The only part of this that rhymed with something I'm aware of is growth in the PFC in practicing meditators and a relation to improvement of ADHD symptoms among other things, though I don't recall whether it was a good study or not. I think I read that more than a decade ago.

That's changes in brain chemistry via lifestyle changes.

Meditation, if practiced at least adequately intense, creates a time interval that is entirely different to anything an ADHD mind is accustomed to. Meditation is not a dream, not the Default Mode Network under control. You are awake, "lucid", not rooted in your imagination or some other cognitive style/process resulting from "hyperlight association" or similar common phenomena.