Exercise and "Miracle-Gro for the Brain"*

HOW EXERCISE MAY HELP THE BRAIN GROW STRONGER!
An article by Gretchen Reynolds for the New York Times attempts to more simply explain new research findings in mice that may help scientists understand how exercise benefits the brain of humans.
 
She reports that regular exercise is known to increase levels of Brain-Derived Neuotrophic Factor (BDNF) in our blood as well as in brain tissue. BDNF is a protein that encourages brain cell (neuron) growth and strengthens connections (synapses) between cells that allow better functioning. “Low levels of B.D.N.F. have been associated with cognitive decline in both people and animals.”
 
In this mouse study, healthy animals that were allowed to use exercise wheels for a month did so (mice like to run), and those who were NOT given wheels could only remain sedentary. At the study’s end, the brain tissue of wheel-running mice had much higher levels of BDNF than sedentary mice. Through sophisticated methods, it was shown that the gene responsible for turning on the production of BDNF was significantly blocked by the binding of inhibitory molecules in the sendentary mice but less so in the running mice, allowing the gene to prompt production of increased BDNF in the exercisers’ brains.
 
[NOTE: This kind of inhibition is known in the scientific world as one type of “epigenetic” change, which explains how gene function can be altered by external factors like lifestyle and the environment, and thus influence whether we are healthy or develop certain diseases.  The term “epigenetics” refers to changes in gene expression that occur not as a result of modifications in the actual code (DNA sequence) we are born with, but due to silencing or activation of that code by outside forces. The inhibitory molecules (called histones) that were found to inhibit the BDNF genes in the study mice are known to cause epigenetic changes.]
 
In addition, levels of a substance (a ketone) were higher in the exercisers. The ketone appeared to decrease binding of the inhibitory histones to the BDNF genes. The effect of the higher brain ketone levels was to keep the BDNF genes of exercising mice free of inhibition, and thus more BDNF was produced in their tissue.
 
Ketones are by-products of fat breakdown, and are created by the body during strenuous endurance exercise, when stored sugar is depleted, blood sugar levels start to fall, and it must rely partly on fat for fuel. The tiny ketones are able to cross the blood- brain barrier.  Reynolds article explains the study in detail and provides quotes from the researchers and other experts.
 
 
The ending sentence in the research study concludes “these new findings reveal with molecular detail one way in which exercise can affect the expression of proteins in the brain. This new understanding may provide ideas for new therapies to treat psychiatric diseases, such as depression, and neurodegenerative disorders, such as Alzheimer’s disease.”
 
As runners, we can be motivated by these findings to stay committed to regular exercise.  We hope science will help us understand the specifics of how running benefits our brains such that we can train appropriately, and that medications will be developed that prevent and treat disease.
 
RUN HAPPY!
 
http://well.blogs.nytimes.com/2016/06/15/how-exercise-may-help-the-brain-grow-stronger/?_r=0
 
https://en.wikipedia.org/wiki/Epigenetics
 
https://elifesciences.org/content/5/e15092

* "NYT: A version of this article appears in print on 06/21/2016, on page D6 of the NewYork edition with the headline: u2018Miracle-Grou2019 for the Brain."