severity of cannabis-related experiences as indexed by a greater number of experiences endorsed. Third, we analyzed a variable assessing duration of daily cannabis use—self-reported the longest period of time an individual used marijuana almost every day—but this may not be an ideal measure of the heaviness of use. Beyond limitations associated with self-report, this measure does not capture quantity nor potency, and any “noise” captured by this variable may have contributed to its weaker associations with cannabis-related experiences. Fourth, no data on the potency of cannabis used was available, and there is evidence that the ratio of THC to cannabidiol can vary widely in available cannabis across the US55,56; there is a possibility that varying levels of cannabis potency and THC:cannabidiol ratio could have affected our results. Fifth, we only examined the genetic risk for schizophrenia, but some of the cannabis-related experiences analyzed—psychosis, anhedonia, and social withdrawal—are common features of other disorders, including bipolar disorder and depression, for which we did not examine polygenic liability. Sixth, while individuals with psychotic disorder diagnoses were excluded from the COGA cohort,21 new onsets of psychotic disorders may have been missed as the SSAGA does not evaluate these diagnoses. However, these are expected to
