So that's a good start. Is that all we have? I see some credible studies on pubmed (and plenty of studies with all the markers of being useless, some outright mentioning "CAM"-friendly goals in the abstract), but most of them involve things like mindfulness meditation as a method of improving performance on X, where X is some sort of motor-coordination task.

What the study you cited suggests interesting research could be done. My big question is that is any sort of hard focus activity of the same quality as meditation?