Another Blood Test for Alzheimer's Shows
WEDNESDAY, Aug. 3 (HealthDay News) -- A blood test that screens
for certain markers in the blood called "autoantibodies" is showing
promise in diagnosing Alzheimer's disease, researchers report.
The blood test correctly detected Alzheimer's disease in people
already diagnosed with the devastating brain disorder with 96
percent accuracy, according to the researchers. The test could also
distinguish who didn't have the disease from a control group of
non-affected adults with 92.5 percent accuracy.
Though outside experts said the findings may be another step
toward a quicker, easier way to diagnose Alzheimer's, they
cautioned that there's still a long way to go.
The researchers who developed the test have not yet determined
how early in the course of the disease the test works, such as
whether the test would be able to detect people with the earliest
signs of the disease or even before symptoms appeared, said Dr.
Aron Buchman, a neurologist in the Rush Alzheimer's Disease Center
at Rush University Medical Center in Chicago who was not involved
with the research. He pointed out that the patients tested had
already been diagnosed with Alzheimer's.
"This is important work that is at the edge of the envelope where the field is moving," said Buchman. "But Alzheimer's disease is a progressive disorder that takes many years to develop, with the end stage being dementia. This study didn't look at any people with mild cognitive impairment [mild memory loss that may progress to dementia] or who had Alzheimer's pathology in the brain but were not yet having clinical symptoms."
The study is published in the Aug. 3 online edition of
In the study, researchers at the University of Medicine and
Dentistry of New Jersey-School of Osteopathic Medicine put a drop
of blood taken from 50 people with Alzheimer's disease and 40
people without dementia onto slides called "human protein
microarrays." The slides contained more than 9,400 human protein
antigens, about one-third of all proteins made by humans.
Antigens stimulate the production of antibodies, and the
researchers found that the blood reacted with some 1,000
autoantibodies present in the microarrays.
While regular antibodies are produced by the immune system in
response to viruses and other pathogens, autoantibodies are
produced by the immune system in response to the body's own
proteins, said senior study author Robert Nagele, founder of Durin
Technologies, Inc., which is designed to commercialize diagnostic
tools for neurodegenerative diseases such as Alzheimer's. He is
also a professor of medicine at the University of Medicine and
Dentistry of New Jersey.
But no one is sure what exactly autoantibodies do. One theory is
that they are involved with clearing debris, Nagele said.
Researchers used a sophisticated computer analysis to further
narrow the test to 10 autoantibodies that, when present, could
predict which patients had Alzheimer's and which didn't. They also
found that the test predicted who had Alzheimer's and who had
Parkinson's -- another neurodegenerative disease -- with 86 percent
"We know we can detect Alzheimer's disease in people who have been diagnosed, but the real exciting question is if it's possible for this test [to] detect people when they are pre-symptomatic," Nagele said.
The problem is that even if someone is diagnosed with the brain
disease before symptoms appear, there is no cure or treatment to
stop its relentless progression. Nagele acknowledged this reality,
but has said that scientists are working "feverishly" to develop
"Although there are no treatments now, we are always hopeful one will come soon. If and when such a treatment becomes available, we know early treatment is always better than later," Nagele said. "It's hard to correct damage that already exists. So it would be wonderful to detect people several years before they have symptoms so we can slow down or halt the progression of the disease."
Currently, Alzheimer's is diagnosed after people start having
memory problems or other unusual changes in behavior. They undergo
a detailed medical interview, a memory assessment test and
sometimes an MRI to look for brain shrinkage, Nagele said.
Nagele is seeking a commercial partner and will seek U.S. Food
and Drug Administration approval to market the test for use in
diagnosing Alzheimer's in the upcoming months, he said.
The study was funded by an investment in Durin Technologies by
the Foundation Venture Capital Group LLC, a New Jersey Health
Foundation affiliate that invests in start-up companies founded by
researchers at UMDNJ. Co-author Eric Nagele is also a paid
consultant to Durin and co-author Benjamin Belinka is Durin's
Discussing the Alzheimer's test, Buchman noted the research was
far from definitive. He pointed out that the average age of the
Alzheimer's patients was nearly 80, while the age of the controls
was 40. That means researchers did not prove that the
autoantibodies were necessarily related to Alzheimer's, but instead
could be a product of something else, such as aging.
Thomas Kodadek, a professor of chemistry and cancer biology at
The Scripps Research Institute in Jupiter, Fla., raised another
criticism. Although researchers found a statistical association
between the presence of the autoantibodies and Alzheimer's, he
said, the lack of understanding about the purpose of autoantibodies
or what they have to do with dementia may make acceptance of such a
test by physicians more difficult.
"What a physician would like to know is, here is a marker that is somehow associated with the disease in a way a physician can understand, such as cholesterol and heart disease," he said. "It's not really known what autoantibodies do or why they are there. Most of the proteins that bind these antibodies, they have no known function, and there is no clear mechanistic connection to Alzheimer's."
Kodadek is also working on developing an Alzheimer's blood test
that screens for antibodies and is running into similar issues, he
"At the end of the day, is it crucial to know what the function of these autoantibodies are? No," Kodadek said. "Even if you don't understand what it does, it could still be an important biomarker. But these things are not black and white markers that are completely unique to Alzheimer's patients, which is ideally what you would like to have."
The U.S. National Institute on Aging has more on
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