Lead: The impact of schizophrenia genetic load and heavy cannabis use on the risk of psychotic disorder in the EU-GEI case-control and UK Biobank studies

The impact of schizophrenia genetic load and heavy cannabis use on the risk of psychotic disorder in the EU-GEI case-control and UK Biobank studies

Psychological Medicine

Using data from the EU-GEI case-control study and UK Biobank, researchers examined the independent and combined effect of heavy cannabis use and schizophrenia polygenic risk score (PRS), on risk for psychosis. Schizophrenia PRS and cannabis use independently increased risk of psychosis. Schizophrenia PRS was not associated with patterns of cannabis use. It was associated with lifetime and daily cannabis use without psychosis, but the effect was substantially reduced when cannabis use disorder (CUD) PRS was included in the model. Regular users of high-potency cannabis had the highest odds of being a case independently of schizophrenia PRS. Regular use of high-potency cannabis remains a strong predictor of psychotic disorder, independent of schizophrenia PRS. Schizophrenia PRS does not seem to be associated with heavy cannabis use. These are important findings, at a time of increasing use and potency of cannabis worldwide. 

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