I can only speak to ADHD, but there seem to be big differences in scores medicated vs. unmedicated, or even depending on time of day and how concentrated the med is in the bloodstream. DD took a math fluency test in school and her score practically doubled after we increased her med dose (just as one example). Nothing else changed in the meantime. Was it the meds? Who knows, but depending on the condition and how much the med helps, it can be a big factor.