FDA greenlights first-of-its-kind blood test for Alzheimer's disease: How does it work?

The US Food and Drug Administration (FDA) has granted marketing clearance for a new blood test designed to assist in the diagnosis of Alzheimer’s disease, marking it as the first test approved in the United States for the early detection of this condition.


How does the blood test work?

Named the Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio, this test is intended for adults aged 55 and older who exhibit signs and symptoms of Alzheimer’s. The FDA announced this development on a Friday, highlighting the significance of the test that analyzes two specific proteins in blood plasma: pTau217 and beta-amyloid 1-42. The ratio of these proteins is known to correlate with the presence or absence of amyloid plaques in the brain, which are characteristic markers of Alzheimer's disease, although the test does not directly measure amyloid levels.



Currently, there is no singular test for diagnosing Alzheimer’s disease. Physicians typically utilize a comprehensive approach that includes an evaluation of medical history, neurological exams, cognitive and functional assessments, brain imaging, spinal fluid analysis, and, more recently, blood tests. The results from this newly approved blood test will need to be interpreted alongside other clinical information pertaining to the patient.


FDA Commissioner Dr. Martin Makary emphasized the profound impact of Alzheimer’s disease on the population, noting that it affects more individuals than breast and prostate cancer combined. He pointed out that approximately 10% of people aged 65 and older are living with Alzheimer’s, a figure expected to double by 2050. Dr. Makary expressed optimism that innovative medical products, like this blood test, will significantly benefit patients.


A new hope:

Developed by Fujirebio Diagnostics Inc., a biotechnology company based in Pennsylvania, the new blood test aims to improve access to Alzheimer’s detection and lessen the reliance on positron emission tomography (PET) scans. PET scans can reveal the presence of amyloid plaques in the brain, but they are often costly, sometimes amounting to thousands of dollars without insurance coverage.


The FDA assessed clinical trial data involving plasma samples from 499 cognitively impaired adults. The study compared the blood test results with findings from PET scans or cerebrospinal fluid analysis, such as results from spinal taps. According to the FDA, the data demonstrated that 91.7% of the adults with positive blood test outcomes had confirmed amyloid plaques via their PET scans or cerebrospinal fluid tests, while 97.3% of those with negative blood test results also had negative outcomes in their PET scans or cerebrospinal fluid tests.


The agency cautioned that the main risks associated with this blood test involve the potential for false-positive or false-negative results.

The new era:

A "new era" in Alzheimer’s research is emerging, highlighted by recent advancements in diagnostic methods. Dr. Richard Isaacson, a preventive neurologist and pioneer in Alzheimer's prevention, has been utilizing an FDA-cleared blood test in his research for several years. This test helps determine whether individuals experiencing memory loss may be suffering from Alzheimer’s disease. According to Isaacson, this blood test serves as a simpler and more cost-effective alternative to traditional diagnostic methods, such as PET scans or spinal taps.


While the FDA's approval represents significant progress, Isaacson cautions that further research is essential to clarify how the results of this blood test should be interpreted and applied in clinical settings. He emphasizes the need for enhanced education surrounding the implications of the test results, noting that their meaning can vary based on individual risk factors and symptoms.


Fujirebio Diagnostics developed this blood test to facilitate early detection of Alzheimer’s disease, which is crucial for timely intervention. Monte Wiltse, the company's president and CEO, stated that accurate, early diagnosis could drive the creation of new drug therapies, especially given the increasing prevalence of Alzheimer’s disease associated with global population aging.


Statistics indicate that over 40% of individuals aged 55 and older in the United States are expected to develop dementia in their later years. Importantly, amyloid deposits may accumulate in the brain years before symptoms appear, suggesting that early detection could enable proactive measures to slow the disease's progression, including preventive treatments.


Dr. Maria Carrillo, chief science officer at the Alzheimer’s Association, expressed optimism that this recent FDA approval will make accurate diagnoses more accessible. Although several lab-developed tests exist to identify blood-based biomarkers linked to Alzheimer’s, the Fujirebio test is the first to gain FDA clearance, marking a milestone in the field.


Carrillo noted that blood-based biomarkers are transforming our understanding and identification of Alzheimer’s disease. However, there remain critical considerations for healthcare professionals regarding who should be tested and when.


Dr. Howard Fillit, co-founder of the Alzheimer’s Drug Discovery Foundation, remarked on the significance of being able to diagnose Alzheimer’s more readily with a simple blood test—comparable to cholesterol testing. He believes this innovation illustrates a new era in Alzheimer’s research, where advancements in science and technology are leading to more accessible and effective diagnostic tools.

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