Many studies with both animals and people have found that exercise benefits cognition and brain function: improved spatial memory, working memory, and processing speed, to name a few. And that’s because the brain maintains a capacity to reshape and reorganize in response to physical and cognitive activity throughout our lives. That the environment can change the composition of the brain has prompted a lot of research into this so-called neuroplasticity. But there’s still a lot we don’t know.
Multiple teams of researchers explore the effects of physical activity on the brain in a series of studies published in the May issue of NeuroImage.
In one study, a team led by Henriette van Praag from the U.S. National Institutes of Health studied how brain networks are affected in rats after exercising on a silent spinner running wheel 11.5-centimeters (4.5 inches) in diameter. They focused on the hippocampus, an important brain area for spatial navigation and memory formation; it’s also an area that’s substantially modulated by physical activity. In humans, exercise increases hippocampal volume and vascularization, and many running-induced changes have been observed in the hippocampus of rodents as well.
Their findings revealed that running recruits input to new hippocampal neurons from brain areas that play a role in information processing. “For most people, physical health and brain health once seemed to have little connection,” van Praag told the Sunday Times. “This has been changed by discoveries in rodents that wheel-running increases production of new neurons in the hippocampus.”
In another paper, University of Oxford’s Claire Sexton and colleagues looked at magnetic resonance imaging (MRI) studies on how physical activity affects white matter in aging brains. Grey matter is where synapses occur, and white matter contains the axons, or nerve fibers, that connect different parts of the grey matter to each other. While higher levels of physical fitness have been shown to have beneficial effects on grey matter volumes in older adults, the relationship with white matter isn’t as well established.
In the 29 studies they reviewed, the team found that higher levels of physical fitness and activity were often linked with improved white matter outcomes and structure and reduced volume or severity of white matter lesions.
Around the world, age-related cognitive and brain decline is a growing health issue. Inactivity, both physical and cognitive, are major risk factors for decline in old age, and they can accelerate the signs of neurodegenerative diseases, like Alzheimer’s.