I personally would recommend a non medication approach first (therapy, etc) , and try to hold off on meds
like ADs for
a few years if possible. In the early 20's, those meds will work much more like thaey are supposed to. Just my opinion.
No matter what, be sure he is being cared for by a child/adolescent psychiatrist, not an adult psych. There is a BIG difference.
Best of luck, let us know how he is doing.