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New evidence published in Mayo Clinic Proceedings from the German Center for Neurodegenerative Diseases suggests a positive association between exercise and gray matter volume in regions of the brain already linked to cognitive decline and aging.
Fifty million people are affected by dementia worldwide. Consequently, there is a significant amount of research focused on dementia risk reduction, treatment, and cure. To date, the National Academies of Sciences, the Lancet Commission, and the World Health Organization have all recognized exercise as a way of slowing cognitive impairment. This study contributes to the growing body of evidence connecting cardiorespiratory fitness, or any exercise that gets your heart pumping, to brain health. While there have been several smaller studies supporting an association between exercise and brain health, this study is unique because of its large representative population size.
Researchers examined two independent cohorts that included 2,013 adults from northeastern Germany aged 21 to 84. Peak oxygen uptake and other cardiorespiratory fitness standards were measured while participants used an exercise bike. Magnetic resonance imaging (MRI) coupled with whole-brain voxel-based morphometry monitored structural changes in gray matter, white matter, and total brain volume as a result of the exercise. Gray brain matter consists of cell bodies while white matter mainly consists of extensions or filaments called axons from the cells. A high peak oxygen uptake was associated with increased gray matter brain volumes.
Structural MRI data revealed that cardiorespiratory fitness was positively associated with increased gray matter and total brain volumes in specific regions of the brain relating to cognitive function, including parts of the temporal, frontal, and cerebellar regions. A Mayo Clinic editorial written by three medical experts asserts that some of the brain regions identified in the study align with regions of the brain previously found to be related to aging, cognitive impairment, and Alzheimer’s disease. The editorial, however, emphasizes that it is not yet known if these regional associations have any definitive impact on Alzheimer’s disease. Moreover, the editorial notes that the brain regions identified are not primarily responsible for motor-related functions, which provides indirect evidence that cardiorespiratory fitness not only improves physical conditioning but can also influence cognitive function. Changes in white matter were not observed, but perhaps other imaging techniques are needed to assess any associations. The data also suggests that the effect of cardiorespiratory fitness may be stronger in individuals aged 45 years and older, suggesting it may never be too late to gain the beneficial effects of exercise.
Although the evidence for an association between cardiorespiratory fitness, gray matter, and certain brain structures is promising and unique, the association cannot be deemed causative. It is unclear whether cardiorespiratory fitness caused gray matter to increase or if individual innate differences in brain volumes resulted in stronger cardiorespiratory fitness. It is also unclear how the participant’s regular exercise habits affect the findings. Long-term studies are required in the future to assess causation; these studies may be costly and logistically challenging to conduct but will provide another important piece of the puzzle to understanding how exercise affects brain health.
Wittfeld, Katharina et al. (2020). Cardiorespiratory Fitness and Gray Matter Volume in the Temporal, Frontal, and Cerebellar Regions in the General Population. Mayo Clinic Proceedings, Volume 95, Issue 1, 44 – 56.
(n.d.). Keep exercising: New study finds it’s good for your brain’s gray matter. Retrieved from https://www.eurekalert.org/pub_releases/2020-01/mc-eak123019.php.
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