In 2020, the world spent more than $7 billion on supplements that promised to enhance brain health. We may as well be setting that money on fire. The quest for the perfect IQ-boosting pill, memory game, or creativity elixir has not been a successful one.
If you’re seeking that one weird trick to improve your brain health, the best place to look might be your feet. That’s the conclusion I reached after my journey through hundreds of studies assessing brain zapping, microdosing, games, and other popular interventions for my book, The Tailored Brain. It turns out one of the only legitimate ways to tailor our brains has been available to us all along: physical activity.
Getting moving has a number of effects that tie directly to the brain’s resilience, from increased blood flow to refreshed connections in the brain itself. But one of the less appreciated ways to enhance these effects even further is to engage with other brains while we engage in exercise.
Humans are, like elephants or naked mole rats, a social species. Evolution shaped us not as single brains making our way through life but as brain collectives, interacting, problem-solving, creating, and, yes, moving through the world, literally, together. A fascinating new hypothesis from evolutionary biology posits that physical activity builds a buffer against the insults of age so that we stick around and are healthy enough to support other people, not so we can sit alone in a cave or a castle and be lonely geniuses.
Interacting with others as we move can unburden our minds, leaving space for crisp new ideas, increased attention, memory power, and a lighter mood. The best news is that even modest amounts of activity offer benefits. Science says so.
How physical activity and social interaction work together
If you find yourself groaning at the idea of more exercise, that may be because “exercise” is an artificial form of physical activity, which can encompass many pursuits from gardening to shopping. And it may be that doing something social while we move around comes to us naturally.
Harvard evolutionary biologist Daniel Lieberman co-authored a recent review of evidence for the argument that physical activity is an evolutionary adaptation that supports brain health into old age. The idea is that as humans evolved, we moved around a lot to keep ourselves fed and cared for, which supported brain health. Both the physical activity and the healthy brain in turn made us able to care for younger generations into old age.
This idea is an evolutionary explanation for why humans survive well past the reproductive years, which is extremely rare among animals. It goes hand in hand with the “grandmother hypothesis,” which posits that in our post-reproductive years, we stick around to care for little ones in younger generations who carry our genes. By keeping them alive, we keep alive the genes we passed along to them, too. Lieberman and co-authors add to this picture by proposing that physical activity supports the brain and body “healthspan” that allows for a physically active old age.
Exercise gets molecules moving, too, for repairs and remodeling
Physical activity causes damage, Lieberman and his co-authors say, in the form of muscle breakdown and release of damaging oxidant molecules. But the scientists offer evidence that when we repair this damage, we overshoot a bit, leaving things even better off than when we started. A huge antioxidant release in response to oxidants from exercise, for example, could buffer against inflammation, which is linked to degenerative brain diseases.
Even a little exercise, like 20 to 30 minutes a few days a week, goes a long way. Moving around gets our blood moving, and that moves molecules to our brains more efficiently. It’s well known that physical activity can send more oxygen to the energy-hogging brain, for example. The presence of oxygen triggers cells to start using glucose, the brain’s preferred energy molecule.
Low glucose use in the brain has been linked to Alzheimer’s disease, even in people without symptoms who carry genetic risk variants for the condition. One 2017 study looked at how well the brains of 93 late-middle-aged adults metabolized glucose after physical activity. The researchers used devices to objectively track physical activity for a week and found a link between moderate physical activity and enhanced glucose use in the brain, which is an indicator of good brain health.
Another study using devices for objective physical activity measurement found that people with higher levels of daily physical activity and good motor abilities scored better on tests of cognition. The 454 participants in that 2019 study underwent the monitoring and testing in the years before their deaths, and agreed to donate their brains for analysis after their deaths. Even when the brains showed changes linked to conditions such as Alzheimer’s disease, physical activity levels and motor ability each separately were associated with better performance on the cognitive tests. The researchers speculated that factors like physical activity could enhance the brain’s “cognitive reserve,” or ability to work around damage to the brain and maintain function.
Another measure of the brain’s flexibility and health is how easily it switches from one task to another, which is called “set shifting.” Set shifting is different from multitasking, which is when you’re doing two things at once, like talking on the phone and making dinner. We use set shifting in social situations, for example: think of how you redirect mental resources at a party as you shift from talking with someone about the food to a conversation with someone else about the state of the nation. In a 2021 meta-analysis of 22 trials of how easily people engaged in set shifting, the authors found that light physical activity was associated with easier set shifting, especially for people who were older.
This ability to adapt fluidly as a situation shifts is the domain of the CEO in our heads, otherwise known as our executive function. Executive function is our ability to manage ourselves through working memory, self-control, and flexibility in thinking. A meta-analysis published in 2020 assessed the findings of 36 randomized controlled trials of physical activity’s effects on brain-related measures of executive function. Trials like these are considered the most rigorous kind of research design. These 36 studies collectively included 4,577 young people, and the review pointed to links between physical activity and benefits for different aspects of executive function.
A similar kind of review, also published in 2020, looked at the results of 33 randomized trials that had included people over age 55 and also found a benefit of physical activity for executive function. Yet another analysis of 25 randomized trials found physical exercise-related improvements in several features of executive function in healthy adults age 60 and older.
These analyses of findings from more than 100 studies suggest that physical activity benefits the aging CEO in our brains. If Lieberman and his colleagues are right, one upshot may be a longer healthspan for our brains to match our life spans.
How supplements have turned out to be “brain enhancer” duds
The pursuit of the fountain of youth has never turned up a supplement that works as well as physical activity.
Researchers initially thought omega-3 fatty acids might get some traction as brain improvers, especially for mood. These fatty acids stood out in uncontrolled studies, where scientists just observe people who have been exposed to a factor and compare them with those who haven’t. These so-called observational studies hinted enough at brain benefit from these fatty acids that omega-3s became quite popular as an “evidence-based” brain supplement. Imaging also seemed to indicate that brain connections might reconfigure in presumably beneficial ways with omega-3 use.
We use these molecules in building our brains, so the defensible intuition was that we could take them in pill form and reap brain benefits. But when omega-3 supplements were entered into more rigorous randomized controlled trials, they didn’t keep their brain-based promises for effects on mood and anxiety. They didn’t even best corn oil for improving depression symptoms when added to an antidepressant therapy. And randomized studies of the effects of these fatty acids on cognitive impairment, along with mood, have found no benefit.
Generally speaking, no supplement stands out for brain benefits. Longtime stalwarts in some circles, including ginkgo biloba and vitamins B, D, and E, haven’t yielded protection from cognitive impairment in studies. So until we can get the effects of exercise into pills, the best we can do for cognitive enhancement is regular physical activity … perhaps with a dose of engagement with other brains.
The benefits of exercise and social interaction are a two-way street
When I talk about “being social,” the definition is broad and largely references connections between brains, in person or from far away in time or space. You and I are making a connection right now. Hello!
What I found in writing The Tailored Brain is an interesting interaction among a few easily accessible tools that seem to best serve our brains. You’ve met one: physical activity. Another is making connections with other people. When we connect with other people and hear their stories, we can boost general thinking capacity and enhance the influence of being physically active. Both can ease stress and anxiety, sand the edges off a bad mood, and lighten cognitive loads.
Strong social links on their own offer life span benefits that could be on par with quitting smoking. A 2020 study in China of almost 8,000 people age 45 or older found that social behaviors, including engaging in sports, benefit cognitive skills. The authors also concluded that the window of opportunity to take up these practices and gain improvements stays open into old age.
The benefits of exercise and social interaction are a two-way street. Physical activity eases anxiety, stress, and an overloaded brain, which makes space for us to truly engage socially. It’s tough to have empathy when your brain is sitting there like the “this is fine” meme featuring the dog in the room on fire. There’s no space left to react to, or try to interact with, or understand others.
But if we move around with others, as generations of humans have before us, we make that space. And if we share our burdens with each other on an evening walk, we get brain-boosting exercise and brain ease all at once, perhaps in a way that feels less forced and more like a fit for the brains that nature gave us.
Emily Willingham is a science journalist and author of The Tailored Brain: From Ketamine, to Keto, to Companionship, A User’s Guide to Feeling Better and Thinking Smarter (Basic Books, 2021) and Phallacy: Life Lessons from the Animal Penis (Avery, 2020). She is a regular contributor to Scientific American.