The US Food and Drug Administration has given marketing clearance to blood tests to help diagnose Alzheimer’s disease, making it the first test to get a sign-off to help detect diseases in the US early.
The test, called the Lumipulse G PTAU217/ß-amyloid 1-42 plasma ratio, is intended for adults over the age of 55 who show signs and symptoms of Alzheimer’s disease, the FDA announced Friday.
It works by measuring two proteins in plasma: PTAU217 and beta amyloid 1-42. The ratio of these proteins tends to correlate with the development or absence of amyloid plaque in the brain, one of the characteristics of Alzheimer’s disease. This test can show its presence rather than directly measuring amyloid.
However, no current single test remains to diagnose Alzheimer’s disease. Doctors rely primarily on a variety of tools to diagnose their condition, including medical history, neurological examinations, cognitive and functional assessments, brain imaging, spinal fluid analysis, and more recently blood tests.
The FDA said the results of newly cleared blood tests should be evaluated in conjunction with other clinical information from the patients.
“Alzheimer’s disease affects more people than breast and prostate cancer combined,” FDA commissioner Dr. Martin McCurry said in a announcement Friday. “We know that 10% of people over 65 have Alzheimer’s disease and that by 2050 we expect that numbers will double, so we hope that new medical products like this will help our patients.”
According to the FDA, a new blood test developed by Pennsylvania-based Biotechnology Company Fujirebio Diagnostics Inc. will help increase access to disease detection for Alzheimer’s disease and reduce reliance on positron drainage tomography or PET scans.
The FDA said it reviewed clinical trial data on new blood tests, including plasma samples collected from 499 adults with cognitive impairment. Samples were evaluated using blood tests, and results were compared with results from individual tests using patients’ PET scans or cerebrospinal fluid samples, such as spinal taps.
Data showed that 91.7% of adults with positive results using blood tests were in the presence of amyloid plaque confirmed by PET scan or cerebrospinal fluid test, and 97.3% of people with negative results had negative amyloid PET scan or cerebrospinal fluid test results according to the FDA.
The agency added that the risks associated with blood tests are primarily the risk of false positive or false negative test results.
Dr. Richard Isaacson, a preventive neurologist who founded one of the first Alzheimer’s disease prevention clinics in the United States, said he has been using the blood test for many years to conduct research and praises the FDA’s clearance.
“It can make it more clear if someone experiencing memory loss may have Alzheimer’s disease, and they can take this test as a screening test,” says Isaacson, director of research at the Institute for Neurodegenerative Diseases in Florida. Compared to costly PET scans and spine taps, “This is a much simpler screening test with reasonable accuracy to tell doctors that people with cognitive decline actually have symptoms caused by Alzheimer’s disease.”
However, Isaacson warned that while FDA clearance is a “significant step forward” for the field, more research is needed to know how blood test results should be interpreted and used to make clinical decisions.
“I think the next step as a field is to educate people about what these tests mean, what they don’t use, who should use it,” he said. “Because it means different things from different people depending on the risk factors and whether they have symptoms, so it’s too early.”
Fujirebio Diagnostics designed blood tests to detect Alzheimer’s disease early and early when the intervention is more effective, President and CEO Monte Wiltse said in a news release last year that he submitted the tests to the FDA.
“Early and accurate diagnosis will promote the development of new drug therapies, which is urgently necessary as the prevalence of AD, which is rapidly aging worldwide, increases,” Wiltse said.
It is estimated that more than two in five people over the age of 55 in the United States (approximately 42%) develop dementia in later years.
However, in some cases, amyloid deposits may begin to accumulate in the brain decades before the symptoms of Alzheimer’s disease begin. Early detection of these amyloid plaques can open the door to taking measures to slow the progression of the disease, such as initiating preventive treatment with drugs.
“For too long, Americans have struggled to get simple and accurate diagnoses. We hope that today’s actions by the FDA will make it easier for more individuals to get an accurate diagnosis early,” said Dr. Maria Carrillo, Chief Scientific Officer and Medical Officer of the Alzheimer’s Disease Association.
According to the Alzheimer’s Disease Association and experimental tests, there are various laboratory-developed tests on the market that can be used to detect blood-based biomarkers associated with Alzheimer’s Disease. However, the Fujirebio diagnostic test is the first test to be cleared by the FDA.
“Blood-based biomarkers are reconstructing the way Alzheimer’s disease is identified and understood,” Carrillo said. “At the same time, there are important questions that health professionals should consider, especially who should test it?”
For now, FDA clearance “marks a major milestone,” said Dr. Howard Phillitt, co-founder and chief science officer of the Alzheimer’s Drug Discovery Foundation.
“The ability to previously diagnose Alzheimer’s disease with simple blood tests, like cholesterol, is a game-changer, allowing more patients to receive treatment options that may significantly slow or even prevent the disease,” Fillit said in an email Friday. “This is a clear example of a new era of research in Alzheimer’s disease, where innovation, science and technology are coming together to develop more accessible, affordable, scalable tools and pave the way for additional regulatory approval of diagnostic tools.”