so many top level mathematicians use amphetamines
Do you have a reference for that? I know about Erdos [spelled wrong because Slashdot can not handle Unicode and I'm too lazy (no speed) to see if there is an HTML entity for what should be here], because I read his biography My Brain is Open: he could not do mathematics without speed. But I'd not heard that it was a widespread phenomenon.
you give it to them. If their symptoms go away they need it, else they don't
In fact, it is just this flawed methodology that created the false idea in the minds of researchers that speed was actually helping these children. This false idea is what has led to the current massive overprescription and probable consequent harm to millions of patients.
Radioactive cats have 18 half-lives.