Do dyadic interventions impact biomarkers of child health? A state-of-the-science narrative review.

BACKGROUND: Early life adversity is related to numerous poor health outcomes in childhood; however, dyadic interventions that promote sensitive and responsive caregiving may protect children from the negative consequences of such exposures. To date, quasi-experimental and randomized controlled trials (RCTs) have examined the impact of dyadic interventions on a range of individual biomarkers in children, which may elucidate the relation between early stress exposure and transdiagnostic risk factors for prospective poor health. However, the content of interventions, analytic strategies, and findings vary widely across studies, obscuring key themes in the science and hindering policy and research efforts.

METHODS: We use a narrative approach to review findings from methodologically rigorous (predominantly RCT) studies of dyadic interventions' impacts on different biomarkers in children, including indicators of the hypothalamic-pituitary-adrenal (HPA) axis, parasympathetic (PNS) and sympathetic nervous systems (SNS), brain development, inflammation, and intracellular DNA processes. We contribute to this important area of inquiry through integrating findings across biological systems and identifying contextual and mechanistic factors to depict the current state of the field.

RESULTS: Evidence suggests dyadic interventions improved PNS functioning and advanced brain maturation. Some studies indicated interventions reduced hair cortisol concentrations, systemic inflammation, and resulted in differences in DNA methylation patterns. Findings did not support main effect-level change in salivary measures of HPA axis activity, SNS activity, or telomere length. Importantly, reviewed studies indicated significant heterogeneity in effects across biological systems, underscoring the importance of contextual factors (e.g., adversity subtype and severity) as potential moderators of effects. Further, findings suggested enhanced parenting behaviors may be a mechanism through which dyadic interventions operate on biomarkers.

CONCLUSIONS: We close with future policy and research directions, emphasizing the promise of biologically-informed dyadic interventions for understanding and ameliorating the effects of early adversity on transdiagnostic biomarkers of health.