En español l If you want to protect your brain against the effects of aging, a brisk daily walk may do more for you than brain teaser puzzles or social activities, a new study finds.

Brain Quiz: After age 20, thousands of brain cells die every day. True or False?

Walking may protect against an aging brain. — Dimitri Vervitsiotis/Getty Images

Researchers with the University of Edinburgh in Scotland, studying nearly 700 people in their early 70s, found that those who were most physically active had less brain shrinkage than those who got less exercise. At the same time, social and intellectually challenging activities, like going to the museum, learning a new language or visiting friends, seemed to have no protective effect on brain changes.

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"Those who took more exercise had less brain atrophy, less damage to the wiring of the brain, and greater volumes of grey matter, which are the 'thinking' cells. We did not find any associations between being more socially or intellectually engaged and brain health," says study author Alan Gow, a senior research fellow at the University of Edinburgh.

The research, published in the journal Neurology, is part of a long-term study on aging that involves a group of participants born in 1936. Those involved in this study were given brain MRI scans at age 73. They also filled out questionnaires about their physical activity, ranking it on a six-point scale from " moving only in connection with necessary (household) chores" to "keep fit/heavy exercise or competitive sport several times per week" and rated how often they participated in 15 different leisure activities.

While researchers wrote that exercise seemed to protect against brain shrinkage, they added that it's still unclear exactly how. Is exercise really protective, or is that those experiencing cognitive decline are less likely to exercise? While Gow stops short of recommending exactly how much exercise is best for brain health, Paul Thompson, professor of neurology at UCLA's School of Medicine, says any exercise increases the oxygen level of blood, and that may keep brain tissues healthier. "It's not necessary to run or even lift weights. Walking is just as effective. The bulk of the evidence is really just calories burned."

But don't throw out those brain teaser puzzles yet, says Thompson. They may still have a positive effect on the brain — just one that couldn't be measured by the type of scans the Scottish researchers used.

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