I have a neighbor who has schizophrenia. He told me that he developed it after years of smoking pot. His meds weren’t working for him a few months ago and I had to call an ambulence for him because he was standing out side his duplex wearing only a T-shirt and doing other weird things.
In this case it was apparently alcohol poisoning that was the trigger for the onset of schizophrenia. People that know him report that he had to be taken to the hospital, and after that he was never the same.