"My brother is having social and school problems, and I'm looking for a program in the NY area that works with the whole family to help him."
I am not as familiar with what is available in the New York area. Try The ADD Resource Center. They may be able to direct you to a program that will address the substance abuse issues as well as have an understanding of AD/HD (They may even have a program themselves).
Their number is (212) 724-9699. They are located at 215 West 75th Street, New York, New York. I admire you loving concern for you brother and your tenacity to help, but please remember to take care of yourself also. Substance abuse can take its toll on family members and both you and your mother may find the support of Alanon a welcome relief and a positive and constructive way to deal with the stress of the situation.