In an effort to help improve the early diagnosis of Alzheimer’s disease, the U.S. FDA has recently cleared the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio made by Fujirebio Diagnostics, Inc., as the first blood test to help diagnose the condition.

Despite all these tools, it can be hard to diagnose Alzheimer’s disease, especially at its earliest stage .

An Alzheimer’s diagnosis is currently made through an evaluation that includes a person’s medical history, cognitive assessment, PET or MRI brain imaging, and laboratory tests to check for the presence of the proteins amyloid-beta and tau in a sample of cerebrospinal fluid (CSF) .

Like all diseases, the sooner Alzheimer’s disease is diagnosed, the better the outcome. This is partially because medications available for the condition aim to treat symptoms and potentially slow the progression of the disease.

Researchers estimate that about 32 million people globally live with a type of dementia called Alzheimer’s disease , with the number of dementia cases expected to triple by 2050 .

“These clumps, called plaques, interfere with communication between the neurons, like blocking pathways in the library. Tau is normally like a librarian, helping to keep the bookshelves (internal neuron structure) stable and organized. In Alzheimer’s, tau becomes twisted and tangled. These tangles disrupt the transport of nutrients and other essential materials within the neurons, eventually leading to their death,” she said.

“Think of beta-amyloid as sticky notes that clump together between the bookshelves (outside the neurons),” Parulekar continued.

“Imagine your brain is like an organized library, with information neatly stored on shelves ( neurons ),” Manisha Parulekar, MD, FACP, AGSF, CMD , director of the Division of Geriatrics at Hackensack University Medical Center and co-director of the Center for Memory Loss and Brain Health at Hackensack University Medical Center in New Jersey explained to Medical News Today. “In Alzheimer’s disease, two troublesome proteins, beta-amyloid and tau, disrupt this organization, making it hard to access the information.”

According to the FDA’s press release , the Lumipulse blood test works by measuring the amount of pTau 217 and beta-amyloid 1-42 in the plasma of the blood. The concentration ratio of the two proteins is used to determine the presence or absence of amyloid plaques in the brain, which is considered a hallmark of Alzheimer’s disease.

“Based on the scientific data provided by the company, only 20% of patients would require additional invasive and costly tests, such as lumbar punctures or PET scans, to confirm the diagnosis. This is a significant improvement, as it allows the majority of patients to receive a preliminary evaluation with minimal discomfort and expense, fostering early detection and intervention,” Gliebus explained.

“By relying on a simple blood sample, this test makes it more accessible to a broader population, facilitating earlier diagnosis and enabling timely interventions that could help manage the progression of the disease. This new test has the potential to change how we diagnose Alzheimer’s disease by streamlining the process and reducing the need for more invasive procedures.” — Gediminas Gliebus, MD

Gediminas Gliebus, MD , director of cognitive and behavioral neurology at Marcus Neuroscience Institute, a part of Baptist Health South Florida, told MNT having a test requiring a blood sample instead of a CSF sample significantly simplifies the testing process, eliminating the need for invasive and costly procedures like lumbar punctures, which can deter some patients from seeking evaluation.

Up until now, the main laboratory test to check levels of amyloid-beta and tau proteins was by examining a sample of a person’s cerebrospinal fluid (CSF). The sample is taken through a lumbar puncture — also known as a spinal tap — where a needle is inserted into a person’s lower spine.

As part of their approval announcement, the FDA stated risks associated with the Lumipulse blood test include both false positive and negative results.

For that reason, all of the experts we spoke with agree that while this new test is a promising diagnostic tool, it is not the only tool that should be used and more research is still needed.

“This test has potential for use in pre-screening participants in clinical trials for early stages of Alzheimer’s disease, however, its application in primary care settings is not yet fully understood, and further research is needed before it is used as a screening tool for the general population,” Bhavana Patel, DO, assistant professor of neurology at the University of Florida explained to MNT.

Things to keep in mind about the test “As with many tests, false positives and false negatives can occur. Therefore, this test should be done in the setting of cognitive symptoms and with a specialist who can accurately interpret and counsel on the results.”

“My first response to this blood test is concern (that) primary care physicians are going to diagnose patients with Alzheimer’s dementia from a blood test who have no memory loss or risk factors for dementia,” added Clifford Segil, DO a neurologist in private practice in Santa Monica, CA, and on staff at Providence St John’s Health Center.

“And tests like this, which were not approved by the typical rigorous FDA pathway, but rather through an abbreviated process via the FDA’s ‘ Breakthrough Pathway ,’ which cause me concern countless people are going to be told they have dementia per a blood test when they do not have dementia,” he said.