We found little evidence to support multiplicative interactions between the schizophrenia PRS and duration of daily use or age at first cannabis use (supplementary table 5). However, we note that the ascertained nature of the COGA sample and the fact that the overwhelming majority of individuals who endorse cannabis-related experiences in COGA have met the criteria for a lifetime CUD diagnosis (eg, 98% of individuals who report cognitive difficulties have met criteria for a CUD diagnosis) may have influenced our findings. The exclusion of individuals with schizophrenia, by study design, may also have impacted our results. It is likely that this range restriction (ie, few individuals who report cannabis-related experiences without heavy cannabis use and few individuals at the highest end of the spectrum of risk for schizophrenia), coupled with a small sample size, limited our statistical power to identify interactions. It is worth noting that the strongest interaction effect observed, which suggested that polygenic liability for schizophrenia has a greater effect on risk for any cannabis-related experiences in individuals with a CUD diagnosis, was actually stronger in the model
