Marijuana can have an adverse effect on schizophrenia but does not cause it. It does have occasion to cause a form of temporary psychosis in some individuals that subsides if use is discontinued. The Isreali’s are the world leaders on research. http://www.jpost.com/Business-and-Innovation/Health-and-Science/Most-medical-marijuana-users-benefit-from-treatment-finds-Ben-Gurion-University-study-455072 http://www.israel21c.org/israeli-medicine-goes-to-pot/