"We have known that exercise improves blood sugar and that it helps prevent age-related memory loss," says lead researcher Scott Small, MD, of Columbia University Medical Center. "In this study, we were able to show the specific area of the brain that is impacted by rising blood sugar."
Blood Sugar and Memory
Focusing on the hippocampus -- the area of the brain associated with memory and learning -- Small and colleagues previously identified a section that was most associated with age-related memory decline.
In their newly published study, the researchers looked at how this area, known as the dentate gyrus, is affected by changes typically seen with aging, such as rising cholesterol, body weight, and blood sugar.
Human and animal imaging studies confirmed that rising blood sugar was the only change directly associated with decreased activity in the dentate gyrus.
Because blood sugar levels tend to rise with age, the finding suggests that monitoring and taking steps to lower blood sugar as we grow older may be an important strategy for preventing age-related cognitive decline for everyone, not just people with diabetes, Small tells WebMD.
The study was funded by the National Institute on Aging, the American Diabetes Association, and the McKnight Brain Research Foundation. It appears in the December issue of the journal Annals of Neurology.
"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," Small says in a news release.
Exercise Lowers Blood Sugar
Because exercise improves the ability of the muscles to process glucose, it makes sense that it helps protect cognitive function as we age, Small says.
Linda Nichol, PhD, of the National Institute on Aging, tells WebMD that the research may help explain why diabetic people are at increased risk of developing Alzheimer's disease.
She says studies are under way to determine if drugs that regulate blood sugar can help slow cognitive declines in people with early evidence of the disease.
It is far too soon to say if people who don't have diabetes might benefit from taking the drugs as they get older, she says.
"We already know that physical exercise can help people stay cognitively sharp as they age," she adds. "This study may help explain why."