Abstract
OBJECTIVE: Exposure to stress during critical periods of development can diminish stress reactivity by the hypothalamic-pituitary-adrenocortical axis. Genetic characteristics may further modify this effect of early adversity, leading to a gene by environment (G × E) interaction on stress reactivity in adulthood. Val-allele carriers of a common polymorphism of the COMT gene (Val158Met, rs4680) have rapid removal of catecholamines in the prefrontal cortex, limbic system, and reward centers. Carriers of the Val and Met alleles may therefore respond differently to the environment and differ in the long-term impact of exposure to early life adversity (ELA). METHODS: We measured saliva cortisol reactivity to public speaking and mental arithmetic stress in 252 healthy young adults exposed to low, medium, and high levels of ELA and who were genotyped for the Val158Met polymorphism. RESULTS: Cortisol responses showed a G × E interaction (F(4,243) = 2.78, p = .028); simple effects tests showed that Met/Met carriers had progressively smaller cortisol responses with greater levels of ELA. In comparison, Val/Val homozygotes had blunted responses that did not vary with ELA exposure. CONCLUSIONS: Met/Met homozygotes seem sensitive to stressful events in childhood and adolescence, leading to environmental programming of the stress axis. Glucocorticoid responsivity may represent a common pathway revealing targeted genetic vulnerabilities to the long-term effects of early life stress. The results suggest that further G × E studies of ELA are warranted in relation to health behaviors and health outcomes in adulthood.