Sponsorship of someone with a disability!

I am currently living in the U.S.A. and I am married to a U.S. Citizen.We have filed the I-130 and are waiting for the reply. My husband has a 32 year old son that has a mental disorder and cannot live alone.So he is dependant on us.My Ques. is: If we decided to live in Canada instead, can I apply for him as well as my husband? And would there be any reason that his son would be denied?? I heard that he might possibly be denied! He is a healthy person other than his mental disability! We are considering moving to Canada and I hope someone can help me with this ques..