Low Blood Sugar Levels May Help Protect Against Memory Loss

People with elevated blood sugar, even those without diabetes, have less brain activity.

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Physical exercise helps lower blood glucose, and that might protect memory, according to an intriguing new brain imaging study by researchers at Columbia University Medical Center. They found that older people with elevated blood sugar have less activity in the dentate gyrus, a brain region key to memory. That difference holds true even if they don't have diabetes.

Blood glucose levels tend to rise as people get older, and about 40 percent of people 65 and older have age-related memory impairment. Neurons degrade over time, and brain parts communicate less well. Visual and verbal memory, executive control, and multitasking are often affected. The new study, published in the December Annals of Neurology, hints that rising blood glucose might be a cause of age-related memory loss. Controlling glucose, through diet, medication, or exercise, could not only reduce the risk of diabetes but preserve brain function. This news also helps explain why the best way to stay mentally sharp throughout life is to keep moving. People who are active do better on tests of executive control, which encompasses skills involved in scheduling, planning, and memory. Physically active adults are also less likely to have Alzheimer's in old age. And children who exercise as little as 10 minutes did better at problem-solving in school.

Mental exercise seems to help, too, although the benefits have not been as robust as for physical exercise. The brain grows new neuronal connections in response to mental challenges, and people who have demanding jobs or hobbies maintain memory better and longer. Most "brain training" programs on the market have not been clinically tested, and those that have tend to improve performance on one specific skill, such as memorizing a list. However, a new study in the December Psychology and Aging by Art Kramer, a psychologist at the University of Illinois, found that adults who played Rise of Nations—a video game that requires them to establish cities, build infrastructure, and expand national boundaries—improved their multitasking and working memory after 23.5 hours playing the game.

Much has been made of supplements like ginkgo biloba, but a study in last November's Journal of the American Medical Association found that ginkgo didn't slow the progression of dementia. Instead, epidemiological studies show that adults who eat reduced-fat diets are less likely to get Alzheimer's. Healthy fats like olive oil and fish oils may be protective, too, as well as foods high in antioxidants, such as berries and leafy green veggies. UCLA's Center of Aging is investigating curcumin, a compound found in the spice turmeric, which may have anti-inflammatory properties. Curry, anyone?

"It's very common to become aware of changes in memory," says Gary Small, a psychiatrist who directsthe center at UCLA. If those changes have you worried, Small says, by all means go see your doctor. A 20-minute memory test can reveal if there's something seriously amiss and will most likely relieve anxiety.