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Blood Test for Alzheimer’s

Blood Test for Alzheimer’s up to 94% When all of these factors were
Accurate accounted for in the analysis, the
accuracy of the blood test raised to
New tests can detect dementia years before 94%, with age and genetic status
any outward signs appear. accounting for all of the
Early brain changes due to Alzheimer’s improvement.
disease may soon be detected with a simple “Sex did affect the amyloid beta
blood draw in your doctor’s office, according ratio, but not enough to change
to researchers. Doctors have been hoping for whether people were classified as
such a test for years — one that providers can amyloid positive or amyloid
administer in the office at a reasonable cost. negative, so including it didn’t
They have been searching for an alternative improve the accuracy of the analysis,”
to the $4,000 PET brain scan currently in use. says first author Suzanne Schindler,
“We need something quicker and dirtier. It an assistant professor of neurology.
doesn’t have to be perfect” to be useful for Another factor in the improved
screening, said Maria Carrillo, the percentage was that scientists had
Alzheimer’s Association’s chief science initially labeled some blood results
officer. as false positives when the PET scan
Dr. Richard Hodes, director of the National didn’t detect any disease. However,
Institute on Aging, said that currently the some of these people tested positive
best use for the tests was in research because on subsequent scans taken an average
analysts can select and monitor people in of four years later. Far from being
much larger numbers than was possible wrong, the blood test had been able
previously for federally funded studies. to identify those with Alzheimer’s
“In the past year, we’ve seen a dramatic that the esteemed brain scan had
acceleration in progress” on these tests, he missed.
said. “This has happened at a pace that is far Clumps of damaging amyloid beta
faster than any of us would have expected.” protein begin to form in the brain up
Alzheimer’s Prevalence to two decades before outward signs
Alzheimer’s is the most common form of of the disease appear. Scientists can
dementia, which about 50 million people detect the level of the protein in
have worldwide. There is no cure, despite a blood and use that information to
massive effort to find one from dozens of predict if it is accumulating in the
research groups. One hypothesis is that too brain.
much brain damage had already occurred in A handful of research groups
past test subjects, and it was too late for them around the globe have recently
to get better. Another problem has been that reported similar success. Though the
people were enrolled in research groups who techniques vary slightly, all of the
had issues other than Alzheimer’s, because groups are reporting high accuracy
the disease has been difficult to diagnose. and earlier diagnosis.
Research Specifics “Everyone’s finding the same thing
The latest research, published … the results are remarkably similar
in Neurology, uses mass spectrometry to across countries, across techniques,”
measure two forms of amyloid protein in the said Dr. Randall Bateman of
blood: amyloid beta 42 and amyloid beta 40. Washington University School of
All but 10 of the 158 study participants were Medicine in St. Louis, whose work is
cognitively normal, and each provided a PET supported by the U.S. government
brain scan used to detect Alzheimer’s. and the Alzheimer’s Association. He
Scientists designated the blood sample and guesses a screening test could be
PET scan amyloid positive or negative, and ready as soon as three years from
the scan and bloodwork agreed 88% of the now.
time. That was very good, but not accurate What good is a blood test if there’s
enough for clinical diagnosis. no cure for the disease, you may ask.
Researchers decided to incorporate several Plenty, according to researchers.
known risk factors for Alzheimer’s. The risk “What people want most of all is a
of developing the disease doubles every five diagnosis” if they’re having
years after age 65, making age the biggest symptoms, said Jonathan Schott of
factor. Some people carry a genetic variant University College London. “What
dubbed APOE4, raising their risk three- to we don’t like is not knowing what’s
fivefold. And sex is a factor, since two out of going on.”
three patients are women.

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