> All of these are also side-effects of over use of amphetamines...

Surely you are not the first person with this idea? Could it be that other people thought this too and compared unmedicated and medicated ADHD populations?

ADHD is heavily underdiagnosed in the adult population, hence it is not hard to find adults who have ADHD and who never took stimulants. IIRC, The studies show that kids medicated with stimulants actually have lower rates of substance abuse.