by Ross Pomeroy
Physical activity can do wonders for the body. Exercise can trim weight, chisel muscles, and strengthen the lower back, among many other benefits. Less overt, but no less consequential, physical activity can also buff up your brain. Science is increasingly revealing that the brains of those who regularly work out can look very different compared to the brains of people who don’t.
Changes can start to occur in adolescence. Reviewing the scientific literature in 2018, researchers from the University of Southern California found that for teens aged 15-18, regular exercisers tended to have larger hippocampal volumes as well as larger rostral middle frontal volumes compared to healthy matched control teenagers. The hippocampus is most commonly associated with memory and spatial navigation, while the rostral middle frontal gyrus has been linked to emotion regulation and working memory. Studies suggest that these structural changes translate to improved cognitive performance and better academic outcomes.
Exercise’s brain augmenting qualities extend into adulthood, even though the brain tends to be less ‘plastic’ (easily changed) as we get older. Rutgers University scientists beautifully demonstrated this in a study published early last year:
The researchers recruited older African Americans, all previously sedentary, to complete twenty weeks of twice-weekly cardio-dance exercise classes held at local churches and senior centers. As compared to the control group comprised of community members of similar age and background who did not exercise, those in the program showed significant improvements in dynamic brain connectivity (or “neural flexibility”) in their hippocampus and surrounding medial temporal lobe, as measured using resting-state functional MRI.
In another study, published in August 2019, scientists looked at 45 sets of adult identical twins, who, within their pair, all differed greatly in physical activity levels. “More active co-twins showed larger gray matter volumes in striatal, prefrontal, and hippocampal regions, and smaller gray matter volumes in the anterior cingulate area than less active co-twins,” the researchers found.
The scientists also probed the twins’ cognitive abilities.
“More physical activity may expedite preconscious processing of visual stimuli and, in somatosensory domain, improve selective attentional processing by dampening the strength of unattended deviant somatosensory signals,” they added.
The brain alterations do appear beneficial, but current twin studies are too small, and the participants too young, to find whether exercise-induced changes can actually reduce the risk of cognitive disorders or improve outcomes such as education or income.
Researchers have also tried exercise interventions on much older adults, even those with Alzheimer’s disease, to see if physical activity could repair their stricken brains. In 2016, a team of scientists recruited 68 older individuals with probable Alzheimer’s disease to determine whether moving more could help with their symptoms. Some subjects aerobically exercised for 150 minutes per week while others underwent a less rigorous control regimen of stretching and toning for 26 weeks. Compared to the control group, the aerobic exercise group improved more on the Disability Assessment for Dementia at the study’s conclusion. Boosts to cardiorespiratory fitness were also linked to improvements in memory and reduced atrophy of the hippocampus.
Working out also augments the brains of otherwise healthy older adults. Getting thirty minutes of physical activity each day does seem to preserve brain volumes in adults over age 70 compared to sedentary individuals, according to a study published in August of last year. Moreover, higher cardiorespiratory fitness was linked to lower levels of brain atrophy in the research.
One way exercise can induce changes in the brain is by increasing levels of the protein brain-derived neurotrophic factor (BDNF) in the blood, which is linked to neurogenesis. More BDNF may mean more new neurons in the brain. Regular exercise also increases the growth of additional blood vessels in the brain and helps maintain current ones, leading to boosted blood flow for the oxygen-hungry organ. Lastly, physical activity seems to keep microglia in good working order. Microglia “constantly check the brain for potential threats from microbes or dying or damaged cells and clear any damage they find,” Áine Kelly, a Professor in Physiology at Trinity College Dublin wrote for The Conversation.
Regularly moving one’s body may be the closest thing there is to a health panacea, for both outside the skull and inside.
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Ross Pomeroy is a contributor to RealClearScience.
