SU132CANNABIS USE AND SCHIZOPHRENIA: CAN GENETICS TELL IF IS IT "THE CHICKEN OR THE EGG"?

Background: Cannabis use remains the most widely used recreational drug worldwide. In the USA several states have legalized its used and in some for medicinal use. Nevertheless, a significant amount of Epidemiological and experimental studies have reported that cannabis use, especially frequent use of high potency varieties, increases the risk of psychosis. Therefore, it becomes a research priority to identify those individuals at greatest risk to develop psychosis following cannabis use. Methods: Using the genetic and cannabis use data from a large first episode case-control study (N=2300), we aim 1) to use Polygenic Risk Scores for Psychosis (PRS) to test if genetic load for psychosis increases the individual vulnerability to the psychotogenic effects of cannabis; 2) to test if those with high PRS for psychosis are also more likely to smoke cannabis and with high frequency. Results: Subjects with a PRS for schizophrenia in the highest quartile had a 7-fold increase in the odds to suffer from a psychotic disorder (Adj OR=7.0; 95% CI 3.46-14.25). Regular, users of high potency cannabis did not differ on PRS profiles from occasional users or never users (Pearson chi2(3) = 5.6001 Pr = 0.133). We did not find a significant interaction between PRS X cannabis use in influencing risk to Psychosis. Discussion: Summary scores, such as PRS for Schizophrenia, do not explain individual susceptibility to the psychotogenic effects of cannabis. More research is needed to investigate the role of genes mapping at biological plausible pathways. Disclosure: Nothing to disclose.