I remember the following.
In my family there's no history of schizophrenia. Some very distant relative abused strange medicine and ended up getting the gift of madness though. Took several decades.
The spiritual practices can cause a mess. I mentioned it before in some other posts. I had some scenarios a decade or so ago, some friends had the same. The cases were very similar.
How to summarize it...
Imagine that you have always felt normal, no problems but suddenly you feel strange thoughts coming from elsewhere. You are able to understand they are not your own. You might also feel strangely clogged and disconnected from the reality. There seems to be something inside you, perhaps you sense it in the spiritual engine. It wasn't there before. The reality seems different, there's a sense of having a filter between you and the reality. About like some weird delay and a pair of sunglasses. Something is horribly wrong. I remember a sunglasses case, everything was filtered and delayed. The perception was distorted.
You realize something is wrong, any doctor would give you a diagnose and consider you mad. Prescribe something against it and hope it solves the problem but no it wouldn't. Perhaps you start thinking about the previous practices and suddenly you understand that you went too far with some invocations and didn't quite do what you were supposed to. Maybe just maybe you invoked something into yourself...? Maybe that amazing random tutorial you found by a user Promage69420blazeit wasn't so good after all, even though it seemed great.

Maybe you did excessive spiritual practices and caused yourself to become too open. In that open state you did something weird. Some sort of a thing noticed your openness and the easy access. It came through and attached itself. You became visible on their radars.
Your feel thoughts, negativity, aggression, perhaps voices, they aren't your own. Something is awfully wrong. People who hear about it think you have lost your mind. They don't want to do anything with you, you could become isolated. Depression waves attack you, the negative entity wants your emotions. You get an idea to abuse substances to switch off the problems, all planted by the entity so that it could weaken you and gain a higher control. They'd be happy to have a feast over something so vulnerable. To further isolate you and devour as much as possible, perhaps use you for something.
With a better understanding you understand that you must seek help or figure out a way to get rid of the problem. You understand that this is a huge issue but 99% of the people can't understand it.
The longer it lasts the worse it can become. There's a certain level of mind control. A downward spiral.
When you get rid of the problem everything turns normal, just like before. All the symptoms completely disappear. Not a single sign anymore. No filter between the reality, no weird thoughts, no depression, no despair, nothing wrong. Night turns into a day. All normal.