Remember how Russell Crowe in Beautiful Mind gradually slid into a paranoid psychosis, letting the audience experience some of the reality-confusion along the way? Ron Howard depicted this process well in that movie; the creepy feeling that things are getting a little strange.
It may not be a general-interest topic, but it is an issue which Psychiatrists are frequently presented. You consult with a late teen or young adult, usually on the urging of a parent, who has shown some decline in functioning and has some new anxieties and some peculiar symptoms.
A seasoned shrink thinks "Hmmm. This smells sort-of pre-psychotic but of course I might be wrong." (Much of medical care is as much art and experience as it is science. Never, ever go to a young doctor.)
Apparently our instincts in this area are right at least 50% of the time, which isn't very good.
This article at Neuroanthropology is excellent: Slipping into psychosis: living in the prodrome.