How walking can develop the brain

However, these earlier studies of brain plasticity have generally focused on gray matter, which contains the famous little gray cells, or neurons, that enable and create thoughts and memories. Less research has focused on white matter, the wiring of the brain. Made up mostly of nerve fibers enveloped in fat called axons, white matter connects neurons and is essential for healthy brain. But it can be fragile, thin and develop small lesions with age, decay that can be a precursor of cognitive decline. Disturbingly, it has also been viewed as relatively static, with little plasticity or the ability to adapt as our lives change.

But Agnieszka Burzynska, professor of neuroscience and human development at Colorado State University in Fort Collins, suspected the science was underestimating white matter. “It was like the ugly and neglected half-sister” of gray matter, she said, ignored and misjudged. She considered it likely that white matter possessed as much plasticity as its gray counterpart and could reshape itself, especially if people started to move.

So for the new study, which was published online in June in NeuroImage, she and her graduate student Andrea Mendez Colmenares and other colleagues set out to transform people’s white matter. They began by bringing together nearly 250 older men and women who were sedentary but otherwise healthy. In the lab, they tested the volunteers’ current aerobic capacity and cognitive skills and also measured their white matter health and function, using a sophisticated form of brain MRI.

Then, they divided the volunteers into groups, one of which began a supervised stretching and balance training program three times a week, to serve as active control. Another started to walk together three times a week, quickly, for about 40 minutes. And the last group started dancing, meeting three times a week to learn and practice line dances and group choreography. All groups trained for six months, then returned to the lab to repeat the tests from the start of the study.

And, for many, their bodies and brains had changed, the scientists found. The walkers and dancers were in better aerobic shape, as expected. More importantly, their white matter seemed renewed. In the new scans, nerve fibers in parts of their brains looked larger and all of the tissue damage had shrunk. These desirable alterations were more common in walkers, who have also performed better on memory tests now. Dancers, in general, no.