Psychiatric News August 5, 2005
Volume 40 Number 15
© 2005 American Psychiatric Association
p. 33
Research Findings Lead to Test To Detect Early Alzheimer's
Joan Arehart-Treichel
A new method for measuring hippocampal glucose metabolism might
correctly predict, in as many as 85 out of 100 cases, who is going to develop
Alzheimer's within nine years.
Five years ago Mony de Leon, Ed.D., a professor of psychiatry at New York
University, and colleagues reported that one of the first signs that a brain
is succumbing to Alzheimer's is that the hippocampus metabolizes glucose less
efficiently than before (Psychiatric News, September 1, 2000).
Lisa Mosconi, Ph.D., one of the research scientists working with de Leon,
has now designed a test to detect early Alzheimer's that is based on that
discovery. The test is called HipMask. Preliminary results suggest that the
test is fairly accurate.
Traditionally, there have been two ways to analyze hippocampal glucose
metabolism, Mosconi explained to Psychiatric News. One is called the
regions of interest (ROI) procedure, which involves taking an MRI scan as well
as a PET scan of a subject's brain and using both to extract the desired data.
This process takes about four to five days per subject.
The other procedure is called voxel-based analysis and uses only a PET scan
of a subject. It is quick and works well for measuring glucose metabolism in
large regions of the brain, but not so well in small brain structures such as
the hippocampus.
Moreover, when Mosconi and her colleagues compared the two methods in the
same subjects, they sometimes found a reduction in hippocampal metabolism with
the ROI procedure, but not with the voxel-based one.
They also learned that some other scientific groups had similar
difficulties. So they decided that a new method for interpreting PET scan
results of hippocampal glucose metabolism was needed that combines the
accuracy of the ROI procedure with the speed of voxel-based analysis.
Mosconi now appears to have designed such a method—the HipMask. It
takes only five minutes to extract and analyze the desired data from an
already performed PET scan.
Specifically, Mosconi and her colleagues tested the HipMask on PET scans of
brains of 53 older subjects whom they had already followed for 10 to 24 years
and for whom they knew the outcome as far as Alzheimer's was concerned. They
found that the HipMask correctly predicted a decline from normal aging to
Alzheimer's with 85 percent accuracy.
"In other words, if we had 100 subjects now," Mosconi told
Psychiatric News, "we might be able to correctly predict who is
going to get Alzheimer's and who is going to remain normal nine years later in
85 out of 100 cases."
Of course, these findings need to be replicated, de Leon stressed in an
interview. But "for research purposes the HipMask is ready, and we are
starting a number of collaborations with groups from around the world,"
he said.
Whether the HipMask procedure might also be used to diagnose Alzheimer's in
its very early stages remains to be seen, he added. However, he sees it as a
distinct possibility. "It could be used by any nuclear medicine
specialist, neurologist, or radiologist, as the protocol is easy to use, and
it would not take long to establish reference norms for a particular
machine," he said.
Mosconi presented results documenting HipMask's accuracy at the Alzheimer's
Association International Conference on Prevention, held in Washington, D.C.,
in June. A description of the technique appeared in the June 14
Neurology.
The research was funded by the National Institutes of Health.
An abstract of "Reduced Hippocampal Metabolism in MCI and
AD" is posted at
<www.neurology.org/cgi/content/abstract/64/11/1860>.
Neurology 2005 641860[Abstract/Free Full Text]
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