The brains of shizofrenics realy look different. Schizofrenia is realy a sort of brain damage. Psychedelics don't cause that kind of damage. When somebody had this type of brain damage and then suddenly got crazy after taking pyschedelics it's just that the schizofrenia was dorment. Most people who suddenly have a breakthrough of schizofrenia had sypmtoms before that could have been seen as a warnig sign; often people get realy depressed before it breaks through, they often tend to suddenly neglect themselves dramatically (not washing themselves anymore or changing clothes etc.),often they have shown a paranoïd way of thinking before or strange obsessions or fears. When you feel unstable or have any of these kind of symptoms you should just stay away from any mind altering substance. Most of the people who get crazy after taking some type of drug took amphetamines or coke, btw. psychedelic tryptamines are statistically relatively safe. Cannabis has a much greater chance of triggering psychosis.