A year of moderate exercise doesn’t just bulk up muscles — it beefs up the brain, too, a new study finds. A memory center in the brain called the hippocampus shrinks a little bit each year with age, but older adults who walked routinely for a year actually gained hippocampus volume, researchers report in a study to appear in the Proceedings of the National Academy of Sciences.
“I think it’s a very exciting contribution to see that walking at a fairly vigorous rate will actually affect a key structure of the brain,” says neuroscientist Carl Cotman of the University of California, Irvine, who was not involved in the study. “So for healthy elderly, it’s good news and would hopefully encourage people to figure that exercise is worth it.”
In the study, 60 adults aged 55 to 80 scaled up gradually until they walked for 40 minutes three times a week, enough to get their heart rates up. Sixty other participants did toning workouts that included weight training, yoga sessions and stretching for the same amount of time. After a year of toning, a part of these subjects’ brains called the anterior hippocampus lost a little over 1 percent of its volume. In contrast, a year of aerobic exercise led to about a 2 percent increase in anterior hippocampus volume.
Study participants who got their heart rates up performed slightly better on a memory test and had higher levels of a brain-aiding molecule called BDNF, the researchers found.
“You can think of this as not maintaining memory, but improving memory in this group — essentially turning back the clock and pushing these individuals back up their own personal trajectory by about two years,” says study coauthor Arthur Kramer of the University of Illinois at Urbana-Champaign. “Although it used to be thought that aging was a one-way street that was going the wrong direction, we know from our work and other work that that’s not the case.”
The place where the brain got bigger — the anterior hippocampus — is “an interesting place,” says Kramer, because that’s one of the few places where new nerve cells are born from adult stem cells throughout a person’s life. Researchers don’t yet know whether this cell replenishment is responsible for the volume increase, though.
Kramer and his colleagues are currently following the participants to see whether these brain benefits last, he says. Further studies are needed to figure out the duration and type of exercise that boosts brain power the most.
The new work underscores how a fit body includes a fit brain, Cotman says. “This whole idea that something as simple as exercise can actually benefit the brain and offset some of the changes that occur with normal aging is an emerging frontier — that’s what’s exciting about it.”
