Regular moderate exercise is well known and well established to be beneficial to long term health in many ways. Lack of exercise is actively harmful to long term health, on the other hand. Researchers here add another correlation between exercise and brain health, in that the size of functional areas of the brain is larger in those who do exercise, providing more of a protective buffer against the onset of neurodegeneration and cognitive decline.
Which of the numerous mechanisms connecting exercise and brain function are most important in this effect remains an open question, though the data in this study suggests that increased blood flow is the dominant aspect. Exercise does boost blood flow to the brain, but also upregulates BDNF expression, which in turn increases neurogenesis, the creation of new neurons. Balancing the relative importance of these and other mechanisms is challenging given the complexity of the aging, biology, and the brain.
Researchers examined data on exercise and the brain for 2,550 participants of the Rhineland Study. “We were able to show that physical activity had a noticeable effect on almost all brain regions investigated. Generally, we can say that the higher and more intense the physical activity, the larger the brain regions were, either with regard to volume or cortical thickness. In particular, we observed this in the hippocampus, which is considered the control center of memory. Larger brain volumes provide better protection against neurodegeneration than smaller ones.” However, the dimensions of the brain regions do not increase linearly with physical activity. The research team found the largest, almost sudden volume increase when comparing inactive and only moderately physically active study participants – this was particularly evident in older individuals over the age of 70.
“In principle, this is very good news – especially for those who are reluctant to exercise. Our study results indicate that even small behavioral changes, such as walking 15 minutes a day or taking the stairs instead of the elevator, may have a substantial positive effect on the brain and potentially counteract age-related loss of brain matter and the development of neurodegenerative diseases. In particular, older adults can already profit from modest increases of low intensity physical activity.” Young and somewhat athletic subjects who usually engaged in moderate to intense physical activity also had relatively high brain volumes. However, in even more active subjects, these brain regions were slightly larger. Also here it showed: the more active, the greater the effect, although at high levels of physical activity, the beneficial effects tended to level off.
To characterize the brain regions that benefited most from physical activity, the research team searched databases for genes that are particularly active in these brain areas. “Mainly, these were genes that are essential for the functioning of mitochondria, the power plants of our cells.” This means that there are particularly large numbers of mitochondria in these brain regions. Mitochondria provide our body with energy, for which they need a lot of oxygen. “Compared to other brain regions, this requires increased blood flow. This is ensured particularly well during physical activity, which could explain why these brain regions benefit from exercise.”