0 Aerobic exercise improves memory brain function and physical fitness

A new study conducted by researchers at the Center for BrainHealth at The University of Texas at Dallas published online in the open-access journal Frontiers in Aging Neuroscience found that engaging in a physical exercise regimen helps healthy aging adults improve their memory, brain health and physical fitness. This finding is significant considering that among adults 50 and older, "staying mentally sharp" outranks social security and physical health as the top priority and concern in the United States.

"Science has shown that aging decreases mental efficiency and memory decline is the number one cognitive complaint of older adults," said Sandra Bond Chapman, Ph.D., founder and chief director of the Center for BrainHealth, Dee Wyly Distinguished University Chair and lead author of the paper. "This research shows the tremendous benefit of aerobic exercise on a persons memory and demonstrates that aerobic exercise can reduce both the biological and cognitive consequences of aging."

For the study, sedentary adults ages 57-75 were randomized into a physical training or a wait-list control group. The physical training group participated in supervised aerobic exercise on a stationary bike or treadmill for one hour, three times a week for 12 weeks. Participants cognition, resting cerebral blood flow, and cardiovascular fitness were assessed at three time points: before beginning the physical exercise regimen, mid-way through at 6 weeks, and post-training at 12 weeks.

"By measuring brain blood flow non-invasively using arterial spin labeling (ASL) MRI, we can now begin to detect brain changes much earlier than before," said Sina Aslan, Ph.D., founder and president of Advance MRI and collaborator on the study. "One key region where we saw increase in brain blood flow was the anterior cingulate, indicating higher neuronal activity and metabolic rate. The anterior cingulate has been linked to superior cognition in late life."

Exercisers who improved their memory performance also showed greater increase in brain blood flow to the hippocampus, the key brain region affected by Alzheimers disease. Chapman pointed out that, using noninvasive brain imaging techniques, brain changes were identified earlier than memory improvements, implicating brain blood flow as a promising and sensitive metric of brain health gains across treatment regimens.

"Physical exercise may be one of the most beneficial and cost-effective therapies widely available to everyone to elevate memory performance," says Dr. Chapman. "These findings should motivate adults of all ages to start exercising aerobically."

Chapman cautioned that while physical exercise is associated with a selective or regional brain blood flow, it did not produce a change in global brain blood flow.

"In another recent study, we have shown that complex mental training increases whole brain blood flow as well as regional brain blood flow across key brain networks," Chapman said. "The combination of physical and mental exercise may be the best health measures to improve overall cognitive brain health. We have just begun to test the upper boundaries of how we can enhance our brains performance into late life. To think we can alter and improve the basic structure of the mature brain through aerobic exercise and complex thinking should inspire us to challenge our thinking and get moving at any age."

0 Overeating impairs brain insulin function can lead to diabetes and obesity

New research from Mount Sinai School of Medicine sheds light on how overeating can cause a malfunction in brain insulin signaling, and lead to obesity and diabetes. Christoph Buettner, MD, PhD, Associate Professor of Medicine (Endocrinology, Diabetes and Bone Disease) and his research team found that overeating impairs the ability of brain insulin to suppress the breakdown of fat in adipose tissue.

In previous research Dr. Buettners team established that brain insulin is what suppresses lipolysis, a process during which triglycerides in fat tissue are broken down and fatty acids are released. When lipolysis is unrestrained, fatty acid levels are elevated, which can initiate and worsen obesity and type 2 diabetes. The current study is published online in The Journal of Biological Chemistry. The first study was published in the February 2, 2011 issue of Cell Metabolism.

"We are interested in understanding why people who eat too much eventually develop diabetes. Our recent studies suggest that once you overeat, your brain develops insulin resistance. Since brain insulin controls lipolysis in adipose tissue by reducing sympathetic nervous system outflow to adipose tissue, brain insulin resistance causes increased spillage of fatty acids from adipose tissue into the blood stream," said Dr. Buettner.

Increased fatty acids induce inflammation and that, in turn, can further worsen insulin resistance, which is the core defect in type 2 diabetes. Fatty acids also increase glucose production in the liver which raises blood glucose levels, Dr. Buettner explained. "Its a vicious cycle and while we knew that this can begin with overeating, this study shows that it is really the brain that is harmed first which then starts the downward spiral."

In this study, researchers fed rats a high-fat diet comprised of 10 percent lard for three consecutive days. This increased their daily caloric intake by up to 50 percent compared to the control rats that were fed a regular low fat diet. The researchers then infused a tiny amount of insulin into the brains of both groups of rats that they had shown in earlier studies to suppress release of glucose from the liver and fatty acids from fat tissue. They found that overeating impaired the ability of brain insulin to suppress glucose release from the liver and lipolysis in fat tissue. Similarly, short-term overeating in humans is known to produce comparable insulin resistance which could be explained by brain insulin resistance.

"When you overeat, your brain becomes unresponsive to these important clues such as insulin, which puts you on the road to diabetes. We believe that what happens in rats also happens in humans" said Dr. Buettner.

Dr. Buettners team plans to investigate methods of improving brain insulin function that could restrain lipolysis and improve insulin resistance.