Paranoid Schizophrenia is a hell of a hard disease to deal with when your friend gets it.
My friend developed it a few years ago when we were working on a company together. He was about at the age of onset.
I have dealt with a lot of diseases among my friends including drug addiction, depression, anxiety, but of them all Schizofrenia is the hardest because even if they want to they cant understand or listen to reason, so no words or even actions can be effective most of the time.
Its a hell of a disease and worse yet him as someone who is suffering with it has lost almost all of his friends and it isnt helping him mental health or ability to correct the problem.