As for schizophrenics, the problem there is that once they feel they are feeling better, they stop taking their meds so it's a continuously vicious circle because you have to keep fighting with them to take their meds.
I have a second cousin that can't hold a job because of this. The moment he feels better and stops taking his meds the 'sticky' side of him comes out (where he thinks he has a right to demand what you are doing, why you haven't called, invites himself wherever you go) and people start feeling that he's a freak. There are like 20 locks on his front doors and everyone is an FBI agent (but we're in Canada). The difference with him is that he likes going out and talking to people - he just doesn't make sense sometimes. He thinks martians took a good bunch of his sperm and impregnated all the women around him.
It's really sad because maintaining a normal life for the entire family becomes impossible.
Good luck to your friend.