Di Forti M, et al. - In order to measure how cannabis use relates to incidence of psychotic disorder, researchers examined patterns of cannabis use with the strongest influence on odds of psychotic disorder across Europe, and if differences in incidence rates of psychotic disorder could be related to variations in such patterns. From 11 sites, data from 901 patients aged 18–64 years with first-episode psychosis and 1,237 population controls were obtained. The 11 studied sites showed striking variation in the incidence of psychotic disorder that could be attributed to differences in frequency of daily cannabis use and in use of high-potency cannabis. Increased odds of psychotic disorder was seen with daily cannabis use vs never users; these odds increased to nearly five-times with daily use of high-potency cannabis. The findings seem to have important implications for public health in view of the rising availability of high-potency cannabis.