As I have said many times prior, Cannabis use causes adult onset schizophrenia to come on MUCH faster if you are genetically predisposed to it. Additionally, finding Cannabis in an individual's system usually only confirms that they used Cannabis within the last 30-90 days. I can easily envision many situations where someone would use cannabis and do something insane. If you are already very unstable, and you use cannabis, there is a good possibility that it is going to do make you a lot worse. It will pretty much amplify any emotion, thought, or perseveration of yours, and if you are not in a good healthy space, then it will not bring you good, healthy things.