In the current study, released in the journal Psychological Medicine in December 2024, researchers mined the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) study data, from 2018, as well as data from the UK Biobank to determine risk for psychosis caused by two factors. The goal was to establish how cannabis use and underlying genetics connected with schizophrenia risk (“genetic load”) might combine to increase the risk for psychosis in affected individuals, and also how genetic load alone affected said risk. Heavy cannabis use had already been definitively demonstrated to increase the risk of psychosis, while the role of genetic load remained unclear.
The researchers used statistical measures from the Psychiatric Genetics Consortium and the Genomic Psychiatric Cohort to examine the schizophrenia and cannabis use disorder (CUD) schizophrenia polygenic risk score (PRS) for a total of 144,698 individuals. They discovered that both genetic load and heavy cannabis use independently increase psychosis risk, but that the two factors are not associated with each other; nor do they interact to increase the PRS of the affected individuals. High-potency cannabis use or daily cannabis use caused the highest odds of an individual presenting with psychosis.
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