How Exercise Protects the Brain from Depression
Researchers at Sweden's Karolinska Institute published a neat study in the journal Cell last week that may shed some light on how and why exercise fights depression (press release here). It's fairly complicated stuff (to me, at least), and it's a mouse study – but I think it's interesting enough to be worth taking a closer look at.
It's fairly well established that exercise is an effective countermeasure to depression, but it's not clear why. Is it something to do with the cardiovascular system? Psychosocial factors related to getting out and exercising? Is there some chemical produced in the brain during exercise that fights depression (that would have been my guess), or a chemical produced in the muscles that then travels to the brain? Turns out it's none of the above.
Depression is very complex and multi-faceted, so there are likely lots of different factors involved. But the particular pathway identified in the new study is sort of the opposite of the chemical-produced-in-the-brain hypothesis. Instead, it appears that there's a chemical called kynurenine produced mainly in the liver in response to stress that then travels to the brain, where it's linked to (among other things) neuroinflammation, cell death, and depression. Exercise causes your muscles to increase levels of a protein called PGC-1alpha1, which in turn leads to higher levels of an enzyme that converts kynurenine into kynurenic acid – and the key difference is that kynurenic acid is unable to cross the blood-brain barrier, so (unlike kynurenine) it can't get into your brain and wreak havoc.
Read full article at below link
http://www.runnersworld.com/health/...n-from-depression?cid=socHE_20141002_32740996