If IQ is real how come I can give a daily dose of stimulants to someone who suffers from it and suddenly they go from bottom of the class to top?

Isn’t executive function the thing we call IQ? Working memory etc. Even a few weeks back a new much shorter IQ test was developed for people with adhd and they found their scores were higher this time, turns out due to their executive dysfunction issues they can’t keep on task for how long a standard IQ test lasts. Why does science lack common sense at times? Shouldn’t this have been obvious? I personally know people who went from bottom to top of the class after being given medicated and there’s no lack of accounts online.