Give the same substance to someone already at a normal level and he will become overexcited.
Just like putting weights on a scale can balance an unbalanced scale or unbalance an balanced scale.
I don’t understand pharmacology well enough to really know exactly what’s going on, but I’ve always thought today’s ADHD drugs are extremely broad, perhaps even crude solutions to a poorly-understood condition.
Kind of a super broad-spectrum antibiotic versus a narrow-spectrum antibiotic. Today, my (non-medical) understanding is essentially the same as yours, and that we use Adderall and other stimulants to do what you say - push them to the normal side of the spectrum - but at its core it's just messing with dopamine levels.
Having ADHD and being medicated for many years, it's not like the feeling of "being on a drug" ever goes away completely. It's not completely benign like, e.g. taking an allergy pill. It still curbs my appetite, so I have to be careful about scheduling doses (always eat before). There's a bunch of personality changes when the drugs are in my system, mostly stuff that makes you want to just work "heads down" and not talk to anyone, sometimes that's great, sometimes it's not. I wonder if I am less emotional and am more selfish because of being on it so long, I can't imagine telling someone "I miss you", for example, that just seems like an overly-sensitive emotion that I'm not capable of producing. Especially not in a world connected by iMessage and the Internet, where everyone seems like they are right beside you, even if they are thousands of miles away.
Not sure where I'm going with this, but I guess what I meant by "broad action" is that we are kind of killing one person by carpet-bombing. I wonder if in the future we'll have meds that work much better with less side-effects.
Maybe we even have them now in the form of the non-stimulant options, but my doc did not sound enthusiastic about switching from stimulant to non-stimulant ADHD meds.