Tbh, his Ketamine use makes me very very happy. He should do it more often.
Why? Ketamine abuse leads to severe damage of the urinary tract system. According to various sources this is already happening - and the damage is irreversible. Patients suffering from them are unable to pee - while having a massive urge to do so (imagine a decade long UTI, with your bladder really filled to the brim but you can't pee physically). And in the end it fucks their kidneys up due to the urine backing up into it. (And no, he can't get a transplant then. As the ureter is the problem and damaged beyond repair there isn't that much that can't be done then)
Furthermore the combination of drugs he admits he takes is a prime setup for a ketamine induced persistent psychosis. Elmo is already showing massive signs of intermittent or persistent psychosis, but things can get worse - far worse for him. Because the combination he takes can sometimes lead to a chronic persistent psychosis with auditory or visual hallucinations, delirium and ongoing psychosis symptoms. In other words: He would get so batshit crazy that a normal person would either be admitted in time and for a long time or kill themselves. In his case it's more likely that his staff would make sure he doesn't kill himself and lock him away. (Kill as in "running over a highway butt naked because the Zombie cows hunt them" or "trying to stop a train by a naruto move")
When I still worked in a psychiatric hospital we gad a similar guy - actually not unintelligent,but fried his brain with a similar mixture. In the end result he needed massive loads of drugs so he wouldn't be in a constant state of panic (mostly because every shadow was a giant spider trying to kill him) but basically made him a zombie. And,as he did a few awful things in this state of terror(setting fire to the psychiatric hospital twice, push a old lady in front of a bus -she was not hurt as the bus was imaginary,too-, stabbing a kindergarten teacher in front of her class) he was with us for years in a locked/high security ward. Aftee that he left us towards a similar ward in a permanent nursing facility.
There is a good chance he won't have a nice retirement life. Which is well deserved.