Honestly I think his brain is the worst off. Watching him decay through spice, duster and increasing amounts of alcohol I believe we have already seen his mind go to mush. He has slowed down significantly and its really sad to compare how youthful and energetic he used to be to where he is at now. Nothing really interests him, his level of function is declining in such a way as to appear to be permanent loss, and he becomes further isolated each day. It's really not good and I think that both his mental and physical brain health are worse off than his teeth are. I would not be surprised if it came out that he had a significant level of brain damage, or is at risk of chronic brain disease. For all of the loops and jokes about group homing the boy, it would not surprise me if he required a nursing home by 50.