Neuronarrative

Musings on the complicated business of thinking

Why Running is Incredible Medicine for your Brain

Get moving if you want to spark new brain cell growth

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I'm not much of a runner, but for years I've watched friends who run daily reap undeniable benefits--both physically and mentally. At the same time, research has been mounting that indicates exercise overall, and running in particular, is mighty good for your brain. A study from Cambridge University and the US National Institute of Aging adds to that argument, and this non-runner is finding it all very hard to ignore.

What makes running such a potent cerebral enhancer is its ability to spark neurogenesis: the growth of new brain cells. How it does this is still a mystery. It could be because exercise induces increased blood flow, or limits the production of stress hormones like cortisol, or some combination of reasons. However it happens, running could be a better antidepressant than anything you'll get from a pharmacist.

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Depression is linked to reduced neurogenesis, and it's possible that SSRI drugs like Prozac encourage the growth of new brain cells. Recent research on running indicates that it does the same thing, but on an even larger scale and without the infamous side-effects of the drugs, like weight gain and decreased sex drive.

The Cambridge study used mice to demonstrate how running beefs up the memory centers of the brain. Neuroscience researchers put one group of mice on a training regimen of running on a wheel up to 15 miles a day. The other group did nothing but nibble on carrots, wander around their cage and poop (the rodent corollary to a typical human office job).

Both groups were then periodically put in front of a computer screen showing two identical squares side-by-side. When the mice nudged the left square, they received a sugar pellet reward. When they nudged the right square, they received nothing. In other words, the mice had to remember which square yielded a reward.

The results: the running group scored nearly twice as high on the memory test as the sedentary group. To make it even more interesting, the researchers moved the squares closer and closer until they almost touched, making it harder for the mice to distinguish them. The sedentary mice got steadily worse as the squares got closer, but the running mice continued to figure it out. Researchers even tried to fool the mice by switching the squares in front of them. The running mice still nudged the square they'd been nudging to get the treat far more often than the sedentary mice.

The mice subsequently made the ultimate sacrifice for science. Brain tissue taken from the critters showed that the running mice had grown brand new grey matter during the experiment. Tissue from the dentate gyrus--a part of the hippocampus linked to new memory formation--showed an average of 6,000 new brain cells per every cubic millimeter, totalling hundreds of thousands of new cells. Not coincidentally, the dentate gyrus is one of the few areas of the adult human brain that can grow new brain cells.

What this and a growing list of research on the topic is telling us is that running and other forms of exercise can do things for the brain we're not even sure the best of modern pharmacology can do. I'm loathe to admit it, but the evidence is pushing me to the pavement. My hippocampus can use the boost.

Copyright 2010 David DiSalvo

David DiSalvo is a science and technology writer working at the intersection of cognition and culture.

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