Current results indicated that a subgroup of the sample disproportionally benefited from the intervention. Consistent with genetic differential susceptibility (Belsky et al. 2007; Belsky and Pluess 2009), intervention effects on the linear slope were stronger among AAs carrying C alleles of the NR3C1 SNP rs12655166 than those not carrying this minor allele. The plausibility of this interaction is supported by consideration of the biological function of the NR3C1 gene. Genetic sequence variation at the NR3C1 locus is established as a source of individual differences in glucocorticoid signaling within the HPA axis, a critical mechanism involved in human response to environmental stress and challenge (DeRijk et al. 2008). When confronted with a perceived threat, the hypothalamus initiates a cascade of neuroendocrine signaling that mobilizes the body’s resources toward resolving the threat. One component of this response is the release of the glucocorticoid hormone cortisol, which plays a key role in a negative feedback loop that inhibits further hormone secretion by the hypothalamus, dampens HPA axis activity, and helps to return the body to homeostasis. This inhibitory signaling is mediated by glucocorticoid
