
What an awful situation for her :(
It's so very difficult. I'm afraid 'tough love' is the only way to go. If he's been smoking dope for a while he'll be getting to (or is already in) the paranoid stage which would account for his mood swings. It's hard when ground rules aren't set out from the beginning and he's going to resent whatever she does to alter the situation. I can't see him being sectioned, the doctors are going down this route less and less and basically, if he's not hearing voices and isn't presenting a physical danger to others they won't do it.
Your Aunt could contact the charity
"MIND" (the National Association for Mental Health) and they could guide her as to what to do next. She definitely needs to see someone professional about this.
I do hope she, and her son, gets some help soon.
Debs