A PRS was computed from the iPSYCH CUD GWAS summary data using the LD-pred method73. Only markers with a single rs-name from the GWAS were used. Associations between the PRS and CUD (2,257 cases and 145,069 controls), schizophrenia (729 cases and 153,007 controls), bipolar disorder (1,751 cases and 151,923 controls) and smoking (46,941 individuals reporting being a regular smoker in their life and 20,602 controls that has never been regular smokers) was computed using linear regression. Covariates were sex, age and the first 10 principal components. Association P-values were corrected for inflation using LD-score regression.
