Study: Physical activity predicts gray matter volume in brain
Physical activity is associated with larger volumes of gray matter tissue in the brain, which, in turn, is associated with lower risks of developing dementia or cognitive impairment in old age, a study published in the latest issue of Neurology found.
Volume of gray matter (GM) tissue in the frontal, temporal and occipital lobes of the brain decreases with old age, which is believed to precede and lead to mild cognitive impairment (MCI) and dementia in geriatric patients. The researchers conducted a longitudinal study to examine whether physical activity was associated with less of a decrease in GM and cognitive impairment.
The study included 299 patients aged 65 years or older from the Cardiovascular Health Study Cognition Study. The average levels of physical actitvity for all subjects were measured between 1989 and 1990, all of which were standardized to number of blocks walked per week. Two to three years later, all participants underwent low-resolution MRIs; only the 299 cognitively-normal participants were followed for the entire study. Nine years after the benchmark physical activity measurements, participants underwent high-resolution MRIs, and thirteen years later participants were evaluated for MCI.
One hundred sixteen of the 299 participants were diagnosed with either mild cognitive impairment or dementia, which roughly mirrors the conditions’ incidences in the general population. The authors found that walking 72 or more blocks per week (approximately six to nine miles) was associated with significantly higher volumes of gray matter tissue, which correlated to significantly lower risks of cognitive impairment.
Participants who walked 72 or more blocks, representing the upper quartile of physically active participants (median physical activity was 56 blocks), presented significantly higher gray matter volumes in the frontal, temporal and occipital lobes as well as in the entorhinal cortex and hippocampus. Moreover, no regions showed greater gray matter volumes with less physical activity.
“The results of this study establish three critical findings,” Kirk I. Erickson, PhD, of the department of psychology at the University of Pittsburgh, and co-authors wrote. “First, greater amounts of physical activity are predictive of greater GM volume nine years later. Second, walking relatively long distances … was necessary to detect differences in GM nine years after the baseline evaluation of physical activity. Third, greater GM in the inferior frontal gyrus, the hippocampus and the supplementary motor area was associated with a reduced risk of developing cognitive impairment.”
The authors cautioned that they could not establish that physical activity causes a preservation of higher GM volumes because of the possibility that poor health led to both less walking and reduced GM volumes. In addition, Erickson and colleagues acknowledged that self-reported physical activity levels represented a weakness that should be carefully considered in future studies aiming to determine physical activity thresholds associated with lower risks of cognitive impairment.
“In short,” the authors concluded, “walking greater distances was associated with greater GM volume in specific regions, and greater GM volume was associated with a lower risk of experiencing cognitive impairment in later years.”
Volume of gray matter (GM) tissue in the frontal, temporal and occipital lobes of the brain decreases with old age, which is believed to precede and lead to mild cognitive impairment (MCI) and dementia in geriatric patients. The researchers conducted a longitudinal study to examine whether physical activity was associated with less of a decrease in GM and cognitive impairment.
The study included 299 patients aged 65 years or older from the Cardiovascular Health Study Cognition Study. The average levels of physical actitvity for all subjects were measured between 1989 and 1990, all of which were standardized to number of blocks walked per week. Two to three years later, all participants underwent low-resolution MRIs; only the 299 cognitively-normal participants were followed for the entire study. Nine years after the benchmark physical activity measurements, participants underwent high-resolution MRIs, and thirteen years later participants were evaluated for MCI.
One hundred sixteen of the 299 participants were diagnosed with either mild cognitive impairment or dementia, which roughly mirrors the conditions’ incidences in the general population. The authors found that walking 72 or more blocks per week (approximately six to nine miles) was associated with significantly higher volumes of gray matter tissue, which correlated to significantly lower risks of cognitive impairment.
Participants who walked 72 or more blocks, representing the upper quartile of physically active participants (median physical activity was 56 blocks), presented significantly higher gray matter volumes in the frontal, temporal and occipital lobes as well as in the entorhinal cortex and hippocampus. Moreover, no regions showed greater gray matter volumes with less physical activity.
“The results of this study establish three critical findings,” Kirk I. Erickson, PhD, of the department of psychology at the University of Pittsburgh, and co-authors wrote. “First, greater amounts of physical activity are predictive of greater GM volume nine years later. Second, walking relatively long distances … was necessary to detect differences in GM nine years after the baseline evaluation of physical activity. Third, greater GM in the inferior frontal gyrus, the hippocampus and the supplementary motor area was associated with a reduced risk of developing cognitive impairment.”
The authors cautioned that they could not establish that physical activity causes a preservation of higher GM volumes because of the possibility that poor health led to both less walking and reduced GM volumes. In addition, Erickson and colleagues acknowledged that self-reported physical activity levels represented a weakness that should be carefully considered in future studies aiming to determine physical activity thresholds associated with lower risks of cognitive impairment.
“In short,” the authors concluded, “walking greater distances was associated with greater GM volume in specific regions, and greater GM volume was associated with a lower risk of experiencing cognitive impairment in later years.”