A new study suggests maintaining normal blood sugar levels as we age may protect against diabetes and prevent age-related memory loss.
Spikes in blood sugar levels can take a toll on memory by affecting the dentate gyrus, a region of the brain within the hippocampus where memories are stored.
The effects can be detected even when blood sugar levels, or glucose, are only slightly elevated, a finding that may explain normal age-related cognitive decline, since glucose regulation declines with age, said researchers.
“If we determine this is normal age-related cognitive decline, then it affects all of us,” said Dr. Scott Small, lead author and professor of neurology at Columbia University Medical Center. The body’s ability to regulate glucose begins to decline by about the third decade of life.
For the study, researchers used high resolution brain imaging to chart brain regions in 240 elderly participants. They found a connection between elevated blood glucose levels and reduced cerebral blood volume, or blood flow, in the dentate gyrus, a sign of reduced metabolic activity and function in that region of the brain.
By controlling blood sugar levels in monkeys and rodents, researchers attempted to confirm a cause-and-effect relationship between spikes in glucose and reduced blood volume, Dr. Small said.
Previous studies have found that physical activity lowers the risk of cognitive decline and shown that diabetes increases the risk of dementia. Earlier studies also found a connection between Type 2 diabetes and dysfunction in the dentate gyrus.
Regular physical activity, even light exercise, can offset the potentially negative effects of Type 2 diabetes on cognitive function, says Sheri Colberg-Ochs, an associate professor of exercise science at Old Dominion University in Norfolk, Va. While it is not entirely clear what the mechanism is, she said it may have something to do with the effect of insulin.
“The findings allow for a better understanding of which region of the hippocampus is most likely to be affected by poorly-controlled diabetes,” she said.
The research from this study may help explain why diabetic people are at a greater risk of developing Alzheimer's disease, Linda Nichol, PhD, of the National Institute on Aging, tells WebMD.
"We know physical exercise can help people to stay cognitively sharp as they age," she adds. "And, this study may help explain why."
The study, conducted by researchers at Columbia University Medical Center and funded in part by the American Diabetes Association and the National Institute on Aging, appears in the December issue of Annals of Neurology. #