The present findings should be interpreted considering some limitations. The GWAS for BIP and SCZ may include cannabis users, which could bias the current findings. The power of CUD GWAS is limited, which further confines the shared locus discovery, MR analyses, and the prediction efficiency of CUD PGS. The exclusion of LD regions and the removal of the overlapping UK Biobank sample in BIP GWAS may affect power of the conjFDR analyses. Further, shared loci require validation in independent cohorts for cannabis phenotypes. Also, we only focused on the possibility for boosting prediction efficiency on psychotic disorders by integrating the PGSs of cannabis phenotypes. This decision was based on available data in the TOP sample, but the analyses also have potential for greater clinical utility than the prediction of cannabis phenotypes. We use “psychotic disorders” as a general term, but psychosis is not a defining feature of BIP. Therefore, most analyses relate cannabis use to SCZ and BIP, not psychosis. However, psychiatric disorders, such as depression, have been genetically associated with cannabis use and have a relevant links to psychosis.
