I think he was already quite prolific before that started.

IMO, it is a bit of a myth that Adderall will make an already productive person more productive.

However, stimulants do motivate compulsive behaviors and rigid thinking.

That's where it would have helped Erdos. To just do math everyday and never be much interested in other pursuits takes something extra. Even into old age he didn't have anything else on the bucket list.

A lot of people with neurodivergent brains self medicate to function in the world we are in. It is hardly surprising a math prodigy did so.

I would imagine there are many mathematicians who take ritalin, but I don't see them mentioned as being Paul Erdos.