Researchers here add more data to the known correlations between specific measures of fitness and cognitive function in later life. There are any number of potential mechanisms linked to exercise that might explain a slower age-related decline in memory and learning capacity in people who better maintain physical fitness, such as the state and activity of the immune system in the brain, as well as mitochondrial function, and vascular integrity. Pinning down specific contributions and the relative importance between mechanisms is, of course, a challenge.
Older adults who experience good cardiac fitness may be also keeping their brains in good shape as well. In what is believed to be the first study of its kind, older adults who scored high on cardiorespiratory fitness (CRF) tests performed better on memory tasks than those who had low CRF. Further, the more fit older adults were, the more active their brain was during learning. Healthy young (18-31 years) and older adults (55-74 years) with a wide range of fitness levels walked and jogged on a treadmill while researchers assessed their cardiorespiratory fitness by measuring the ratio of inhaled and exhaled oxygen and carbon dioxide. These participants also underwent MRI scans which collected images of their brain while they learned and remembered names that were associated with pictures of unfamiliar faces.
The researchers found that older adults, when compared to younger adults, had more difficulty learning and remembering the correct name that was associated with each face. Age differences in brain activation were observed during the learning of the face-name pairs, with older adults showing decreased brain activation in some regions and increased brain activation in others. However, the degree to which older adults demonstrated these age-related changes in memory performance and brain activity largely depended on their fitness level. In particular, high fitness older adults showed better memory performance and increased brain activity patterns compared to their low fitness peers. The increased brain activation in the high fitness older adults was observed in brain regions that show typical age-related decline, suggesting fitness may contribute to brain maintenance. Higher fitness older adults also had greater activation than young adults in some brain regions, suggesting that fitness may also serve a compensatory role in age-related memory and brain decline.