Do Olympic athletes have strong brains as well as strong bodies?
But we still have a lot to learn about exactly how exercise changes the brain.
Recently, a team of scientists from the National Institutes of Health (NIH) conducted a series of experiments to try to tease apart the processes that are at work when we exercise.
To do this, they essentially tricked the muscle cells of mice into thinking they were doing aerobic exercise.
They did this by placing these muscle cells in petri dishes and treating them with a substance known as AMP-kinase.
The next step was to identify the chemicals that the cells released during this process, particularly the ones that could cross the blood-brain barrier.
Using mass spectrometry technology, the scientists honed in on cathepsin B, a protein that’s involved in helping sore muscles recover.
Finally, researchers added some of this protein to living brain cells in other petri dishes to see what would happen. When they did, they saw the cells begin to make proteins that are involved in the process of neurogenesis (the growth of brain cells).
Granted, it’s a stretch to make connections between the cells of mice in a petri dish with the activity of brains in humans, so the NIH scientists took their findings further.
They teamed up with researchers in Germany and created separate studies with rhesus monkeys and human participants.
In each case, they tested cathepsin B levels in the plasma of monkeys and humans, comparing an inactive control group with that of monkeys and humans who exercised on treadmills.
In both studies, cathepsin B levels showed an increase over time within the active group as compared with the sedentary control group.
In fact, researchers discovered that among human participants, the men and women whose fitness had increased the most also had the highest levels of cathepsin B in their blood.
Not only that, but the scientists added a cognitive component to the human study.
They found that in a figure drawing recall test, there was a positive correlation between pre- and post-test recall scores and cathepsin B levels.
Now these discoveries about the role of this protein represent just one small piece of the puzzle that could advance our understanding of how exercise benefits the brain.
In fact, scientists have also discovered that some of the connections between cathepsin B and health may be detrimental.
So more of this protein isn’t necessarily better. We still have a lot to learn about the role cathepsin B plays in brain health.
And because the participants in the human trial were all young men and women, I wonder if we might see differences in this study if it was repeated using participants that represented a wider range of ages.
Still, this study offers a ground-breaking glimpse into the complex processes that promote brain health.
If you’d like to check it out for yourself, you can find it in Cell Metabolism, volume 4, pages 1-9.
Now I’d like to hear from you. Do you recommend exercise to your patients? Please leave a comment below.