Many studies suggest that daily activities like walking may help keep the memory sharp. Now a growing number of studies show that a daily walk can lead to positive physical changes in the brain as well.
Psychologists report that older adults who walked three times a week had enlargements in the hippocampus, an area of the brain critical for memory. The hippocampus tends to shrink in older adults, setting the stage for memory loss that in some cases leads to Alzheimer’s disease. But in seniors who remain physically fit, the hippocampus tends to be larger than those who are sedentary. Active seniors, as a group, also tend to have a lower risk of memory problems and Alzheimer’s disease.
The brain changes were small: the hippocampus increased in volume by 2 percent. But that enlargement translates into one to two years of brain wasting that would occur from normal aging. The findings were published in the Proceedings of the National Academy of Science.
In the study, 120 men and women who were, on average, in their mid-60s were assigned to one of two groups. Half walked around a track for three times a week, along with warm-up and cool-down exercises, for up to 40 minutes at a stretch. The aerobic routines were designed to increase heart rate. The others did less aerobic stretching and toning exercises, including yoga and resistance training with bands.
A year later, brain scans revealed that the walkers had expansion in the hippocampus. In the others, the hippocampus shrunk by 1 to 2 percent. Both groups had improvements in their spatial memory, which helps us to do things like navigate traffic and find our way through the store. But it improved more in the walking group.
Last year, researchers showed that walking six to nine miles a week may help ward off the memory loss of aging. And other studies have suggested that activities like walking or ballroom dancing may help to prevent the onset of Alzheimer’s and other types of dementia or help those in the early stages of the disease. In mice that have been bred to develop a disease that resembles Alzheimer’s, vigorous activity helped diminish the buildup of the plaques and in the brains of humans with the disease.
In the current study, the exercise was more modest, only 40 minutes or less a few times a week. Yet the benefits were significant.
"We think of the atrophy of the hippocampus in later life as almost inevitable," said Kirk Erickson, the lead author and a professor of psychology at the University of Pittsburgh.
Art Kramer, another author and psychologist at the University of Illinois, added, "The results of our study are particularly interesting in that they suggest that even modest amounts of exercise by sedentary older adults can lead to substantial improvements in memory and brain health."
Kirk I. Erickson, Michelle W. Voss, Ruchika Shaurya Prakash, et al: “Exercise Training Increases Size of Hippocampus and Improves Memory.” Proceedings of the National Academy of Sciences. January 31, 2011.