To examine how vmPFC activation and negative urgency relate to alcohol craving and problematic alcohol use, we conducted a series of mediation analyses using the INDIRECT SPSS macro provided by Preacher and Hayes (2008). This analysis uses the product of coefficients approach and bootstrapping to examine indirect effects; confidence intervals (90%) that do not contain zero are considered significant indirect effects. Negative urgency significantly mediated the effects of L vmPFC [AcO > SO] responses (b = 0.18, SE = 0.14, 90% CI [0.04, 0.55]) and R vmPFC [AcO > SO] responses (b = 0.23, SE = 0.13, 90% CI [0.05, 0.48]) on subjective alcohol craving. The reverse mediation (vmPFC activation mediating the effects of negative urgency on subjective alcohol craving) was not significant. Negative urgency also significantly mediated the effects of L vmPFC [AcO > SO] activation (b = 0.40, SE = 0.39, 90% CI [0.06, 1.37]) and R vmPFC [AcO > SO] activation (b = 0.54, SE = 0.32, 90% CI [0.17, 1.21]) on problematic alcohol use (AUDIT total score). The reverse mediations (vmPFC activation mediating the effects of negative urgency on AUDIT) were not significant. Figure 7 depicts these meditational analyses.
