Linear or logistic regression models using LESS Highest Impact, amygdala reactivity, VS activity, and their interactions as independent variables, and AUDIT or AUD diagnosis as the dependent variable, respectively, were conducted in IBM SPSS Statistics 21 (IBM, Armonk, NY). Significant three-way stress x amygdala reactivity x VS activity interactions where probed by testing the significance of the slope linking LESS and AUDIT or AUD diagnosis at low (1 SD below the mean), intermediate (mean), and high (1 SD above the mean) levels of amygdala reactivity and VS activity as implemented in Model 3 of the PROCESS macro43 for SPSS. To more comprehensively depict the moderating effects of amygdala and VS reactivity across the entire range of their respective distributions, we further estimated the beta coefficient linking LESS and AUDIT at all observed amygdala and VS activity values. The distribution of AUDIT scores was slightly positively skewed (skewness = 0.963, kurtosis = 0.833). Nonetheless, skewness and kurtosis of this magnitude are still below the recommended cut-off for linear regression analysis,44 thus we have conducted all our analyses using raw AUDIT scores.
