It's been a few years, but I believe the problem with ADHD kids is that their brain is in the phase little kids have at the end of the day where they get unfocused and hyper just before they fall asleep.
The Ritalin brings their brain up a notch. If you don't need it, it can bring it up too much. But there are adults on Ritalin since the problem is not always outgrown or they don't learn to cope with it. I've know a few adults who should have been on it!
I may have the details wrong, so someone correct me if so.
I guess for the college crowd it is easier and cheaper to get from the campus docs than “speed” (diet pills) used to be in my time, or smoking - if you remember the days when cigarettes used to be the ADHD self-medication of choice
yes true ADHD kids are affected the opposite way by stimulants- it slows them down