Importance: A number of interventions for at-risk children have shown benefits for children's hypothalamic-pituitary-adrenal axis activity immediately after treatment. It is critical to examine whether such changes are maintained over time, given that physiological regulation is implicated in later mental and physical health outcomes.
Objective: To examine whether differences in diurnal cortisol production between children receiving the active parenting intervention and children in the control group persisted at a preschool follow-up (approximately 3 years following intervention).
Design, setting, and participants: Between-subject comparison of cortisol patterns among 2 groups of children (experimental and control groups) involved with Child Protective Services following allegations of neglect. The participants included 115 children (43.5% female) between 46.5 and 69.6 months of age (mean [SD], 50.73 [4.98] months) who had been previously randomly assigned to either the Attachment and Biobehavioral Catch-up (ABC) intervention (n = 54) or the control intervention (n = 61).
Interventions: The experimental ABC intervention focused on 3 aims: increasing parental nurturance to child distress, increasing synchronous interactions, and decreasing frightening parental behavior. The control intervention provided educational information about child development to parents. Both interventions were manualized and involved 10 sessions implemented by a trained parent coach in the families' homes or other places of residence.
Main outcomes and measures: Salivary cortisol samples collected at waking and bedtime for children on 3 separate days.
Results: Analyses revealed significant differences in cortisol production at the preschool follow-up, such that children in the ABC intervention group showed more typical patterns of cortisol production than children in the control intervention group. Specifically, children in the ABC group exhibited higher mean (SD) log-transformed morning levels than children in the control group (-0.87 [0.45] vs -1.05 [0.43] μg/dL, respectively [to convert to nanomoles per liter, multiply by 27.588]; β = 0.18; P = .03). Bedtime cortisol levels did not differ significantly between the ABC and DEF groups (mean [SD], -1.19 [0.49] vs -1.17 [0.48] μg/dL, respectively; β01 = -0.01; P = .87). Those in the ABC group showed a steeper decline in cortisol across the day (mean, -0.31 μg/dL) than those in the control group, who showed a blunted cortisol rhythm (mean, -0.12 μg/dL) (β = -0.19; P = .02).
Conclusions and relevance: Differences in cortisol production between the experimental and control groups persisted at the preschool follow-up and resembled differences initially observed 3 months following intervention. This is encouraging evidence that the ABC intervention for Child Protective Services-referred children may have long-lasting effects on a physiological stress system critical for health and adjustment.
Trial registration: clinicaltrials.gov Identifier: NCT02093052.