As the study points it out ("cross-sectional/longitudinal design") there may be a fundamental flaw in any conclusion one may draw from it: which part of any difference between observed populations is a "cause" (leading the subject to meditate), and which is an effect of it?

To illustrate the point let's say (as a maybe slightly contrived hypothesis) that meditation is interesting for you, or maybe even that you can only tolerate practicing it seriously, _iff_ (if and only if) your brain has the adequate structure, or is predisposed to evolve towards it.