The World Health Organization calls it their “important factsAs for physical activity, he states that it “enhances thinking, learning and decision making.” The link between exercise and brain health is a credo among health researchers and policy makers, not to mention among health journalists like myself.
So two studies published last month were whiplash-inducing. First, a major critical review suggesting that firm evidence for a brain-activating effect of exercise is thin or non-existent. Then, a few days later, his large-scale study of over 250,000 subjects using cutting-edge new technology confirmed that the effects were indeed real. I’m standing here because the dust is still settling.
For years, observational studies have pointed to the benefits of exercise for preventing cognitive decline. Check to see if the ability is the most degraded. one meta-analysis Even low to moderate exercise levels were found to reduce the risk of subsequent cognitive impairment by 35%. Another study concluded that 1 of his 7 cases of Alzheimer’s disease could be prevented by meeting the recommended minimum of 150 minutes of exercise per week.
The problem is that these observational studies cannot prove causation. Maybe exercise helps the brain. Or maybe there are other factors that affect both mind and body. Perhaps people who eat more vegetables tend to exercise more. and For example, have a healthy brain.
A better option for establishing causality is interventional studies. Assign some people to exercise a lot, have other people sit on the couch and see whose brain works best. There are not many, and they tend to last only a few months or years at most, limiting the conclusions that can be drawn.
new critical review, Published in Nature Human Behavior A team of Spanish researchers led by Luis Ciria of the University of Grenada focused exclusively on these more rigorous intervention studies. We adjusted the results to account for factors such as publication bias that tended researchers not to publish negative results.
The results were overwhelming. While the majority of individual trials found positive effects, the pooled and adjusted results found only ‘negligible’ evidence of cognitive benefit.
“Importantly, our study does not rule out the existence of these effects,” Ciria noted in an email. We’re just concluding.” Still, he suggested that organizations like the WHO should refrain from citing brain health as a reason for exercise until better evidence is available.
It was against this background that a group of Canadian, Swiss and US researchers, including Matthieu Boisgontier from the University of Ottawa, published their own paper. in Scientific Reports A few days later.
Boisgontier explains: “We say ‘not so fast’ because there is additional causal evidence suggesting that both moderate and vigorous physical activity have lifelong cognitive benefits.”
Boisgontier’s paper uses a technique called Mendelian randomization to combine the strengths of observational studies (large numbers of participants, long timeframes) with those of interventional studies (randomized to a greater or lesser degree of exercise). I’m here.
Randomization is effectively done at birth. Some people are born with certain genetic variants that make them more likely to exercise throughout their lives. Because the effects of these gene variants on cognitive function are unknown, we suggest that higher levels of exercise made a difference when people with these variants scored better on cognitive tests. increase.
Sure enough, that’s what the results showed. In his database of 257,000 people who underwent genetic and cognitive testing, previous researchThose who had the gene variant associated with higher exercise levels scored better on cognitive tests. Interestingly, the benefits of moderate exercise are about 50% stronger than those of vigorous exercise, suggesting that you don’t need to be extremely tired to see the benefits.
Boisgontier concedes that this one study doesn’t quite solve the problem. But this is an important step to strengthen the WHO’s claims, which Ciria agrees. “These are the kinds of studies we need to reveal the real effects of exercise on cognitive function,” he said of his new findings.
In the meantime, Ciria points out, this controversy should not deter anyone from a movement whose physical and social interests are firmly established. Let’s not forget the joy of doing something.The value of exercise may simply lie in its fun nature.”
Alex Hutchinson is the author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. follow him on twitter @ sweat science.
