I read this whole long thread. Fascinating. As far as I know I don't have ADHD, and I don't know too much about it.
But I was thinking that like every disorder there are the super mild cases aren't at all diagnosed because they are more of a personality than a problem. So I can say that I too am a sort of intense type of guy, for good and not so good, and I have felt many times how the lack of inner calmness feeds the addiction. I'm always looking at everything too big and complicated. Perhaps that is why I've grown so much from working on "one day at time", the idea is to put myself in a world where only the simple present is what exists. That's pretty focusing, right? Maybe the surrendering to Hashem also helps for this non-ADHD form of ADHD.
It could be I'm talking rubbish, tell me chevra what you think. Gut Shabbos.