Examining associations between internalizing behaviour, cortisol reactivity, and physiological coordination, in two differentially potent challenges

Abstract

Background: Research examining associations between child internalizing behaviours and cortisol reactivity is equivocal, with studies suggesting positive, negative and non-significant associations. The present study assessed three primary confounds that contribute to these inconsistencies: 1) the differential effectiveness of laboratory challenges in eliciting cortisol reactivity; 2) the impact of coordination between the Hypothalamic-Pituitary-Adrenal axis and the Sympathetic-Adrenal-Medullary system (assessed via salivary alpha-amylase (sAA)); and 3) variation in the measurement of internalizing behaviour, specifically, parent versus child ratings. The primary aims of this study were to assess internalizing behaviours in relation to both cortisol reactivity and coordination between cortisol and sAA, measured in two distinct challenges. Method: A community sample of 8-10 year olds (N= 52) participated in two laboratory challenges, across two study sessions: 1) the Trier Social Stress Test-Child Version (TSST-C), a potent social-evaluative challenge, and 2) a less-potent competition challenge, composed of a puzzle and mirror-tracing task. Saliva was collected at several time points before and after each challenge. Saliva was later assayed to extract cortisol and sAA. Child-reported depressive symptoms were assessed using the Child Depression Inventory, and maternal-reported internalizing problems were assessed using the Child Behavior Checklist. Multilevel modelling was conducted using Hierarchical Linear Modeling. Results: In the TSST-C, child-reported depressive symptoms were significantly associated with a declining cortisol trajectory. Maternal-reported internalizing problems were not associated with cortisol and internalizing behaviour did not moderate the impact of sAA levels on cortisol levels (i.e., coordination) in the TSST-C. With regards to the competition challenge, maternal-reported internalizing behaviours predicted cortisol-sAA coordination, such that children with more internalizing behaviours who experienced higher sAA levels also had higher cortisol reactivity. However, there were no significant associations between child-reported depressive symptoms, cortisol reactivity, or coordination between sAA and cortisol reactivity in the competition challenge. Conclusions: Results are discussed in the context of allostatic load and in relation to theories of physiological coordination. These findings underscore the importance of differential stressor contexts, physiological coordination, and the informant of internalizing behaviours moderating associations between internalizing behaviour and cortisol reactivity. Future research should integrate these factors in models of physiological stress and developmental psychopathology.