I think the question above was about side effects, is there a reason to believe they are any different with and without ADHD?

Even regarding the main effect, my understanding is that it's "concentration boost" in both cases, just seen more socially acceptable for people who lack concentration in the first place. Is there any study that would demonstrate the difference?

that seems unlikely. I was looking into it the other day out of curiosity because of ADHD being . The effects of the same dosage on someone without ADHD is pretty much the same as with, it makes people feel more focussed.