It's possible that ADHD drugs don't boost grades, on average, because grades are a strong function of the home environment. Thus, improving a child's focus wit

It's possible that ADHD drugs don't boost grades, on average, because grades are a strong function of the home environment. Thus, improving a child's focus without improving their home environment won't magically improve their grades. Work is work and there is always something more stimulating a child could be doing in an unstructured environment. ADHD is heritable, so it's possible some parents don't themselves have strong study skills or discipline, value grades, and/or have self selected to take the easy route (drugs) before trying the hard route.