We used LD score regression (LDSC) (Bulik-Sullivan et al., 2015; Bulik-Sullivan et al., 2015) to estimate the SNP-heritability of DSM-NicDep and the genetic correlations between DSM-NicDep and other substance use phenotypes, using published GWASs of PAU (Zhou et al., 2023), FTND (Quach et al., 2020), ICD-TUD (Toikumo et al., 2024), CPD (Saunders et al., 2022), cannabis ever-use (Pasman et al., 2018), CanUD (Levey et al., 2023), OUD (Deak et al., 2022), SmkInit (Saunders et al., 2022), and smoking cessation (Saunders et al., 2022). We also estimated genetic correlations between DSM-NicDep and other phenotypes, including psychiatric disorders, behavioral traits, respiratory health, and socioeconomic status-related phenotypes. Details on the individual GWAS used in genetic correlation analyses are provided in the Supplemental Methods. We further tested whether genetic correlations for DSM-NicDep and FTND were different from each other using a block-jackknife method (Bulik-Sullivan, Finucane, et al., 2015; Coleman et al., 2020).
