The FDA has cleared the first blood test to diagnose
Alzheimer’s disease. Bowery Image Group Inc./Stocksy
- The
earlier Alzheimer’s disease can be diagnosed, the better the outcomes;
however, it can be hard to diagnose the disease in its earliest stages.
- The
United States Food and Drug Administration recently cleared the first
blood test to help diagnose Alzheimer’s disease.
- The
new test measures the amount of proteins amyloid-beta and tau in the
blood, and is less invasive than the currently used spinal tap to measure
levels of these proteins in cerebrospinal fluid.
Researchers
estimate that about 32 million peopleTrusted Source globally live with a type of dementia called Alzheimer’s disease, with the number of dementia cases expected to triple by 2050Trusted Source.
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.
An
Alzheimer’s diagnosisTrusted Source 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 tauTrusted Source in a sample of cerebrospinal fluid (CSF).
Despite
all these tools, it can be hard to diagnose Alzheimer’s disease, especially at
its earliest stageTrusted Source.
In
an effort to help improve the early diagnosis of Alzheimer’s disease, the U.S.
FDA has recently clearedTrusted Source 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.
According
to the FDA’s press releaseTrusted Source, the Lumipulse blood test works by measuring the amount of pTau 217 and beta-amyloid 1-42Trusted Source 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.
“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.”
“Think
of beta-amyloid as sticky notes that clump together between the bookshelves
(outside the neurons),” Parulekar continued.
“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.
“In simple terms, this blood test helps identify the
‘culprits’ responsible for Alzheimer’s damage, allowing for earlier diagnosis,
better disease management, and faster development of effective treatments.”
— Manisha Parulekar, MD, FACP, AGSF, CMD
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 punctureTrusted Source —
also known as a spinal tap — where a needle is inserted into a person’s lower
spine.
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.
“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
“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.
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.”
— Bhavana Patel, DO,
“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 PathwayTrusted Source,’ 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.
“Neurologists
in clinical practice have found similar tau and amyloid biomarkers to have a
high percentage of false positives in clinical practice and do not rely only on
a blood test to diagnose a family member or you with dementia,” Segil
told MNT. “Neurologists are unlikely to use these tests, which
will be used by primary care physicians. If you do get a positive result from a
blood tau or amyloid test, please be evaluated by a neurologist to determine if
they have any clinical significance.”
With
some questions still to be answered regarding the Lumipulse blood test, many
experts expressed their hope that it will provide more assistance in the early
diagnosis of Alzheimer’s disease.
“This
is an exciting time in the field, as we now have a noninvasive, easily
accessible test that can help identify Alzheimer’s disease in individuals
experiencing memory changes,” Patel said. “Having an easily accessible blood
test will allow for an earlier diagnosis in those with cognitive changes and
serve as an opportunity for participation in clinical trials and receive
treatments that may impact disease progression.”
“I
was genuinely excited to hear about the FDA’s [clearing] of this blood test, as
it represents a significant advancement in simplifying the evaluation of
patients who present with symptoms that might suggest Alzheimer’s disease,”
Gliebus commented. “This test offers a less invasive and more accessible way to
evaluate the condition, potentially transforming how we approach early
diagnosis and patient care.”
LOWER COST, LESS INVASIVE
“The less invasive nature of a blood test will likely
encourage more people experiencing mild cognitive impairment or early symptoms
to seek testing. Earlier diagnosis is crucial for maximizing the effectiveness
of current and future treatments. The simplicity and lower cost of blood tests
compared to PET scans or spinal taps will make testing more accessible to wider
populations, including those in underserved communities or without easy access
to specialized medical centers. This could lead to earlier diagnosis for
individuals who might otherwise go undiagnosed for years.”
— Manisha Parulekar, MD, FACP, AGSF, CMD
“We
do have to follow appropriate steps in the diagnosis and make sure to use this
as a diagnostic tool — this is not a screening test. It’s a tool that holds
promise — its true impact will depend on how it’s integrated into clinical
practice,” Parulekar added.