The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study
Di Forti M, Quattrone D, et al. Lancet Psychiatry. Open Access Published:March 19, 2019DOI:https://doi.org/10.1016/S2215-0366(19)30048-3
Although some argue that legalising cannabis is a good idea, this study demonstrates that countries in which high potency cannabis is more available have higher rates of psychosis than those in which it is less available. The authors estimate that if high potency cannabis is banned, 12.2% of cases of psychosis could be avoided.
https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext