Ok since you stuck around for a bit more than a one time post and have read and responded with some actual thought on the subject, I will put some effort into replying to you.
Your friend sounds like a familiar story. Schizophrenia is a physical difference in the brain - something is going on in the brain that the majority of the population doesn't experience normally / regularily and (I believe) cannot relate to. Psychosis like symptoms can stem from psychological experiences - i.e. there is not a physical change to the neurological "structure" of the brain - meaning thought itself is responsible, not the physical make up of how your brain functions. This realization in conjunction to what brain eater is saying (the more spiritual side of things) is extremely important.
The problem with these subjects is how do we know that your friend is experiencing the oncoming of schizophrenia (a physical difference in the brain) or simply having trouble dealing with reality's wake up call? The identification of which scenario is going to play out could be the difference between putting your friend in a dissociation with the world, or the possibility of a breakthrough in which he realized what exactly he is 'missing' or subjectively blind to.
... I feel bad for repeating this story so many god damn times to the people who have heard it, but its important. I was in your friends shoes about 5 or 6 years ago. I was having psychotic behavior, swinging thoughts, racing logic, delusions etc while high on marijuana. Due to my inability to u nderstand what was going on, I became interested in psychology and beyond - I eventually took psilocybin one night. It was dreadful [extremely agonizing]. I didn't learn jack shit to improve my well being. In fact, it made the problem incredibly hard to deal with. I had to put off marijuana, even alcohol would bring on psychotic delusions. An important thing was that these thoughts weren't really untrue, the context and the feeling that accompanied them were just extremely unpleasant. My ambition to learn and recover from my psychological position drove me to this site and others in a quest for .what the fuck. was happening to me.
To be honest, I still cannot say what happened, what is happening, or what to make of it all. However, on my journey from then to now created a deep understanding of the duality of my mind and existance. I became a more balanced person with meditation, reading, and a lot of questions slowly being answered (or the realization that the questions can't be answered). Perhaps if I had not had the ambition to understand and continue to experience (and fight) with the going-ons in my head, I may have been administered anti-psychotics and put in a hospital and eternally thinking I had a 'disorder'. I do not know if that would have been an alternate path or not, I do not know these things!
The important thing is to not take acid or mushrooms with the expectation of curing yourself or his-self... You must have no expectations, and be ready for anything. A bad trip while high is quite uncomfortable, but a a bad trip while your sober is on a different level - you can no longer simply put it in the back of your mind as an odd or bad experience - it becomes your experience.
BOY DON'T I SOUND LIKE THE WORST.
I don't like saying that kind of stuff, I think it may set you off on the wrong track, or derail you into fear. I don't want that, but I do want this to be known.
Having said all that - I hadn't had euphoria in about 4 years after the negativity started. One day I tripped, but prior to ingestion I said "I want to experience love". I was blasted with cascading hearts, love, warmth, motherly love and care. I felt taken care of, completely safe, happy, joyful, giggling. Once I came down I felt an understanding I hadn't seen before. All along I was searching for healing and love deep within the pain and fear. If I had only turned around, and looked somewhere else, would I have been presented with it so much sooner.
The duality of the mind is... well, very powerful.
So what is the summation of all this? I don't know. The difference between my psychotic state and a schizophrenic is I would not have believed if Jesus suddenly appeared to me and told me to do things. A schizophrenic would be much more likely to believe such an image.