G × E interactions were explored by considering each measure of adversity (family adversity or stressful life events) separately. Interaction terms were derived as the product of genetic and adversity variables treated as continuous variables. The presence of an interaction can be interpreted as modification to the adversity trend for continuous measures or as a non-additive effect to the presence/absence of adversity for dichotomous measures. Dose response models in which the number of high activity alleles is used as a linear covariate were used to explore G × E interactions. For interactions, the estimated regression coefficient reflects a modification to the adversity trend for a single high activity allele.
