Exercise—even something as simple as walking—has long been known to fight depression. Now Swedish researchers think they know why (and it has nothing to do with the feel-good endorphins you hear about all the time).
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They made the discovery by studying genetically modified mice that are resistant to stress. So what's stressful in the rodent world? Loud noises and flashing lights, according to a report in the Washington Post. And just as stressed out people can be prone to depression, normal mice exposed to noise and lights can get depressed, losing interest in food and becoming lethargic.
By studying mice that were immune to this stress-triggered depression, the researchers from the Karolinska Institute in Stockholm found that a protein called PGC-1alpha1 might be key. Made by active muscles, PGC-1alpha1 seems to help prevent a stress-related protein, known askynurenine, from crossing into the brain and causing depression, according to the study published in the journal Cell. The stress-resistant mice are apparently awash in PGC-1alpha1, which helps make them better able to handle the equivalent of a high-pressure job.
Although discovered in mice, the scientists also found PGC-1alpha1 is abundant in humans. They tested muscle biopsies of adult volunteers before and after three weeks of endurance training, and found the participants had much higher levels of the protein than when the study began, according to the New York Times.
"This study opens therapeutic avenues for the treatment of depression," the authors concluded. In other words, it might be possible to find treatments that stimulate the protein in the muscles or blood rather than affecting the brain (like antidepressants do).
While new treatments are clearly a long way off (and more research is needed to confirm the findings), we now have a better understanding of how exercise might help prevent and treat depression. Most adults should do strength training twice a week plus 150 minutes of moderate physical activity or 75 minutes of more vigorous activity, according to the Centers for Disease Control and Prevention.
If don't already, get yourself in the habit of exercising now to keep your mind and body going strong.
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