Sample characteristics of participants with alcohol dependence and controls in the ENIGMA-Addiction and UKB are shown in Table S6. As shown in Figure 3A and Tables S7, participants with alcohol dependence, when contrasted against controls, showed a widespread pattern of thinner CT in both UKB and ENIGMA-Addiction (r=0.58, p-spin<0.001). As shown in Figure 4, effect size maps obtained from the analyses with and without PC1 removed showed significant correlations in the ENIGMA (r=0.78, p-spin<0.001) and UKB (r=0.81, p-spin<0.001) datasets. However, the number of significant regions associated with alcohol dependence dropped from 52 to 1 in the ENIGMA dataset and dropped from 50 to 5 in the UKB dataset after removing PC1, suggesting that the observed group differences in the original analyses were largely driven by PC1. Detailed statistical results are reported in Table S8 and Table S9.
