Staying fit could help keep your brain from shrinking and aging in your older years, suggests a new study out Friday. It found that middle-aged and elderly Americans who regularly even got an hour of light exercise during their weekly routine had larger brains on average than those who didn’t.
One common consequence of aging is a slow but steady decline in our brain’s size, with an average of 0.2 percent loss in volume associated with aging every year past 60, by some estimates. This shrinkage is so ubiquitous that scientists, including in this current study, use it as a proxy for measuring a person’s “brain age” and their risk of debilitating neurodegenerative ailments.
“We broadly assessed brain aging using MRI scans to determine the total brain volume in relation to an individual’s intracranial (skull) volume. In other words, there shouldn’t be very much extra space in the skull that is not filled by brain tissue,” lead author Nicole Spartano, an endocrinologist and research assistant professor of medicine at Boston University’s School of Medicine, told Gizmodo. “If we see lots of extra space, this suggests that the brain may have atrophied or shrunk. This brain atrophy is linked to dementia.”
Spartano is also co-director of the Physical Activity Station at the Framingham Heart Study, a decades-long project that began in 1948 and is still going (it was recently funded by the U.S. government for another six years). The study—which periodically tracks the health of residents living in Framingham, Massachusetts through a battery of tests—now even involves the children and grandchildren of the original volunteers. Spartano and her team looked at data from more than 2,300 volunteers from these later generations, with an average age of 53. Along with MRI scans, the team also had objective evidence of volunteers’ recent exercise habits, thanks to them wearing an activity tracker for up to a week at the time of their examination.
“We observed that people who are doing just a little bit more activity, even light-intensity activity, have larger brains than those doing very little,” Spartano said. For every hour of light exercise regularly done in a week, they specifically estimated, a person’s brain would avoid 1.1 years worth of shrinkage (or a loss of .22 percent in their volume).
“We want to be clear that this is a cross-sectional study using observational data, meaning that we can’t be certain that physical activity is causing people to have a better brain structure,” she added. “But studies like the Framingham Heart Study are important to continue funding because they help us discover associations that can be tested further with interventions and other study designs.”
The study was published Friday in JAMA Network Open.
Importantly, the link between more exercise and less brain shrinkage was seen even in people who got less than 150 minutes of moderate to vigorous exercise a week, which is considered the recommended threshold by public health organizations for getting the most benefits from exercise. And while people who walked more steps per day (at least 10,000) did have larger brains on average compared to those who only walked 5,000 or less, Spartano didn’t find a larger effect from higher-intensity exercise alone. In other words, people who got their exercise from walking in the park five days a week weren’t necessarily worse off, brain-size wise, than those who jogged or ran. That suggests, the authors say, that it doesn’t take much sweating at all to keep our brains in shape.
“I think this study could serve as great motivation for people who are unable (or feel unable) to perform the amount of physical activity recommended by guidelines,” Spartano said.
Indeed, public health organizations and even the federal government have started to openly plead that people do any amount of exercise, even if it’s less than what the guidelines suggest. And this isn’t the first study this year to show that every little bit of exercise counts when it comes to keeping us healthier. Finding a way to keep the aging brain safe is especially important, since we have currently no treatment or intervention that can clearly prevent or slow down the emergence of dementia. Some research has possibly, though not definitively, shown that exercise might be able to do that.
“I also want to emphasize that we know certain minority populations may have higher risks of developing dementia, so it will be critically important to devote more resources to exploring effective prevention measures in people of different race, ethnic, and socio-economic groups,” Sparnato said.
This current study wasn’t able to look at that angle, since most people in the Framingham Heart Study are white and of European descent, but Spartano and her team plan to study how exercise affects brain health among diverse groups in the near future.