Current thinking on
Ritalin, based on experimental results is that the
amphetamine-like effects it has are
not responsible for its apparently positive affects in
ADD/
ADHD. It's looking at the moment as though it tends to push up
dopamine levels- this chemical is connected to the reward circuits in the brain. It looks like
ADD/
ADHD people have somewhat lower levels of this chemical, and this drug appears to normalise them.
Still, the amphetamine-like affects are certainly there, and a reasonably good reason to avoid the drug if possible.