New blood test shows great promise in the diagnosis of Alzheimer's disease
Lund
University – July 29, 2020 -- A new blood test demonstrated remarkable promise
in discriminating between persons with and without Alzheimer's disease. Persons at known genetic risk may be able to
detect the disease as early as 20 years before the onset of cognitive
impairment, according to a large international study. The results were published July 29 in
the Journal of the American Medical Association (JAMA) and
simultaneously presented at the Alzheimer's Association International
Conference.
For
many years, the diagnosis of Alzheimer's has been based on the characterization
of amyloid plaques and tau tangles in the brain, typically after a person dies.
An inexpensive and widely available blood test for the presence of plaques and
tangles would have a profound impact on Alzheimer's research and care.
According to the new study, measurements of phospho-tau217 (p-tau217), one of
the tau proteins found in tangles, could provide a relatively sensitive and
accurate indicator of both plaques and tangles -- corresponding to the
diagnosis of Alzheimer's -- in living people.
"The
p-tau217 blood test has great promise in the diagnosis, early detection, and
study of Alzheimer's," said Oskar Hansson, MD, PhD, Professor of Clinical
Memory Research at Lund University, Sweden, who leads the Swedish BioFINDER
Study and senior author on the study who spearheaded the international
collaborative effort. "While more work is needed to optimize the assay and
test it in other people before it becomes available in the clinic, the blood
test might become especially useful to improve the recognition, diagnosis, and
care of people in the primary care setting."
Researchers
evaluated a new p-tau217 blood test in 1,402 cognitively impaired and
unimpaired research participants from well-known studies in Arizona, Sweden,
and Colombia. The study, which was coordinated from Lund University in Sweden,
included 81 Arizona participants in Banner Sun Health Research Institute's
Brain Donation program who had clinical assessments and provided blood samples
in their last years of life and then had neuropathological assessments after
they died; 699 participants in the Swedish BioFINDER Study who had clinical,
brain imaging, cerebrospinal fluid (CSF), and blood-based biomarker
assessments; and 522 Colombian autosomal dominant Alzheimer's disease
(ADAD)-causing mutation carriers and non-carriers from the world's largest ADAD
cohort.
- In the Arizona
(Banner Sun Health Research Institute) Brain Donation Cohort, the plasma
p-tau217 assay discriminated between Arizona Brain donors with and without
the subsequent neuropathological diagnosis of "intermediate or high
likelihood Alzheimer's" (i.e., characterized by plaques, as well as
tangles that have at least spread to temporal lobe memory areas or beyond)
with 89% accuracy; it distinguished between those with and without a
diagnosis of "high likelihood Alzheimer's" with 98% accuracy;
and higher ptau217 measurements were correlated with higher brain tangle
counts only in those persons who also had amyloid plaques.
- In the
Swedish BioFINDER Study, the assay discriminated between persons with the
clinical diagnoses of Alzheimer's and other neurodegenerative diseases
with 96% accuracy, similar to tau PET scans and CSF biomarkers and better
than several other blood tests and MRI measurements; and it distinguished
between those with and without an abnormal tau PET scan with 93% accuracy.
- In the
Colombia Cohort, the assay began to distinguish between mutation carriers
and non-carriers 20 years before their estimated age at the onset of mild
cognitive impairment.
In
each of these analyses, p-tau217 (a major component of Alzheimer's
disease-related tau tangles) performed better than p-tau181 (another component
of tau tangles and a blood test recently found to have promise in the diagnosis
of Alzheimer's) and several other studied blood tests.
Other
study leaders include Jeffrey Dage, PhD, from Eli Lilly and Company, who
developed the p-tau217 assay, co-first authors Sebastian Palmqvist, MD, PhD,
and Shorena Janelidz, PhD, from Lund University, and Eric Reiman, MD, Banner
Alzheimer's Institute, who organized the analysis of Arizona and Colombian
cohort data.
In
the last two years, researchers have made great progress in the development of
amyloid blood tests, providing valuable information about one of the two
cardinal features of Alzheimer's. While more work is needed before the test is
ready for use in the clinic, a p-tau217 blood test has the potential to provide
information about both plaques and tangles, corresponding to the diagnosis of
Alzheimer's. It has the potential to advance the disease's research and care in
other important ways.
"Blood
tests like p-tau217 have the potential to revolutionize Alzheimer's research,
treatment and prevention trials, and clinical care," said Eric Reiman, MD,
Executive Director of Banner Alzheimer's Institute in Phoenix and a senior
author on the study.
"While
there's more work to do, I anticipate that their impact in both the research
and clinical setting will become readily apparent within the next two
years."
Alzheimer's
is a debilitating and incurable disease that affects an estimated 5.8 million
Americans age 65 and older. Without the discovery of successful prevention
therapies, the number of U.S. cases is projected to reach nearly 14 million by
2050.
https://www.sciencedaily.com/releases/2020/07/200729114404.htm
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