Caregiving and 5-HTTLPR Genotype Predict Adolescent Physiological Stress Reactivity: Confirmatory Tests of Gene 9 Environment Interactions

A theory-driven confirmatory approach comparing diathesis–stress and differential susceptibility models of Gene 9 Environment (G 9 E) interactions was applied to examine whether 5-HTTLPR genotype moderated the effect of early maternal caregiving on autonomic nervous system (ANS) stress reactivity in 113 adolescents aged 13–17 years. Findings supported a differential susceptibility, rather than diathesis–stress, framework. Carriers of one or more 5-HTTLPR short alleles (SS/SL carriers) reporting higher quality caregiving exhibited approach ANS responses to a speech task, whereas those reporting lower quality caregiving exhibited withdrawal ANS responses. Carriers of two 5-HTTLPR long alleles (LL carriers) were unaffected by caregiving. Findings suggest that 5-HTTLPR genotype and early caregiving in interaction are associated with ANS stress reactivity in adolescents in a “for better and for worse” fashion, and they demonstrate the promise of confirmatory methods for testing G 9 E interactions.