How running and meditation changes the brains of the depressed

From NY Magazine
Spurred by New York Times article “Running as Therapy” by writer Jen A. Miller, the subject of exercise as mental health therapy is again in the news – but now with the added element of meditation. Miller’s memoir, Running: A Love Story, is coming out this week, and NY Magazine revisits Miller’s article and also considers new research on mental training:
… seeking professional help is crucial for those who struggle with mental-health issues.
But it is also true that for many people who are depressed, physical activity, and running in particular, helps tremendously. Now an intriguing line of research is suggesting that, for some, a combination of physical and mental training — called MAP training — may provide substantial help to those with major depressive disorder. Studies have already suggested that physical activity can play a powerful role in reducing depression; newer, separate research is showing that meditation does, too. Now some exercise scientists and neuroscientists believe there may be a uniquely powerful benefit in combining the two. In one study, published last week in the Nature journal Translational Psychiatry, a team led by Brandon Alderman at Rutgers University found that MAP training reduced depressive symptoms in a group of young people with major depressive disorder, and by an impressive margin — 40 percent on average, their data show.
The reason why this works is not yet clear. But Alderman and his colleagues have a hunch, taken from the neurogenesis theory of depression. Not long ago, scientists believed that by adulthood your brain had already produced all the neurons it ever would. Recent research, however, has shown that some regions, including the hippocampus, generate brand-new neurons throughout the lifespan. But in some — not all, but some — depressed people, the hippocampus generates fewer new neurons than in non-depressed people. This may be one of the reasons that antidepressants work: In addition to increasing serotonin production, the medications may also increase neurogenesis. (This, by the way, is one of the weirder facts of pharmaceutical research — many drugs work even though their inventors are not totally sure why they work.)