Sure. They had an incredibly bad time with the trip, far worse than what you usually associate with a bad trip. Violence, screaming, paranoia, gibberish. All stuff (maybe apart from the violence) that can happen on a bad one, but this was extreme. Setting was familiar and safe, no external stresses during the period. This was his first time with mushrooms, although regular cannabis smoker (which also might have caused an issue). Regular dose.

The next few days he was still recovering, but thoughts still very scattered and incoherent. Unfortunately this didn't taper off. I had not seen him for a few weeks until his family were in contact. The behaviour had become drastically worse, violence and paranoia. Eventually he was diagnosed with schizophrenia.

From what I have read, with a certain kind of predisposition it would have probably manifested itself later in his life if he was unlucky.

I don't want to put people off Psilocybin as it can be an incredible thing. Just be damn careful and do your research.