Early Alzheimer’s Tests Show Promise
Tests Could Allow Detection, Treatment Before Symptoms Arise
June 12, 2007 -- Research appears to be moving closer to developing early
tests for Alzheimer’s disease, a milestone that could allow treatment for the
degenerative disease to begin at a much earlier stage than it does today.
Most patients today do not begin treatment until after significant deficits
show up, making the prospect of early predictive tests highly attractive. If
perfected, the tests could allow physicians to be on close watch for memory
loss and other early signs of memory loss that presage the onset of
Drugs currently approved for treating Alzheimer’s are limited to addressing
its symptoms. The tests could also become more valuable if drugs treating the
underlying biological mechanisms of the disease become available. In that case,
prevention may become possible.
At the 2007 Alzheimer’s Association International Conference on Prevention
of Dementia in Washington, a team of Norwegian researchers announced they
had isolated some 1,200 genes that, taken together, can closely predict
When researchers combined the genes and tested the blood of known
Alzheimer’s patients, they found the genes could predict onset of the disease
with 85% accuracy.
A second test containing just 96 genes predicted the disease with 80%
accuracy, though presumably at a potentially lower cost than the more complex
The tests are currently in large-scale trials with results expected next
year, Anders Lönneborg, PhD, research director at DiaGenic ASA, the company
pursuing the test, said at the International Conference on the Prevention of
Testing for Proteins
Early detection could also get a boost from another blood test under
investigation at a Belgian company. Researchers say they can use existing lab
tests to predict which patients are at risk for developing dementia later.
Scientists identified two forms of amyloid protein circulating in the blood.
Since the protein is known to be a marker for Alzheimer’s disease in the brain,
finding abnormalities in blood levels could also wind up being a reliable early
predictor of disease.
Early tests show that a blood test comparing the two amyloid proteins
identifies most patients at risk for Alzheimer’s, said Geert DeMeyer, PhD, a
biostatistician with Innogenetics, the firm hoping to market the test.
The test does not definitively tell who will develop the disease. “This is
not a diagnostic test," DeMeyer said. "What it can do is predict what
could happen to people down the road."
Another research team says they can use a combination of magnetic resonance
imaging (MRI) scans and positron emission tomography (PET imaging) to identify
the earliest changes of the brain that are characteristic of mild cognitive
impairment (MCI). MCI is marked by memory problems that aren't severe enough
for dementia diagnosis.
MRIs, which provide detailed brain images, can already be used to help
identify physical signs of cognitive impairment in the brain. Still, the
accuracy is limited.
Researchers combined the MRI scans with PET imaging of blood flow in the
brain in a small study of 30 people (half with MCI and half who without
cognitive problems), to pinpoint patterns of changes in the brain researchers
say provided diagnosis of mild cognitive impairment 100% of the time.
“In many individuals, they can be identified and measured even before the
patient’s mental processes deteriorate to the point of clinical symptoms,” said
Christos Davatzikos, PhD, a researcher at University of Pennsylvania in
Alzheimer's can be elusive to spot in a loved one, especially
in the early stages. How did you and your loved one's medical team determine it was
Alzheimer's? What us your diagnostic journey? Tell us in WebMD's
Alzheimer's Disease: Support Group message board.