Researchers Link Blood Sugar to Normal Cognitive Aging

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Source: Columbia University Medical Center

Released: Mon 15-Dec-2008, 12:20 ET

Embargo expired: Tue 30-Dec-2008, 00:00 ET

Researchers Link Blood Sugar to Normal Cognitive Aging

http://www.newswise.com/articles/view/547433/?sc=dwhn

Newswise — Maintaining blood sugar levels, even in the absence of

disease, may be an important strategy for preserving cognitive health,

suggests a study published by researchers at Columbia University Medical

Center (CUMC). The study appeared in the December issue of ls of

Neurology.

Senior moments, also dubbed by New York Times Op-Ed columnist

as being " hippocampically challenged,” are a normal part of

aging. Such lapses in memory, according to this new research, could be

blamed, at least in part, on rising blood glucose levels as we age. The

findings suggest that exercising to improve blood sugar levels could be

a way for some people to stave off the normal cognitive decline that

comes with age.

" This is news even for people without diabetes since blood glucose

levels tend to rise as we grow older. Whether through physical exercise,

diet or drugs, our research suggests that improving glucose metabolism

could help some of us avert the cognitive slide that occurs in many of

us as we age, " reported lead investigator A. Small, M.D.,

associate professor of neurology in the Sergievsky Center and in the

Taub Institute for Research on Alzheimer’s Disease and the Aging Brain

at Columbia University Medical Center.

Although it is widely known that the early stages of Alzheimer’s disease

cause damage to the hippocampus, the area of the brain essential for

memory and learning, studies have suggested that it is also vulnerable

to normal aging. Until now, the underlying causes of age-related

hippocampal dysfunction have remained largely unknown.

Previously, using high-resolution brain imaging, Dr. Small and his

colleagues discovered that decreasing brain function in one area of the

hippocampus, called the dentate gyrus, is a main contributor of normal

decline in memory as we age.

In this new study, funded by the National Institute on Aging (NIA), the

American Diabetes Association and the McKnight Brain Research

Foundation, the researchers mapped out the specific areas of the

hippocampus impacted by late-life diseases like diabetes and stroke.

“This research used imaging in both human volunteers and in animal

models to help us better understand the basic mechanisms behind

hippocampal dysfunction in the aged,” said Dr. Marcelle

on-Bogorad, NIA Division of Neuroscience director. “While more

research is needed into the complex interaction of late-life disease and

how it may affect the hippocampus, this new study is part of an ongoing

effort to identify specific areas where interventions might preserve

cognitive health.”

This new study looked at measures that typically change during aging,

like rising blood sugar, body mass index, cholesterol and insulin

levels. The research found that decreasing activity in the dentate gyrus

only correlated with levels of blood glucose.

“Showing for the first time that blood glucose selectively targets the

dentate gyrus is not only our most conclusive finding, but it is the

most important for 'normal' aging- that is hippocampal dysfunction that

occurs in the absence of any disease states. There have been many

proposed reasons for age-related hippocampal decline; this new study

suggests that we may now know one of them, " said Dr. Small.

Additional animal studies helped confirm the relationship between

glucose and dentate gyrus activity; the researchers found the same

association in aging rhesus monkeys and in mice.

“Beyond the obvious conclusion that preventing late-life disease would

benefit the aging hippocampus, our findings suggest that maintaining

blood sugar levels, even in the absence of diabetes, could help maintain

aspects of cognitive health. More specifically, our findings predict

that any intervention that causes a decrease in blood glucose should

increase dentate gyrus function and would therefore be cognitively

beneficial,” said Dr. Small.

The new findings also suggest that one way in which physical exercise

could improve memory is via lowering glucose levels. Dr. Small’s

previous imaging studies in humans and in mice have documented that

among all hippocampal subregions, physical exercise causes an

improvement in dentate gyrus function.

“By improving glucose metabolism, physical exercise also reduces blood

glucose. It is therefore possible that the cognitive enhancing effects

of physical exercise are mediated, at least in part, by the beneficial

effect of lower glucose on the dentate gyrus. Whether with physical

exercise, diet or through the development of potential pharmacological

interventions, our research suggests that improving glucose metabolism

could be a clinically viable approach for improving the cognitive slide

that occurs in many of us as we age,” concluded Dr. Small.

With increasing longevity and the aging of the baby boom population,

cognitive decline has emerged as a major health care crisis and concern.

This study was built upon an extensive, ongoing epidemiological imaging

study -- under the direction of Mayeux, M.D., M.S.-- that

evaluated 240 healthy elders in Manhattan. Dr. Mayeux is professor of

neurology, psychiatry, and epidemiology and co-director of the Taub

Institute for Research on Alzheimer’s Disease and the Aging Brain at CUMC.

Dr. Small led a team of investigators who published the first article

using fMRI to investigate Alzheimer’s disease and memory decline in the

aging population. More recently, Dr. Small has pioneered a novel

high-resolution application of fMRI, which can be used to investigate

physiologic dysfunction in both mouse models of disease and in human

patients. By being able to investigate patients and animal models in

parallel studies, this new application will help researchers learn more

about diseases of the brain.

Other authors of the ls of Neurology study are: Wu, Adam M.

Brickman, Luchsinger, Ferrazano, Paola Pichiule, Mistuhiro

Yoshita, Truman Brown, DeCarli, Carol , Mayeux and

J. Vannucci.

The Taub Institute for Research on Alzheimer’s Disease and the Aging

Brain at Columbia University Medical Center is a multidisciplinary group

that has forged links between researchers and clinicians to uncover the

causes of Alzheimer’s, Parkinson’s and other age-related brain diseases

and discover ways to prevent and cure these diseases. It has partnered

with the Gertrude H. Sergievsky Center at Columbia University Medical

Center which was established by an endowment in 1977 to focus on

diseases of the nervous system. The Center integrates traditional

epidemiology with genetic analysis and clinical investigation to explore

all phases of diseases of the nervous system. For more information about

these centers visit: http://www.cumc.columbia.edu/dept/taub/

http://www.cumc.columbia.edu/dept/sergievsky/

Columbia University Medical Center provides international leadership in

basic, pre-clinical and clinical research, in medical and health

sciences education, and in patient care. The medical center trains

future leaders and includes the dedicated work of many physicians,

scientists, public health professionals, dentists, and nurses at the

College of Physicians and Surgeons, the Mailman School of Public Health,

the College of Dental Medicine, the School of Nursing, the biomedical

departments of the Graduate School of Arts and Sciences, and allied

research centers and institutions. Established in 1767, Columbia's

College of Physicians and Surgeons was the first institution in the

country to grant the M.D. degree and is among the most selective medical

schools in the country. Columbia University Medical Center is home to

the largest medical research enterprise in New York City and state and

one of the largest in the United States. For more information, please

visit www.cumc.columbia.edu.

--

ne Holden, MS, RD

" Ask the Parkinson Dietitian " http://www.parkinson.org/

" Eat well, stay well with Parkinson's disease "

" Parkinson's disease: Guidelines for Medical Nutrition Therapy "

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