Then the researchers crosschecked all of this data and soon noted several interesting and consistent patterns. Perhaps least surprising, those men and women harboring a high genetic risk for depression were more likely, in general, to develop depression than volunteers with low risk scores.
At the same time, physically active people had less risk than people who rarely moved, and the type of exercise barely mattered. If someone spent at least three hours a week participating in any activity, whether it was vigorous, such as running, or gentler, like yoga or walking, he or she was less likely to become depressed than sedentary volunteers, and the risk fell another 17 percent with each additional 30 minutes or so of daily activity.
This link between movement and improved mental health held true for people who had experienced depression in the past. If they reported exercising now, their risk for a subsequent episode of depression fell, compared to the risks for inactive people with a history of depression.
Exercise also substantially altered the risk calculus for people whose DNA predisposed them to depression. If they carried multiple worrisome gene snippets but often exercised, they were no more likely to develop depression than inactive people with little genetic risk.
In effect, physical activity “neutralized” much of the added risk for people born with a propensity for depression, says Karmel Choi, a clinical and research fellow at Massachusetts General Hospital and…