Caregiving quality modulates neuroendocrine and immunological markers in young children in foster care who have experienced early adversity

Background Early adversity is believed to alter the body's stress-response systems, putting children at increased risk for somatic and mental health problems. However, it remains unclear whether such alterations normalize under improved caregiving experiences. Thus, the goal of the present study was to investigate (a) whether children in foster care show endocrine and immunological alterations relative to children living with their biological families, (b) whether these alterations change over time spent with the foster family, and (c) whether the alterations are modulated by current caregiving experiences. Methods A total of 94 children in foster care and 157 biological children, aged two to seven years, took part in a longitudinal study with three assessments conducted over a 12-month study period. At the initial assessment, children lived for an average of 18 months with their current foster families. Children's cortisol, dehydroepiandrosterone (DHEA) and progesterone concentrations and cortisol/DHEA ratios were measured in scalp hair and children's secretory immunoglobulin A (sIgA) levels in saliva. Caregiving quality was assessed based on caregiver-reports and observational measures of caregiver-child interactions. Results Children in foster care had lower cortisol/DHEA ratios and higher progesterone concentrations than biological children, while no group differences were found for cortisol, DHEA or sIgA. Time spent with the current foster family did not significantly influence the child's endocrine or immunological markers. Importantly, caregiving quality modulated cortisol/DHEA ratios and sIgA concentrations: children in foster care of lower caregiving quality had lower cortisol/DHEA ratios than children in foster care of higher caregiving quality and showed decreasing, rather than increasing, sIgA concentrations across the study period. Conclusions Our results indicate that caregiving quality in the foster family may have an important modulating effect on selected indicators of the child's stress response and could thereby mitigate the possible consequences of early childhood adversity.