Abstract: This study examined the development of baseline autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) physiological activity from 12 to 36 months as well as antecedents (poverty) and consequents (behavior problems) of individual differences in physiological development. Children (N=179; 50% poor; 56% African American; 52% male) provided saliva samples at 12, 18, 24, 30, and 36 months of age. Latent growth curve models indicated that nonlinear change was evident for both sAA and cortisol, with sAA increasing and cortisol decreasing with age. Children residing in poor households exhibited lower initial levels of sAA, but not cortisol. African-American children showed slightly smaller decreases in cortisol over time. Initial levels of sAA predicted higher levels of internalizing behaviors at 36 months and both initial levels of and total change in sAA predicted higher levels of externalizing behaviors at 36 months. There was no evidence that sAA or cortisol mediated the relationship between poverty and later behavior problems.
Abstract: Numerous studies link harsh discipline to adjustment problems in youth, yet not all individuals exposed to harsh discipline develop behavior problems. Contemporary theory suggests that this relationship could be moderated by individual differences in environmentally sensitive biological systems. This study investigated whether the interaction between hypothalamic-pituitary-adrenal (HPA) activity and autonomic nervous system (ANS) arousal moderated the link between harsh discipline and behavior problems. Three saliva samples were collected on a single day from 425 inner city youth (50% male, age 11-12 years, 80% African American) and were later assayed for cortisol (HPA) and alpha-amylase (ANS). Problem behavior was assessed by self- and parent-report using the Child Behavior Checklist. Youth also reported the level of harsh discipline that they experienced. Harsh discipline was positively associated with externalizing and internalizing problems only when there were asymmetrical profiles of HPA activity and ANS arousal. This pattern was evident for boys but not girls. Findings are discussed in relation to prevailing theories suggesting that biological susceptibility translates adversity into risk for behavior problems.
Abstract: Individual differences in the psychobiology of the stress response have been linked to behavior problems in youth yet most research has focused on single signaling molecules released by either the hypothalamic-pituitary-adrenal axis or the autonomic nervous system. As our understanding about biobehavioral relationships develops it is clear that multiple signals from the biological stress systems work in coordination to affect behavior problems. Questions are raised as to whether coordinated effects should be statistically represented as ratio or interactive terms. We address this knowledge gap by providing a theoretical overview of the concepts and rationales, and illustrating the analytical tactics. Salivary samples collected from 446 youth aged 11-12 were assayed for salivary alpha-amylase (sAA), dehydroepiandrosterone-sulfate (DHEA-s) and cortisol. Coordinated effect of DHEA-s and cortisol, and coordinated effect of sAA and cortisol on externalizing and internalizing problems (Child Behavior Checklist) were tested with the ratio and the interaction approaches using multi-group path analysis. Findings consistent with previous studies include a positive association between cortisol/DHEA-s ratio and internalizing problems; and a negative association between cortisol and externalizing problems conditional on low levels of sAA. This study highlights the importance of matching analytical strategy with research hypothesis when integrating salivary bioscience into research in behavior problems. Recommendations are made for investigating multiple salivary analytes in relation to behavior problems.
Abstract: This study evaluated continuity and change in maternal-child hypothalamic-pituitary-adrenal axis attunement in early childhood. Participants were drawn from a prospective study of 1,292 mother-child dyads, which were racially diverse, predominantly low-income, and non-urban. Child focused stress tasks designed to elicit anger, fear, and frustration were administered during early infancy, later infancy, and toddlerhood. Mothers’ and children’s saliva samples (later assayed for cortisol) were collected before and after the tasks. The strength of mother-child adrenocortical attunement was conserved across infancy and toddlerhood. The magnitude of maternal-child adrenocortical attunement decreased in response to the child-focused stress tasks. Maternal sensitivity and the child’s task-related emotional reactivity moderated adrenocortical attunement across the task, with greater maternal sensitivity during a free-play, and lower levels of child emotional reactivity during the stress tasks, stabilizing attunement from pre- to post-task levels. The findings advance our understanding of individual differences in the social regulation of adrenocortical activity in early childhood.
Abstract: The psychobiology of stress involves two major components, the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS). Research has revealed the association between behavior problems and the psychobiology of stress, yet findings are inconsistent and few studies have addressed the moderate correlations between behavior problems. This study examines the individual and interactive effects of HPA and ANS on child behavior problems while taking into account the comorbidity of externalizing and internalizing problems. Four saliva samples were collected from each participant in a community sample (N = 429; aged 11-12 years; 50.49 % male), which were assayed for cortisol (HPA) and alpha-amylase, sAA (ANS). Children’s behavior problems were assessed using parent-report and self-report versions of the Child Behavior Checklist. Latent variables were constructed to represent trait-like individual differences in cortisol and sAA. Low levels of HPA axis activity were associated with higher levels of both externalizing and internalizing problems, but only among children with low ANS arousal. The association between externalizing and internalizing problems diminished to non-significant after taking into account the influence of HPA axis activity and ANS arousal, which suggests that the psychobiology of stress explains a fair proportion of comorbidity of behavior problems. The findings support that interaction between HPA axis and ANS functioning has potential to clarify prior mixed findings and advance our understanding of the child behavior problems.