Elderly people who are overweight or obese tend to have less tissue in certain areas of the brain, suggesting they might be at greater risk for dementia, Alzheimer's disease and other cognition-impairing conditions, according to researchers at the University of Pittsburgh and the University of California Los Angeles.

Based on data gathered from brain scans conducted for the Pittsburgh-based Cardiovascular Health Study, the researchers found that people age 70 or older and overweight, meaning with a body mass index from 25 to 30, had 4 percent less tissue in the frontal lobes of the brain than their normal-weight peers. Those who were obese, meaning a body mass index greater than 30, had 8 percent less tissue in the same regions, which are crucial for cognitive tasks such as memory and planning, said lead investigator Cyrus A. Raji, Ph.D., who is in the combined M.D./Ph.D. program at Pitt's School of Medicine.

"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 also are targeted by Alzheimer's," Raji said. "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 94 participants in the study, which was published this month in the online version of Human Brain Mapping, were all cognitively normal at the time their brain imaging was done and five years later. New, sophisticated methods of computer analysis were applied to the high-resolution scans, allowing 3-dimensional mapping of brain structures to reveal patterns in volume differences that were not apparent in previous research.

The team 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).

"This is the first time anyone has created brain maps proving the link between being overweight and severe brain degeneration," said senior investigator Paul M. Thompson, Ph.D., professor, Department of Neurology, UCLA School of Medicine. "The brains of obese people looked 16 years older than the brains of those who were lean, and the brains of overweight people looked eight years older."

The research was funded by grants from the National Institute on Aging, the National Institute of Biomedical Imaging and Bioengineering, the National Center for Research Resources and the American Heart Association.

Co-authors include Oscar L. Lopez, M.D., professor, Department of Neurology, and James T. Becker, Ph.D., professor, Department of Psychiatry, both of the School of Medicine, and Lewis H. Kuller, M.D., Dr.P.H., Graduate School of Public Health, all of the University of Pittsburgh; April J. Ho, B.S., Neelroop N. Parikshak, B.S., Xue Hua, Ph.D., Alex. D. Leow, M.D., Ph.D., and Arthur W. Toga, Ph.D., all of the Department of Neurology, UCLA School of Medicine.

Source
University of Pittsburgh School of Medicine

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