Computer program uses brain
scans
to assess risk of Alzheimer’s
Newswise — New York University
School of Medicine researchers have developed a brain scan-based
computer program that quickly and accurately measures metabolic
activity in a key region of the brain affected in the early stages
of Alzheimer’s disease. Applying the program, they demonstrated that
reductions in brain metabolism in healthy individuals were
associated with the later development of the memory robbing disease,
according to a new study.
“This is the first demonstration that reduced metabolic activity in
the hippocampus may be used to help predict future Alzheimer’s
disease,” says Lisa Mosconi, Ph.D., a research scientist in the
Department of Psychiatry, who developed the computer program and led
the new study. “Although our findings need to be replicated in other
studies,” she says, “our technique offers the possibility that we
will be able to screen for Alzheimer’s in individuals who aren’t
cognitively impaired.”
Dr. Mosconi and colleagues have
recently published the technical details of the program, called “HipMask,”
in the June 2005 issue of the journal Neurology. She will present
the new findings on June 20 at the Alzheimer’s Association
International Conference on Prevention of Dementia held in
Washington.
The computer program is an image
analysis technique that allows researchers to standardize and
computer automate the sampling of PET brain scans. The NYU
researchers hope the technique will enable doctors to measure the
metabolic rate of the hippocampus and detect below-normal metabolic
activity.
The technique grew out of years of
research by Mony de Leon, Ed.D., Professor of Psychiatry and
Director of the Center for Brain Health. His group was the first to
demonstrate with CT and later with MRI scans that the hippocampus, a
sea-horse shaped area of the brain associated with memory and
learning, diminishes in size as Alzheimer’s disease progresses from
mild cognitive impairment to full-blown dementia.
Yet until now there has been no
reliable way to accurately and quickly measure the hippocampal area
of the brain on a PET scan. The hippocampus is small and its size
and shape are affected greatly in individuals with Alzheimer’s,
making it difficult to sample this region. HipMask is a sampling
technique that uses MRI to anatomically probe the PET scan.
MRI relies on electromagnetic
energy to excite water molecules in the brain to create an
anatomical map of the brain. The MRI was used in the study to
determine the total volume of the hippocampus and then to define
that portion (namely the HipMask) that was shared by all persons
regardless of their disease status. PET employs radioactively
labeled glucose to show the brain at work and the HipMask was
applied to these scans to derive estimates of the hippocampal
glucose metabolism.
The researchers followed 53
healthy, normal subjects between the ages of 54 and 80 for at least
9 years and in some cases for as long as 24 years. All subjects
received two FDG-PET scans -- one at baseline and a follow-up after
3 years. Thirty individuals had a second follow-up scan after
another seven years. Altogether there were 136 PET scans.
The researchers applied the
HipMask to all 136 scans. The results showed that hippocampal
glucose metabolism, as determined by the HipMask, was significantly
reduced 15% to 40% on the first scan, compared to controls, of those
25 individuals who would later experience cognitive decline related
to either mild cognitive impairment or to Alzheimer’s. The
researchers found that the baseline hippocampal glucose metabolism
was the only brain or clinical measure that predicted the future
cognitive decline.
“Right now, we can show with great accuracy who will develop
Alzheimer’s nine years in advance of symptoms, and our projections
suggest we might be able to take that out as far as 15 years,” says
Dr. de Leon, whose longitudinal study is funded by the National
Institutes of Health (NIH).
“Our basic results will need to be
replicated in other studies and expanded to include PET data from
diverse patient groups,” adds Dr. De Leon. “But we’re confident this
is a strong beginning, demonstrating accurate detection of early
Alzheimer’s disease. Now we have a better tool to examine disease
progression, and we anticipate this might open some doors to
prevention treatment strategies.”
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