The mediation analyses revealed that EC strength from the right NACC to left pre-SMA mediated the association between addiction severity (MAST scores) and impulsive scores (Sobel test: t = 2.48, P = 0.013, a bootstrap resampling analyses of the effect size indicated that these mediation effects were different from zero (95% confidence intervals: 0.097–0.536); Fig. 8A). We also attempted to examine alternative models, such as utilizing impulsive scores as the dependent variable and addiction severity as the independent variable; however, none of these models yielded statistically significant mediation effects. We also observed that EC strength from the right dACC to right putamen mediated the association between addiction severity (MAST scores) and compulsive scores (Sobel test: t = 2.42, P = 0.015, a bootstrap resampling analyses of the effect size indicated that these mediation effects were different from zero (95% confidence intervals: 0.090–0.520); Fig. 8B). We also attempted to examine alternative models, such as utilizing compulsive scores as the independent variable and addiction severity as the dependent variable; however, none of these models yielded statistically significant mediation effects.
