My son (who is now an adult) has Asperger's Syndrome and was prescribed Ritalin for ADHD when he was about ten years old. He lost a considerable amount of weight - too much for a growing boy, became incredibly picky with food and had a lot of trouble sleeping (although a lot of that could be attributed to ADHD - but something to be aware of).

Having said that, if you don't have ADHD, the effects are probably quite different and I wish you well with it. I have hear of its use for MS before.

Good luck and let us know how you go.

Cheers

Lyn