That's fair. Meditation is hard, and I don't claim to be particularly good at it. On the other hand, I would say it's an extremely difficult task for just about anyone.
The study the article you posted cites successfully correlates brain differences with AD(H)D diagnosis. Part of the argument in the original article, though (which I can verify in my own case at least), is that while the brain affects observed behavior, behavior also affects the brain. So it's a very real possibility that experience and learned behavior are causing both the observed behavior and the brain chemistry differences.
The study the article you posted cites successfully correlates brain differences with AD(H)D diagnosis. Part of the argument in the original article, though (which I can verify in my own case at least), is that while the brain affects observed behavior, behavior also affects the brain. So it's a very real possibility that experience and learned behavior are causing both the observed behavior and the brain chemistry differences.