Mapping Alzheimer's
progress Barbara
Gengler MAY 06, 2003
RESEARCHERS at the
University of California, Los Angeles and Australia's
University of Queensland have created 3D video maps showing
the progression of Alzheimer's disease.
To track the
death of brain cells, the research team scanned 12 Alzheimer's
patients and 14 healthy elderly volunteers with MRI brain
scans every three months for two years.
Computational techniques used imaging data from 60,000
scanned points to compare the affected brains with healthy
brains.
Alzheimer's disease is a progressive, neuro-degenerative
brain disease characterised by memory loss, language
deterioration, poor judgment and indifferent attitude. There
is no cure for Alzheimer's, which affects at least 20 million
people worldwide.
The process began with raw data acquired on a Bruker AVANCE
Electronics Medspec S200 MRI (magnetic resonance imaging)
scanner interfaced to a SGI O2 system and preprocessed on a
SGI Octane system at the University of Queensland's Centre for
Magnetic Resonance.
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The videos were built on an SGI Onyx visualisation system
that started with data sets assembled on a 64-processor SGI
Origin 3000 server at UCLA.
By using the new image analysis technique, the researchers
found Alzheimer's patients lost an average of 5.3 per cent of
their grey matter a year.
Brain cells were purged even faster in some brain regions,
with patients losing up to 10 per cent in memory regions each
year. In contrast, healthy elderly volunteers lost only 0.9
per cent of their brain tissue annually.
A leading researcher for the project, Paul Thompson, an
assistant professor of neurology at the David Geffen School of
Medicine at UCLA, says for the first time Alzheimer's disease
progressing in living patients can be seen.
"Basically we take a sequence of MRI scans and a powerful
computer lines them up and compares how much tissue is being
lost in different parts of the brain," he says. "Then a colour
coded picture is created, telling you how fast each brain
region is losing tissue."
He says combining these maps from many people gives the
first dynamic picture of how Alzheimer's spreads in the brain.
"You see memory areas are affected first, then areas
involved in emotion. Some areas, like sensation and vision,
stay intact for many years," Thompson says.
"Essentially you catch Alzheimer's 'red handed'. For the
first time you can see the disease moving in the brain, like a
robber caught in the headlights."
He maintains that with these video maps of the brain, the
imaging would allow doctors and researchers to pinpoint if
medications are effective in combating the disease or slowing
its progression.
"We were stunned to see a spreading wave of tissue loss,"
Thompson says. "Initially confined to memory areas, this loss
moved across the brain like a wildfire, destroying more and
more tissue as the disease progressed."
He says the researchers will urgently apply this method to
reveal how drugs and vaccines combat the wave of brain damage
caused by Alzheimer's disease.
Thompson says he met the University of Queensland's
researchers, Greig de Zubicaray and Andrew Janke, at a brain
imaging conference in Montreal three years ago.
"I was doing a talk on how you can make 'time-lapse movies'
to show how the brain develops in childhood," he said, adding
that work was based on MRIs of kids collected over a period of
several years.
Greig mentioned that this same technique might help detect
brain changes in Alzheimer's disease as well, according to
Thompson, and they were working intensively in that area.
"He was absolutely right," Thompson says. "Actually I also
knew their work very well before meeting them. This is because
the Queensland Center for Magnetic Resonance (in Brisbane) is
famous for collecting superb quality MRI scans of the brain.
They are extremely well respected worldwide for this."
Thompson says there are two immediate uses. The first is to
apply the technique to more people, to begin to see how early
Alzheimer's can be detected.
The second practical goal is to see if drugs are effective
in slowing Alzheimer's, and which drugs are best in opposing
the physical spread of the disease (which hasn't been visible
until now), according to Thompson.
He noted the most powerful way to do that is first to build
up a detailed database on how Alzheimer's normally progresses
over time, storing information on which parts of the brain
change most, and how fast.
"The Queensland group is absolutely unique in that respect,
as their MRI scans show the greatest promise in defining how
Alzheimer's progresses and for detecting it early," Thompson
says. "I can say that with confidence as we have over 50
collaborations with imaging centres around the world, many of
them focusing on dementia research."
Findings of the researchers work appeared in the Journal of
Neuroscience.
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