Marijuana intoxication is associated with transient psychosis-like effects, including paranoia, ideas of reference, flight of ideas, pressured thought, disorganized thinking, persecutory or grandiose delusions, and auditory/visual hallucinations (46). Chronic daily use of marijuana has been associated with the emergence of a persistent psychotic disorder indistinguishable from schizophrenia (46), although a causal link remains controversial. The current evidence suggests that marijuana use may be a “component cause” in that it is neither necessary nor sufficient to cause schizophrenia (83). Like other negative effects of cannabis, the risk of psychosis appears to be heightened by heavy and early use (84). Large epidemiological studies have shown a dose-dependent risk for chronic psychosis as a result of marijuana exposure (83). Clearly, most people who consume marijuana do not experience psychosis; the marijuana–psychosis link may be mediated through genetic [COMT mutation (85)] and environmental [childhood maltreatment (86)] factors. With the rising potency of marijuana strains, there is some evidence that rates of first-episode psychosis are also rising (87). Further, among persons with established psychotic disorders, marijuana use is associated with a worse course of illness
