As expected, the estimated coefficients from models of the CES-D score indicate sizeable main effects for trauma and major life events, but the main effects for 5-HTTLPR are not significant (Table 3). The GxE interactions are significant for trauma (p<0.05 based on a Wald joint test) but not major life events. As depicted in Figure 1, there is little genotypic variation in predicted depressive symptom scores among persons who experienced one or no traumatic event. However, among those exposed to at least two traumas, predicted CES-D scores are higher for individuals with the S/S and S/L genotypes than other genotypes. The differences between persons with S/S or S/L genotype and those with L/L or L/XL genotype are significant (p< 0.01) and large—about one standard deviation in the score (5.5 points). The significance of the GxE interaction with trauma but not with major life events suggests that the interaction may be more prominent with exposure to extreme stressors.
