A new study, published in the Mayo Clinic Proceedings, provides evidence of an association between cardiorespiratory fitness — which refers to the ability of the circulatory and respiratory systems to supply oxygen during physical activity — and brain health, particularly in gray matter and total brain volume.
Wittfeld et al support the hypothesis that higher cardiorespiratory fitness is associated with larger brain volumes in several brain regions that are not primarily connected to motor-related functions. Image credit: Mabel Amber.
“Countries worldwide are facing aging societies. And it is essential to identify strategies to slow brain aging and help preserve brain structure and functionality in older individuals,” said lead author Dr. Katharina Wittfeld of the German Center for Neurodegenerative Disease and colleagues.
“Cardiorespiratory fitness is considered a key factor reducing mortality and morbidity risks, several cancers, and possibly brain atrophy.”
“Well-powered randomly selected population samples with deeply phenotyped measures of the brain are necessary to provide robust evidence for an effect of cardiorespiratory fitness on gray matter and white matter volume on a high spatial resolution analyses.”
The study involved 2,103 adults (21-84 years old) from two independent population-based cohorts in Germany.
Cardiorespiratory fitness was measured using peak oxygen uptake, oxygen uptake at the anaerobic threshold, and maximal power output from cardiopulmonary exercise testing on a bicycle ergometer.
MRI brain data were analyzed with adjustment for age, sex, education, smoking, body weight, systolic blood pressure, glycated hemoglobin level, and intracranial volume.
The researchers found that increases in peak oxygen uptake were strongly associated with increased gray matter volume.
Results of the voxel-based morphometry (VBM) analyses of peak oxygen uptake (VO2peak) and maximal power output (Wmax). The VBM analyses revealed significant positive associations of VO2peak and Wmax with gray matter. Significant clusters with a cluster size of at least 30 voxels are pictured. Image credit: Wittfeld et al, doi: 10.1016/j.mayocp.2019.05.030.
“The most striking feature of the study is the measured effect of exercise on brain structures involved in cognition, rather than motor function,” said Mayo Clinic neurologist Professor Ronald Petersen, co-author of an editorial that accompanied the study.
“This provides indirect evidence that aerobic exercise can have a positive impact on cognitive function in addition to physical conditioning.”
“Another important feature of the study is that these results may apply to older adults, as well. There is good evidence for the value of exercise in midlife, but it is encouraging that there can be positive effects on the brain in later life as well.”
The finding of higher gray matter volume associated with cardiorespiratory exercise is in brain regions clinically relevant for cognitive changes in aging.
“This is another piece of the puzzle showing physical activity and physical fitness is protective against aging-related cognitive decline,” said Professor Michael Joyner, a Mayo Clinic anesthesiologist and physiologist and co-author of the editorial.
“There’s already good epidemiological evidence for this, as well as emerging data showing that physical activity and fitness are associated with improved brain blood vessel function. This paper is important because of the volumetric data showing an effect on brain structure.”
Long-term studies on the relationship between exercise and brain health are needed, which will be costly and logistically challenging to produce.
“Nevertheless, these data are encouraging. The findings regarding cardiorespiratory fitness and certain brain structures are unique,” said Dr. Clifford Jack Jr., a Mayo Clinic neuroradiologist and co-author of the editorial.
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Katharina Wittfeld et al. 2020. Cardiorespiratory Fitness and Gray Matter Volume in the Temporal, Frontal, and Cerebellar Regions in the General Population. Mayo Clinic Proceedings 95 (1): 44-56; doi: 10.1016/j.mayocp.2019.05.030
