Now Reading: Walking not only rearranges your neurochemistry (I knew it), it grows your brain

In a world where functional MRI (fMRI) is mostly being used to figure out how people can eat more potato chips (See post: What we are up against in motivating health: Cognitive Science, Sex and advertising | The Economist | Ted Eytan, MD), I am excited to see a use of the technology that we can all embrace.

I am currently reading the excellent report from the Bipartisan Policy Center ( @BPC_bipartisan ) that just came out: Lots to Lose: How America’s Health and Obesity Crisis Threatens Our Economic Future. Washington, DC; 2012 (and will post on it later), and was immediately taken by the image on the right. It’s used to illustrate the part of the report that provides supports for changing exercise culture in schools.

I have been tweeting and talking about how I never forget a walking meeting and there’s something about the neurochemical effects that make them extra special. So I decided to follow up on this data. I didn’t find the specific reference mentioned in the image, but I found ones that are very close. And the findings are kind of remarkable. I’m not a neurophysiologist, but my excessive schooling does allow me to figure out most things written about the human body, so I dove in.

In Hillman CH, Erickson KI, Kramer AF. Be smart, exercise your heart: exercise effects on brain and cognition. Nature Reviews. Neuroscience. 2008;9(1):58-65, the authors look at the data, across the life spectrum, around cognitive function and exercise. They note that there is surprisingly little research, especially in young adults. They think this is when cognition peaks (what, it goes downhill?) then and so there’s less of an interest in the impact of exercise relative to older people. And here’s what they found:

Physical activity training appears to have both broad and specific cognitive effects: broad in the sense that various different cognitive processes benefit from exercise participation, and specific in the sense that the effects on some cognitive processes, especially executive control processes (which include scheduling, planning, working memory, multi-tasking and dealing with ambiguity), are disproportionately larger.

In other words, the part of your brain that deals with the highest level functions is better at managing itself (and you) among people who exercise. They further look at “top down control” and “behavioral control” which have greater brain activity among people who exercise. These functions allow the brain to deal with unexpected things int he environment and not-overreact.

People who are sedentary have brains that fire more in the overreaction area, and less in the control and manage area, in other words, they are less capable of maintaining steady state in the face of challenges.

Then there’s the hippocampus, where the memory lives. In animal Exercise causes the brain to grow (yes, grow, as in new cells) throughout life.  The babies of mothers who exercise also have more cells in this part of the brain at birth ( shoutout to you, Alan Greene, MD ).

How does this happen? They don’t know for sure but they think it’s because of…. neurochemistry. Blood levels of brain proteins (BDNF) increase after exercise treatment, as does generation of blood vessels and actual neural cells. There’s a twist – in animals that are “socially isolated,” the good effects of the neurochemistry are delayed an stunted. 

Get it? Exercise + being social  (AKA “the walking meeting”) = better brain functioning, actual brain growth, better management of one’s self and the environment. 

In Davis CL, Tomporowski PD, McDowell JE, et al. Exercise improves executive function and achievement and alters brain activation in overweight children: a randomized, controlled trial. Health psychology : official journal of the Division of Health Psychology, American Psychological Association. 2011;30(1):91-8., the researchers randomized sedentary, overweight, children aged 7-11 to no exercise, exercise 20 minutes every day, or 40 minutes every day and looked at their brain function AND pulled out the fMRI machine to look at how their brains worked real time.

And…they found the same thing, the brains of the children actually work differently after 3 months, and those with 40 minutes a day showed a greater change than the 20 minutes a day kids. 

Although the fMRI images in the article don’t exactly correlate to the ones here, they show the same pattern of better “Executive Function” – increased activity in the front part of the brain (bilateral prefrontal cortex) and decreased activity in the back of the brain (bilateral posterior parietal cortex). These are brains that are able to 

regulate one’s behavior (e.g., inhibiting inappropriate responses, delaying gratification) [which is important] is important for a child to succeed in elementary school (Blair, 2002; Eigsti et al., 2006). This effect may have important implications for child development and educational policy.

Oh, and they also scored better on math testing.

These authors’ best guess of how this happens is the same as the ones above, it’s from neurochemistry, stimulated by movement, not as as side effect of better heart health:

Thus, rather than being mediated by cardiovascular benefits, the cognitive changes due to exercise may be a direct result of neural stimulation by movement.

There has been some talk lately about whether exercise is beneficial for 100% of the population, and the problem with that discussion is that it focuses on a very narrow set of biological markers (blood pressure and blood lipids).

This ignores a vast array of other benefits that extend beyond the heart to the mind, body, and the soul. Not to mention family, community, society. In other words, exercise may not bring a person to 100% health; it brings them closer to Total Health. Check it out, schedule a walking meeting today :).


Super post Ted!  I love the picture!  My eldest son Freddie has to run back and fourth every night while he “imagines.”  I am so glad there is scientific support for this activity. He know he needs to do this but it it tends to frustrate the folks he think he should just be able to sit still.  
Speaking of sitting still, just couldn’t do it in the traditional cancer round table focusing on HIT on Thursday.  Several of us got up and stood in the back of the room.
Thought of you fondly 🙂

 @ReginaHolliday I STILL frustrate people who think I should be able to sit still. Freddie can look forward to a lifetime of educating people about the power of movement :).
We’ll have to have a short code so that we can text each other from wherever we are to ask for permission to stir things up. Fortunately the answer will always be “do it.” It really does take a doctor and a patient!

“exercise may not bring a person to 100% health; it brings them closer to Total Health”
I’m an avid walker, but admit I sometimes get discouraged because I never seem to loose weight. Then I remind myself that I’m working towards Total Health not a dress size and just because someone is skinny doesnt mean they can walk 6 miles without huffing and puffing. Walking is also where most of my blog ideas come from. My brain just seems to be free from the chaos and good things flow freely. Great post Ted.

Ted Eytan, MD