fizzled commercially.
There is no cure for Alzheimer's disease, and debate over medications to treat the drug have been fraught. The medications have been dogged by complications such as bleeding in the brain.
The FDA cleared Lumipulse for patients at least 55 years old with symptoms of the disease, based on a clinical study of 499 plasma samples from patients with cognitive impairment.
The main risks of the Lumipulse test are false positives and false negatives, the agency said. The study found that 91.7 percent of patients who tested positive for the presence of amyloid were confirmed to have the plaques by brain scans or spinal tap procedures, and 97.3 percent of patients with negative results were similarly confirmed not to have the plaques.