Meditation has long been used to induce calm and physical relaxation. But research on its potential uses for treating medical problems “is still in its very early stages,” and designing trials can be challenging, said Richard J. Davidson, a neuroscientist who founded the Center for Investigating Healthy Minds at the Waisman Center, at the University of Wisconsin-Madison. “So it’s not surprising the scientific literature is filled with mixed findings at this point in time.” Some…