Abstract
Foster children exhibit high rates of atypical neuroendocrine functioning compared to children in the general population. In particular, alterations in the daytime diurnal activity of the hypothalamic-pituitary-adrenal (HPA) axis have been observed in foster children, often characterized by blunted salivary cortisol levels (i.e., low morning levels that remain low throughout the day). There is emerging evidence that therapeutic interventions for foster children can affect this pattern of HPA axis activity, but the specific intervention components responsible for change have not been fully explicated. Within a randomized trial to evaluate a therapeutic intervention for foster preschoolers (n = 57 intervention condition; n = 60 comparison condition; n = 60 community comparison condition), the present study examined whether diurnal cortisol activity was associated with caregiver self-reported stress in response to child problem behavior. Results showed immediate reductions in caregiver stress that were sustained through 12 months postbaseline in the intervention condition. In contrast, caregivers in the regular foster care condition showed higher rates of stress across time and increased stress sensitivity to child problem behaviors. In addition, among caregivers in regular foster care, higher self-reported stress was associated with lower morning cortisol levels and more blunted diurnal cortisol activity. These results provide evidence that interventions can simultaneously impact caregiver stress and buffer children from the negative impacts of caregiver stress on HPA axis regulation.