In COGA, there was especially robust support across ancestries for an association between the schizophrenia PRS and cognitive difficulties (meta-analyzed beta = 0.22, SE = 0.04, P = 5.2e−7). This is consistent with previous studies which have found that schizophrenia PRS are associated with increased disorganized symptom scores and lower cognitive ability,17,18 while weaker associations are reported with other symptom domains. In the European ancestry sample, we created a categorical variable representing quartiles of polygenic risk for schizophrenia; when we regressed cognitive difficulties on this categorical variable of risk, we found that individuals in the top 25% of polygenic risk for schizophrenia had 2 times greater odds of reporting cognitive difficulties after using cannabis, relative to individuals in the lowest quartile of risk (supplementary figure 2). We note that while this may seem like a large increase in risk, there is great uncertainty in PRS models and individual-level prediction is unlikely to be accurate. Of the 5 cannabis-related experiences studied in this report, hallucinations were the least common and the least strongly correlated with the other reported experiences (supplementary figure
