Key Takeaways
- Blood tests that accurately and reliably detect Alzheimer's
hallmark brain changes signal a shift to simpler, more accurate and
earlier detection and diagnosis, potentially superseding current
methods that are expensive, invasive and not always
accessible.
- A blood test was around 90% accurate in identifying
Alzheimer's disease in patients with cognitive symptoms seen in
primary care and at specialized memory care clinics. In the
research study, primary care physicians were 63% accurate and
specialists were 73% accurate when not using the blood
test.
- Blood tests, once they are confirmed, could enhance
recruitment for Alzheimer's clinical trials and slash wait times
for Alzheimer's disease assessment.
PHILADELPHIA, July 28, 2024 /PRNewswire/ -- As highly
accurate blood tests for Alzheimer's disease are moving closer to
use in physician's offices, new research suggests that they may
revolutionize the accuracy of diagnosis and provide a cleaner,
quicker path to research participation and treatment, according to
data reported today at the Alzheimer's Association International
Conference® (AAIC®) 2024, in Philadelphia and online.
Dementia is often underdiagnosed—and if it is diagnosed by a
clinician, many people nonetheless are unaware or uninformed of
their diagnosis, according to the 2024 Alzheimer's Disease Facts
and Figures report. Blood tests for Alzheimer's are
demonstrating in research that they could significantly improve a
clinician's accuracy and confidence, provide greater accessibility
and a platform for enhanced communication.
Blood tests that show the most promise for identifying
Alzheimer's-related changes in the brain assess phosphorylated tau
(p-tau) protein, an Alzheimer's biomarker that can build up before
patients show signs of cognitive impairment. Increases in the
specific marker p-tau217 over time correlate with worsening
cognition and brain atrophy. The p-tau217 test also predicts the
likelihood of amyloid plaques in the brain, which are another
biomarker for Alzheimer's and the target for recently approved
treatments.
"Blood tests, once they (a) are confirmed in large populations
to be more than 90% accurate and (b) become more widely available,
show promise for improving, and possibly redefining, the clinical
trial recruitment process and the diagnostic work-up for
Alzheimer's," said Maria C.
Carrillo, Ph.D., Alzheimer's Association chief science
officer and medical affairs lead. "While at this time doctors in
primary and secondary care should use a combination of cognitive
and blood or other biomarker testing to diagnose Alzheimer's, blood
tests have the potential to increase the accuracy of early
diagnoses and maximize the opportunity to access Alzheimer's
treatments as early as possible for better outcomes."
When considering use of a blood test, the Alzheimer's
Association Appropriate Use Recommendations for Blood Biomarkers in
Alzheimer's Disease should be carefully followed. To help guide
health care professionals in incorporating blood tests for
Alzheimer's in their clinical practice, the Association has
convened a panel of clinical and subject-matter experts and is
leading the preparation of clinical practice guidelines for the use
of blood biomarkers in Alzheimer's, which will be previewed at AAIC
2024.
Blood Test Can Improve Diagnosis Among Primary Care and
Alzheimer's Disease Specialists
A large study, reported for the first time at AAIC 2024, shows
that blood tests can do a better job of accurately detecting
Alzheimer's than both primary care doctors and specialists who were
using traditional diagnostic methods.
In the study, 1,213 patients were tested with the PrecivityAD2
test (known as "APS2"). It uses a combination of (1) plasma
phosphorylated-tau217 to not-phosphorylated-tau217 ratio (known as
%p-tau217) and (2) the ratio of two types of amyloid (Aβ42/Aβ40),
and it significantly outperformed clinicians in this study.
- Among 698 patients seen at memory clinics, APS2 was around 90%
accurate at identifying Alzheimer's disease while specialists were
73% accurate.
- Among 515 patients seen in primary care, APS2 was also around
90% accurate; primary care physicians were 63% accurate at
identifying Alzheimer's.
Researchers observed that the APS2 test was highly accurate even
in patients with comorbidities, such as kidney disease, which are
common in older patients seen by primary care physicians.
"Notably, these were the results of blood samples that have been
shipped bi-weekly for analysis from primary care units, which is
similar to routine clinical practice," said lead author
Sebastian Palmqvist, M.D., Ph.D., at
Lund University, Lund, Sweden. "These results were especially
impressive considering that older populations in primary care often
have medical conditions that can influence or vary the
concentrations of p-tau217."
"We see this as a major step towards global clinical
implementation of an Alzheimer's blood test," said senior author
Oskar Hansson, M.D., Ph.D., also at
Lund University. "It highlights
the need for Alzheimer's biomarkers in making a correct diagnosis
more of the time. The next steps include establishing clear
guidelines for how an Alzheimer's blood test can be used in
clinical practice, preferably by implementing these tests first in
specialist care and then in primary care. This work is currently
ongoing."
The research reported at AAIC is funded in part by the
Alzheimer's Association, and is simultaneously published in the
Journal of the American Medical Association.
Research Shows Blood Tests Could Identify Cognitively
Unimpaired People for Clinical Trials
Including people at earlier stages of Alzheimer's in clinical
trials could potentially help identify treatments that may be
effective when symptoms are mild or absent. A study reported at
AAIC 2024 found that p-tau217 blood tests could provide a simple
and accurate selection tool for identifying cognitively unimpaired
patients who likely have amyloid-beta plaques in their brains.
The researchers analyzed samples from 2,718 cognitively
unimpaired participants across 10 different studies who had
available plasma p-tau217 and amyloid-beta PET imaging or CSF
samples. They found that plasma p-tau217 can positively predict
(with a range of 79-86%) the likelihood that a cognitively
unimpaired person would also test positive for amyloid-beta
pathology on an amyloid PET scan or CSF biomarker. Adding the
results from the amyloid-beta CSF test or an amyloid beta PET scan
to the analysis after a positive blood sample improves the positive
prediction to 90% or above, and thereby confidence in the presence
of amyloid in the brain using a plasma p-tau217 test.
"If these numbers hold up and are replicated and confirmed by
other independent labs, this approach may reduce the need for
lumbar punctures and PET scans for Alzheimer's diagnosis by 80 or
even 90 percent," said Gemma Salvadó, Ph.D., lead author of the
study and an associate researcher at Lund University. "Our results support that
plasma p-tau217 positivity alone may be sufficient as a selection
of cognitively unimpaired, amyloid-positive participants for many
clinical trials."
Blood Tests Could Drastically Reduce Wait Times for
Alzheimer's Diagnosis and Treatment
Approved Alzheimer's treatments are indicated for people with
mild cognitive impairment due to Alzheimer's or mild Alzheimer's
dementia, and they must have confirmed amyloid-beta biology in the
brain. Therefore, it's important to identify people who might
benefit as early in the course of the disease as possible. Right
now, there are often lengthy wait times to complete comprehensive
testing for an Alzheimer's diagnosis due to the limited number of
Alzheimer's specialists, and variable and often inequitable
access to PET imaging or the expertise required for CSF
analysis.
Research reported at AAIC 2024 suggests that using
high-performing blood tests in primary care could identify
potential Alzheimer's patients much earlier so specialists can
determine if they are eligible for new treatments.
The researchers used a well-established forecasting model to
predict wait times for people eligible for treatment, accounting
for both the limited number of Alzheimer's disease specialists and
the growing older population. The model included the projected U.S.
population of people 55 and older from 2023 to 2032 and compared
two scenarios. The first was that primary care clinicians would
decide whether or not to refer a patient to an Alzheimer's disease
specialist based on the results of a brief cognitive test. The
second was that they would also factor in the results of a
high-performance blood test and assume that a blood test would be
given to individuals testing positive for early-stage cognitive
impairment in primary care and referrals to specialty care would be
informed by the test results.
The model suggests that by 2033, people will wait an average of
nearly six years (70 months) to understand if they could be
eligible for new Alzheimer's treatments if their primary care
doctor only used brief cognitive assessments to make referrals. If
blood tests were used to rule out Alzheimer's, the average wait
times would be reduced to 13 months for Alzheimer's patients
because far fewer patients would need to see a specialist.
Researchers also determined that if blood tests and brief cognitive
assessments were used at the primary care level to rule in the
possibility of an Alzheimer's diagnosis, wait times to understand
eligibility for new treatments would fall to less than six months
on average because of reduced demand for Alzheimer's specialists
and the additional capacity now available for CSF or PET
testing.
"Our results suggest using blood tests to identify potential
candidates for treatments could make a significant difference in
treating people with early Alzheimer's," said Soeren Mattke, M.D., D.Sc., lead author of the
study and director of the Brain Health Observatory, at the
University of Southern California,
Los Angeles. "Currently, eligible
patients are falling outside of the treatment window because it
takes so long to receive a diagnosis. An easy-to-use blood test
could help address that problem."
About the Alzheimer's Association International
Conference® (AAIC®)
The Alzheimer's Association International Conference (AAIC) is
the world's largest gathering of researchers from around the world
focused on Alzheimer's and other dementias. As a part of the
Alzheimer's Association's research program, AAIC serves as a
catalyst for generating new knowledge about dementia and fostering
a vital, collegial research community.
AAIC 2024 home page: www.alz.org/aaic/
AAIC 2024 newsroom: www.alz.org/aaic/pressroom.asp
AAIC 2024 hashtag: #AAIC24
About the Alzheimer's Association®
The Alzheimer's Association is a worldwide voluntary health
organization dedicated to Alzheimer's care, support and research.
Our mission is to lead the way to end Alzheimer's and all other
dementia — by accelerating global research, driving risk reduction
and early detection, and maximizing quality care and support. Our
vision is a world without Alzheimer's and all other
dementia®. Visit alz.org or call 800.272.3900.
- Sebastian Palmqvist, M.D., Ph.D., et al. Evaluation of the
prospective use of blood biomarkers for Alzheimer's disease in
primary and secondary care. (Funders: Alzheimer's Association, the
National Institute of Aging)
- Gemma Salvadó, Ph.D., et al. Use of plasma p-tau217 as a
pre-screening method for detecting amyloid-PET positivity in
cognitively unimpaired participants: A multicenter study. (Funders:
Alzheimer's Association, European Union's Horizon 2020 Research and
Innovation Program under Marie
Sklodowska-Curie action, Alzheimerfonden, Strategic Research
Area MultiPark)
- Soeren Mattke, M.D., D.Sc., et
al. Impact of a High-Performing Blood Test on Wait Times for
Determination of Eligibility for a Disease-Modifying Alzheimer's
Treatment in the U.S. (Funder: C2N Diagnostics)
*** AAIC 2024 news releases may contain updated data that does
not match what is reported in the following abstracts.
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