Brain Scan Technique Spots Alzheimer’s
Brain Imaging Model Distinguishes Alzheimer’s Disease From Other Types of Dementia
March 26, 2008 -- A computer-assisted imaging technique that measures sugar
metabolism within a critical area of the brain could
hold the key to the early diagnosis of Alzheimer's disease and other dementias.
Researchers say that the technique was accurate 94% of the time in
distinguishing Alzheimer's disease from other dementias in a newly reported
study published in the March issue of the Journal of Nuclear
It was also able to identify brain patterns associated with very early
cognitive decline, raising hopes that the imaging model might lead to earlier
diagnosis and better outcomes among patients with Alzheimer's and other
dementias, says study researcher Lisa Mosconi, PhD.
"Because the incidence of (Alzheimer's and related disorders) is
expected to increase dramatically as the baby boomer generation ages, accurate
diagnosis is extremely important -- particularly at the early and mild stages
of dementia when lifestyle changes and therapeutic
interventions would be most effective," Mosconi says.
Diagnosing Alzheimer's Disease
Mosconi and colleague Mony de Leon, EdD, both of New York University's
Center for Brain Health, developed the brain scan-based computer program after
identifying key changes in the part of the brain known as the hippocampus early
in the course of Alzheimer's disease.
Specifically, they found that the hippocampus, which is associated with
learning and memory, metabolizes glucose less efficiently as dementia
progresses. Glucose is the fuel that allows the brain to function properly.
Using positron emission tomography (PET), the researchers were able to
highlight glucose consumption patterns within the hippocampus and identify
specific images associated with normal brain function, mild cognitive
impairment, and different types of dementia, including Alzheimer's.
Their latest study included 548 people examined at seven separate centers
who were mostly in their 60s and 70s. The participants had either no evidence
of cognitive decline, mild cognitive impairment, Alzheimer's disease, or
dementia due to other causes, confirmed through a battery of neurological and
Each patient was injected with the radioactive isotope FDG, which mimicked
glucose once it entered the body. After about 30 minutes researchers began
taking pictures of the brain using PET imaging, and the images were later
analyzed using the computer program developed at NYU.
By comparing images of the cerebral cortex at the brain's surface to those
of the hippocampus deep within the brain, the researchers could accurately
distinguish between patients with normal brain function and specific dementias,
"We were even able to identify people with mild cognitive impairment
that did not meet the criteria for dementia," Mosconi tells WebMD.
The computer-assessed imaging model also appeared to predict which type of
dementia someone with mild cognitive impairment would eventually have.
'Missing Piece of the Puzzle'
Mosconi and colleagues are now evaluating follow-up data on the patients in
the study to determine how accurate the imaging was at predicting their
clinical course. The next step after this is to examine the imaging technique
outside the clinical trials setting.
"Right now we can't say if the results will apply to the normal
population, where confounding medical conditions are common," she says.
"But that is certainly the hope."
Society for Nuclear Medicine President Sandy McEwan, MD, tells WebMD that
the NYU research represents a potentially seminal advance in the use of imaging
for the early diagnosis of Alzheimer's and other dementias.
He says the fact that the imaging was conducted at different centers within
the United States and Europe shows that the technique is reproducible in the
"This may be the piece of the puzzle that we have been missing," he