Cortisol secretion moderates the association between mother–infant attachment at 17 months and child behavior at age 5 years

This study examined infant cortisol secretion as a moderator of the association between mother-infant attachment security at age 17 months and child behavior at age 5 years. A longitudinal community sample of 96 mother-child dyads participated in the strange situation procedure (SSP) at age 17 months. Cortisol was collected at baseline, and at 20 and 40 min post-SSP. Maternal reports of child behavior were collected at age 5 years. Results revealed that the associations between nonsecure mother-infant attachment and higher total, internalizing, and externalizing behavior were stronger for infants with high cortisol secretion, relative to infants with low cortisol secretion. The model of interaction differed depending on the outcome, with diathesis-stress explaining variance in total as well as internalizing behavior, and with differential susceptibility explaining variance in externalizing behavior. These findings augment our understanding of risk and resilience to the impact of the early rearing environment on later psychopathology.