Dramatic new scans show brain cells quickly and steadily disappearing
in patients with Alzheimer's disease, reported an international team of researchers.
They used magnetic resonance imaging, also known as MRI, to chart a
five percent annual loss of brain cells in Alzheimer's patients -- up to
ten percent in key memory areas. In contrast, healthy volunteers monitored
in the study lost less than one percent of their brain cells a year.
"For the first time, you can see Alzheimer's disease progressing in
living patients," said Paul Thompson, an assistant professor of neurology
at the University of California Los Angeles School of medicine, who led the
study.
"We were stunned to see a spreading wave of tissue loss. Initially confined
to memory areas, this loss moved across the brain like a lava flow, destroying
more and more tissue as the disease progressed."
Writing in the Journal of Neuroscience, the researchers said
their findings would help doctors check to see if treatments are helping,
and perhaps help chart the course of the disease.
Alzheimer's is assessed using standard tests of a patient’s behavior
and performance, rather than any physical evidence. This will probably continue
to be the case, said Dr. Sid Gilman, director of the Alzheimer's center at
the University of Michigan.
"The diagnosis of Alzheimer's disease really depends upon demonstration
of cognitive dysfunction," Gilman said in a telephone interview.
"No amount of PET scanning or MRI scanning will make the diagnosis.
There are anecdotal stories of people dying who had scored normal on tests
of cognitive function a few weeks before and upon death the brain can show
definitive signs of Alzheimer’s."
Charting future treatment However, such a test would be extremely
useful in charting future treatments, Gilman said. "Currently all we have
is symptomatic treatment," he said. “We have no treatment that stops the
progression." But, he added, researchers are working on ways to stop the
now-incurable disease, such as vaccinations that might stop the buildup of
toxic proteins in the brain.
"We are on the verge of some very exciting discoveries in Alzheimer’s
disease, so that a biomarker that told us the disease itself was not progressing
would be extremely important," Gilman said.
For their study, Thompson and colleagues at UCLA, in Britain and in
Australia scanned the brains of 12 Alzheimer’s patients and 14 healthy volunteers.
MRI gives a finer image of bodily structures than x-rays. "They got a scan
every three months," Thompson said in a telephone interview.
On average, the Alzheimer's patients lost 5,3 percent of their brain
cells each year. In memory regions they lost up to ten percent. "Memory systems
go first and then the frontal areas involved in inhibition and self-control
and later areas involved in emotion," Thompson said. "Another feature is
that some parts of the brain are completely spared. One example is the visual
area. Why it is, is a mystery."
Thompson hopes the method could not only be used to compare treatments
for Alzheimer's, but perhaps to see if exercise and mental exercise could
prevent or delay Alzheimer's in people at a high risk of the disease.
