Walking May Preserve Brain Size And Memory In Later Life
So strictly speaking, they have not assessed whether walking helped to preserve each
person's brain volume, only that people who walked the most tended to have larger grey matter volumes than those who walked less.
There is no proof of cause and effect here (this was a longitudinal study and not a controlled trial), only the suggestion of a strong link, and the reasonable, but still arguable, assumption that it is walking that preserved brain volume rather than having more brain volume encouraged people to do more walking.
The reasonableness of assuming it is the former is bolstered by the numerous studies that show our brains shrink as we age.
Walking May Preserve Brain Size And Memory In Later Life