PR84922

CHICAGO, July 29, 2020 /PRNewswire=KYODO JBN/ --

A simple blood test for Alzheimer's would be a great advance for individuals

with -- and at risk for -- the disease, families, doctors and researchers.

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At the Alzheimer's Association International Conference(R)  (

https://c212.net/c/link/?t=0&l=en&o=2868176-1&h=4051985089&u=https%3A%2F%2Fwww.alz.org%2Faaic&a=Alzheimer%27s+Association+International+Conference

  )(AAIC(R)) 2020, scientists reported results of multiple studies on advances

in blood "tests" for abnormal versions of the tau protein, one of which may be

able to detect changes in the brain 20 years before dementia symptoms occur. In

particular, the reports focus on a specific form of tau known as p-tau217,

which seems to be the most specific to Alzheimer's and the earliest to show

measurable changes.

Changes in brain proteins amyloid and tau, and their formation into clumps

known as plaques and tangles, respectively, are defining physical features of

Alzheimer's disease in the brain. Buildup of tau tangles is thought to

correlate closely with cognitive decline. In these newly reported results,

blood/plasma levels of p-tau 217, one of the forms of tau found in tangles,

also seem to correlate closely with buildup of amyloid.

Currently, the brain changes that occur before Alzheimer's dementia symptoms

appear can only be reliably assessed by positron-emission tomography (PET)

scans, and from measuring amyloid and tau proteins in spinal fluid (CSF). These

methods are expensive and invasive. And, too often, they are unavailable

because they are not covered by insurance or difficult to access, or both.

"There is an urgent need for simple, inexpensive, non-invasive and easily

available diagnostic tools for Alzheimer's. New testing technologies could also

support drug development in many ways. For example, by helping identify the

right people for clinical trials, and by tracking the impact of therapies being

tested," said Maria C. Carrillo, Ph.D., Alzheimer's Association chief science

officer. "The possibility of early detection and being able to intervene with a

treatment before significant damage to the brain from Alzheimer's disease would

be game changing for individuals, families and our healthcare system."  

A blood test, for example, will enable interpretation and understanding of

Alzheimer's progression in much larger, more diverse and more robust

populations.

"While these new reports are encouraging, these are early results, and we do

not yet know how long it will be until these tests are available for clinical

use. They need to be tested in long-term, large-scale studies, such as

Alzheimer's clinical trials," Carrillo added. "In addition, we need to continue

research to refine and verify the tests that are the current state-of-the-art

-- including cerebrospinal fluid and PET imaging biomarkers."

Blood P-tau217 Detects Alzheimer's Disease (i.e., Both Plaques and Tangles)

with High Accuracy

As reported at AAIC 2020, an international team of researchers have identified

a highly accurate, blood-based biomarker for the detection of Alzheimer's

disease by measuring levels of p-tau217 in blood, and validated the finding in

multiple, diverse populations. The scientists found that, "the diagnostic

precision of blood p-tau217 was as high as established diagnostic methods,

including positron emission tomography (PET) imaging and cerebrospinal fluid

biomarkers, which are invasive, costly and less available."

The research team was led by Oskar Hansson, M.D., Ph.D., from Lund University,

Sweden in coordination with Sebastian Palmqvist, M.D., Ph.D., and Shorena

Janelidze, Ph.D. from Lund, Eric Reiman, M.D., from Banner Alzheimer's

Institute, USA, Jeffrey Dage, Ph.D., from Eli Lilly, USA, and other research

colleagues. The Lund University researchers presented the results at AAIC, and

they were also published online.

They studied three different cohorts comprising more than 1,400 cases,

including a large clinic-based study from Sweden (the BioFINDER-2 study), a

cohort with neuropathological confirmation of Alzheimer's (the Arizona Study of

Aging and Neurodegenerative Disorders), and a large kindred with

genetically-caused Alzheimer's (Colombian autosomal-dominant Alzheimer's

registry).They analyzed other current experimental biomarkers (p-tau217,

p-tau181, AB42/40 and neurofilament light chain) in both blood and

cerebrospinal fluid, as well as performed PET imaging for tau and amyloid

pathology.

The main finding of the study was that blood p-tau217 could distinguish

Alzheimer's from other neurodegenerative disorders with diagnostic accuracy

between 89 and 98 percent. In this study, the p-tau271 assessment was more

accurate for Alzheimer's than blood-based tests for p-tau181, neurofilament

light or amyloid beta 42/40 ratio, as well as magnetic re

sonance imaging (MRI). In fact, according to the researchers, performance was

similar to significantly more costly methods, such as PET imaging and

cerebrospinal fluid biomarkers.

The researchers also found that p-tau217 analyzed in blood collected during

life could detect tau brain changes measured in brain tissue analyzed after

death. These tau brain changes are thought to be related to amyloid plaque

accumulation. P-tau217 distinguished persons who had plaques and tangles from

those without Alzheimer's pathology with 89% accuracy, those with plaques and

more extensive tangles with 98% accuracy, and the outcome of tau PET imaging

with 93% accuracy.

The p-tau217 levels were increased about seven-fold in Alzheimer's, and, in

individuals with a gene causing Alzheimer's, the levels started to increase

already 20 years before onset of cognitive impairment. "This test, once

verified and confirmed, opens the possibility of early diagnosis of Alzheimer's

before the dementia stage, which is very important for clinical trials

evaluating novel therapies that might stop or slow down the disease process,"

Hansson said.

Blood Amyloid and P-tau are Precise Markers of Brain Amyloidosis, Tauopathy

To advance research on a blood test for Alzheimer's disease, Suzanne Schindler,

M.D., Ph.D., of Washington University School of Medicine in St. Louis and

colleagues evaluated the performance of a variety of amyloid and tau measures

in blood.

Using mass spectrometry, the scientists mapped the blood plasma tau protein and

compared the results to CSF and PET imaging measures. Compared to the

better-known tau form p-tau181, they found that p-tau217 was more closely

linked to build up of amyloid plaques in the brain as measured by a PET scan.

Additionally, their findings suggest that measuring levels of several different

forms of p-tau in blood over time may enable clinicians and researchers to

track the stages of Alzheimer's progression in people living with the disease.

According to the researchers, a blood test for Alzheimer's disease that

incorporates both amyloid and tau measures may allow earlier and more accurate

dementia diagnoses not only in research participants but also in clinic

patients.

The scientists launched the Study to Evaluate Amyloid in Blood and Imaging

Related to Dementia (SEABIRD) to develop and validate Alzheimer's blood

biomarkers in a cohort that is more diverse and representative of the greater

St. Louis region. SEABIRD will enroll more than 1,100 individuals including

diversity in race, socioeconomic status, medical history and cognitive status.

Plasma P-tau217 is Comparable to P-tau181 for Distinguishing Between

Alzheimer's and Frontotemporal Lobar Degeneration

Recent studies have shown that p-tau181 is more than three times as high in

people with Alzheimer's compared to healthy elderly people or people with a

neurodegenerative disease known as frontotemporal lobar degeneration (FTLD).  

At AAIC 2020, Elisabeth Thijssen, M.Sc., and Adam L. Boxer, M.D., Ph.D., of the

UCSF Memory and Aging Center and colleagues reported a comparison of p-tau181

to a related form of tau called p-tau217 to determine which form can best

identify people with Alzheimer's.

The retrospective study included 617 participants: 119 healthy controls, 74

Alzheimer's cases (biomarker-confirmed) and 294 FTLD. In this study group,

plasma p-tau181 was increased three-fold in people with Alzheimer's compared to

controls and FTLD. Increase in plasma p-tau217 was even higher; five-fold in

Alzheimer's compared to healthy controls and four-fold relative to FTLD. The

plasma comparison results mirrored the findings of tau PET imaging in the

brain. P-tau181 had a 91% accuracy and p-tau217 had 96% accuracy in predicting

whether a person had a tau positive brain scan.

According to the researchers, the study shows that both p-tau217 and p-tau181

measured in blood are elevated in Alzheimer's, and that measurements closely

correspond to "gold standard" PET scan results. These blood tests are likely to

be useful for diagnosing Alzheimer's and as monitoring tools in clinical trials

to measure treatment effects of new Alzheimer's therapies.

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 2020 home page: www.alz.org/aaic

    -- AAIC 2020 newsroom: www.alz.org/aaic/pressroom.asp  

    -- AAIC 2020 hashtag: #AAIC20

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. Visit https://www.alz.org/ or call 800.272.3900.

    -- Oskar Hansson, PhD, et al. Phospho-tau217 and phospho-tau181 in plasma

       and CSF as biomarkers for Alzheimer's disease. (Funder(s): Swedish

       Research Council, the Knut and Alice Wallenberg Foundation, and the

       Swedish Alzheimer Foundation)

    -- Shorena Janelidze, PhD, et al. Plasma phospho-tau217 is a potential

       early diagnostic and prognostic biomarker of Alzheimer's disease.

        (Funder(s): Swedish Research Council, the Knut and Alice Wallenberg

       Foundation, and the Swedish Alzheimer Foundation)

    -- Suzanne Schindler, MD, PhD, et al. Mass spectrometry measures of

       plasma Aâ, tau and p-tau isoforms relationship to amyloid PET, tau

       PET, and clinical stage of Alzheimer's disease. (Funder(s): U.S.

       National Institute on Aging)

    -- Elisabeth Thijssen, MSc, et al. Comparative diagnostic performance of

       plasma P-tau217 and P-tau181 in Alzheimer's Disease and Frontotemporal

       Lobar Degeneration and correlations with [18F]Flortaucipir-PET uptake.

        (Funder(s): U.S. National Institute on Aging, National Center for

       Advancing Translational Sciences, Tau Research Consortium)

SOURCE  Alzheimer's Association

CONTACT: Alzheimer's Association Media Line, +1.312.335.4078, media@alz.org, or

AAIC 2020 Press Office, aaicmedia@alz.org