Problem Peers for Teens with ADHD

"My 16-year-old son has been diagnosed with ADHD. He has a difficult time making friends and maintaining them. Recently he has started being around negative peers that do drugs and have been arrested. Yesterday I found a gun hidden in his closet, and now I am afraid for my son's safety and future. He has been seeing a psychiatrist who prescribes medication but I think he needs counseling or a boarding school."