Alzheimer's, Dementia & Mental Health
Obese Senior Citizens Face Increased Risk of
Alzheimer’s Due to Loss of Brain Tissue
Obese elderly had lost brain tissue in the frontal
and temporal lobes, areas of the brain critical for planning and memory,
and other areas
Aug. 25, 2009 – The latest bad news for obese and
overweight senior citizens comes from a new study of seniors age 70 and
older. It found the brains of those that were two fat, had less brain
tissue than normal weight seniors, which puts them a greater risk of
Alzheimer’s and other diseases of the brain.
Obesity is on a rampage, with the World Health
Organization pegging the numbers at more than 300 million worldwide,
with a billion more overweight. With obesity comes the increased risk
for cardiovascular disease, Type II diabetes, and hypertension.
In the current online edition of the journal
Human Brain Mapping, Paul Thompson, senior author and a UCLA
professor of neurology, and lead author Cyrus A. Raji, a medical student
at the University of Pittsburgh School of Medicine, and colleagues
compared the brains of people who were obese, overweight, and of normal
weight, to see if they had differences in brain structure; that is, did
their brains look equally healthy.
They found that obese people had 8 percent less
brain tissue than people with normal weight, while overweight people had
4 percent less tissue. According to Thompson, who is also a member of
UCLA's Laboratory of Neuro Imaging, this is the first time anyone has
established a link between being overweight and having what he describes
as "severe brain degeneration."
"That's a big loss of tissue and it depletes your
cognitive reserves, putting you at much greater risk of Alzheimer's and
other diseases that attack the brain," said Thompson. "But you can
greatly reduce your risk for Alzheimer's, if you can eat healthily and
keep your weight under control."
The researchers used brain images from an earlier
study called the Cardiovascular Health Study Cognition Study. Scans were
selected of 94 elderly people in their 70s who were healthy not
cognitively impaired—five years after the scan was taken.
To define the weight categories, they used the Body
Mass Index (BMI), the most widely used measurement for obesity.
Normal weight people were defined as having a BMI
between 18.5-25; overweight people between 25-30, and obese people
greater than 30.
The researchers then converted the scans into
detailed three-dimensional images using tensor-based morphometry, a
neuroimaging method that offers high resolution mapping of anatomical
differences in the brain.
In looking at both grey matter and white matter of
the brain, they found that the people defined as obese had lost brain
tissue in the frontal and temporal lobes, areas of the brain critical
for planning and memory, and in the anterior cingulate gyrus (attention
and executive functions), hippocampus (long term memory) and basal
ganglia (movement).
Overweight people showed brain loss in the basal
ganglia, the corona radiata, white matter comprised of axons, and the
parietal lobe (sensory lobe).
"The brains of obese people looked 16 years older
than the brains of those who were lean, and in overweight people looked
eight years older," says Thompson.
"It seems that along with increased risk for health
problems such as type 2 diabetes and heart disease, obesity is bad for
your brain: we have linked it to shrinkage of brain areas that are also
targeted by Alzheimer's," said Pittsburgh's Raji. "But that could mean
exercising, eating right and keeping weight under control can maintain
brain health with aging and potentially lower the risk for Alzheimer's
and other dementias."
The research was funded by the National Institute
on Aging, National Institute of Biomedical Imaging and Bioengineering,
National Center for Research Resources, and the American Heart
Association. Other authors included April J. Ho, Neelroop N. Parikshak,
Xue Hua, Alex D. Leow, Arthur W. Toga, all of UCLA, and James T. Becker,
Oscar L. Lopez, and Lewis H. Kuller, all of Pittsburgh.
The UCLA Department of Neurology encompasses more
than a dozen research, clinical and teaching programs, and ranks first
among its peers nationwide in National Institutes of Health funding. For
more information, see
http://neurology.medsch.ucla.edu/.
