Physical Exercise Improves Memory
Two recent experiments, one involving people and the other mice, suggest that regular exercise improves memory. However, different types of exercise affect the brain differently.
In the 1990s scientists at the Salk Institute in La Jolla, Calif., discovered that exercise “bulks up” the brain. In groundbreaking experiments, they showed that mice given access to running wheels produced far more cells in an area of the brain controlling memory than animals that didn’t run. The exercised animals then performed better on memory tests. Since then, scientists have been working to understand precisely how, at a molecular level, exercise improves memory, as well as whether all types of exercise, including weight training, are beneficial.
In one recent study, published in The Journal of Aging Research, scientists recruited dozens of women ages 70 to 80 with mild cognitive impairment, which is a recognized risk factor for increasing dementia.
Earlier research had found that after weight training, older women with mild cognitive impairment improved their associative memory, or the ability to recall things in context — a stranger’s name and how you were introduced, for instance.
Now the scientists wanted to look at both other types of memory and at endurance exercise as well. So they randomly assigned their volunteers to six months of supervised exercise. Some of the women lifted weights twice a week. A second group walked briskly. And the third group, who acted as a control measure, skipped endurance exercise and instead stretched and toned.
At the start and end of the six months, the women completed tests of verbal and spatial memory, both of which deteriorate with age. This loss is even more noticeable with mild cognitive impairment. In this study, after six months, the women in the stretching toning group actually scored worse on the memory tests than they had at the start of the study.
But the women who had exercised, either by walking or weight training, performed better on almost all of the cognitive tests.
But there were differences. While both exercise groups improved almost equally on tests of spatial memory, the women who had walked showed greater gains in verbal memory than the women who had lifted weights. The authors concluded that endurance training and weight training might have different physiological effects within the brain and cause improvements in different types of memory.
That idea correlates well with the results of another recent study of exercise and memory, in which lab rats either ran on wheels or “lifted weights”. Specifically, the researchers taped weights to the animals’ tails and had them repeatedly climb little ladders to simulate resistance training.
After six weeks, the animals in both exercise groups scored better on memory tests than they had before they trained. Even more interesting is that scientists found the runners’ brains had increased levels of a protein known as BDNF, or brain-derived neurotrophic factor, which support existing neurons and encourages the creation of new brain cells. The rat weight-trainers’ brains, on the other hand, did not show increased levels of BDNF.
The tail trainers, however, had significantly higher levels of another protein, an insulin-like growth factor, than the runners did. This substance, too, promotes cell division and growth and probably helps fragile newborn neurons survive.
What all of this new research suggests is that it’s probably best to incorporate both aerobic and resistance training. It seems that each type of exercise selectively targets different aspects of cognition, probably by promoting the release of different proteins.
But whether you choose to focus solely on aerobic or resistance training, at least in terms of memory improvements, the differences in the effects of each type of exercise were subtle. However, the effects of exercise — any exercise — on overall cognitive function are profound. Regular exercise improves memory.