Maybe, just maybe 'ADHD' is an excuse to act like a heartless jerk.
Seems to me this is just an excuse. Do they ever change? Do they even want to? Nope. And I say that because my guy is nice to whom he chooses, when he chooses, then acts like a completely heartless jerk to others when the mood strikes.
It is crap. Immature, selfish crap. And no magic pill will make the huge difference. People only change if they want to.