Yet another study has found that being a lazy-bones now might leave you lacking in the brain department later.
Researched published in the February 2016 online issue of Neurology suggests that not being physically active in middle age is associated with having a smaller brain 20 years down the road.
Nearly 1,600 adults with an average age of 40 volunteered to undergo a brain MRI and take a treadmill test at the start of the study, and then repeat the whole process two decades later.
The researchers measured participants' fitness levels based on how long they were able to work out on the treadmill before their heart rates reached a certain level. They found that the participants who performed poorly and had exaggerated blood pressure and heart rate responses while on the treadmill (read: people who are out of shape) at the start of the study were more likely to show reduced brain volume 20 years later.
While it's normal for your brain to shrink some with age, this study suggests that the less active a person is in middle age, the faster the brain shrinks as they enter the senior years.
"We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain aging," said study author Nicole Spartano, PhD, with Boston University School of Medicine, in a press release.
These conclusions are similar to a December 2015 study published in JAMA Psychiatry: More than 3,000 adults between the ages of 18 and 30 were asked to fill out questionnaires regarding their TV and exercise habits sporadically over the course of 25 years, as well as complete several tests to measure their cognitive function.
Those who landed in the high TV-viewing category (about 11 percent) or low exercise category (16 percent) were more likely to receive a poor score on cognitive performance on at least one of the tests. And those who fell into both groups (3 percent) doubled their odds of poor cognitive performance — specifically slower processing speed and worse executive function.
Why Too Much TV and Not Enough Exercise Can Shrink and Weaken Your Brain
The link between physical activity and cognitive health is nothing new, says Gary W. Small, MD, professor of psychiatry and biobehavioral sciences and Parlow-Solomon professor on aging at the David Geffen School of Medicine at UCLA and co-author of 2 Weeks To a Younger Brain. "We know that people who walk briskly — or do any kind of aerobic exercise — increase circulation to the brain so that oxygen nutrients are feeding those brain cells," he explains.
Dr. Small adds that working out also boosts the amount of BDNF (brain-derived neurotrophic factor), which stimulates brain cells to sprout branches and communicate more effectively.
"Other studies in older people find that those who exercise show an increase in size of the hippocampus, which is an important memory center underneath the temples of the brain," he says. "And in addition to aerobic exercise, other studies are showing that building brawn builds your brain, as well."
While scientists have yet to discover why pumping iron can pump up your brain function, he speculates that it may have something to do with "releasing chemicals and other factors."
And when it comes to avid TV viewing, Small says there are a couple of reasons why your brain may bottom out: First, there's the fact that people tend to be less active when watching Bravo, Hulu or Netflix hour after hour.
"Then there's a study… which found that 10 minutes of stimulating conversation is better for your cognitive health than 10 minutes of television," he says. "So the idea there is that the average television show is a very passive experience without much mental stimulation."
So is it too late for people who were inactive TV-lovers back in the day — or yesterday — to turn their health around?
"I always say it's never too early and never too late," Small says. "It's never too early because the sooner you get started living better habits, the easier it will be to maintain them. And we've seen a lot of positive effects from older people getting involved in a healthier lifestyle later in life, so people should not be discouraged."