"i am 23 years old and have been on concerta for over 2 years. i can tell you, as all of you have mentioned, that the first initial response my brain had to this medicine is efficiency. i went from not knowing if i could make it through school, to getting myself back into school after a year or so off. i went to college, and started taking concerta. i had straight as for quite a while. i went from 18 mg, to 27 mg. i have noticed, within the past two years, that my brain has become very used to the drug. i have tried not taking it for a few days, because i don&#039;t want to depend on the medicine. however, i do notice after a couple days off of it, that my mind doesn&#039;t work at all. i feel like my brain is non-functioning; like i can&#039;t do anything."