This study examined the direct and interactive effects of stress reactivity and family adversity on socio-emotional and cognitive development in 338 five-to-six-year-old children. Neurobiological stress reactivity was measured as respiratory sinus arrhythmia and salivary cortisol responses to social, cognitive, sensory, and emotional challenges. Adaptation was assessed using child, parent, and teacher reports of externalizing symptoms, prosocial behaviors, school engagement, and academic competence. Results revealed significant interactions between reactivity and adversity. High stress reactivity was associated with more maladaptive outcomes in the context of high adversity but with better adaption in the context of low adversity. The findings corroborate a reconceptualization of stress reactivity as biological sensitivity to context by showing that high reactivity can both hinder and promote adaptive functioning.

The studies reported here examines stress-related psychobiological processes that might account for the high, disproportionate rates of dental caries, the most common chronic disease of childhood, among children growing up in low socioeconomic status (SES) families. In two 2004 -2006 studies of kindergarten children from varying socioeconomic backgrounds in the San Francisco Bay Area of California (Ns = 94 and 38), we performed detailed dental examinations to count decayed, missing or filled dental surfaces and microtomography to assess the thickness and density of microanatomic dental compartments in exfoliated, deciduous teeth (i.e., the shed, primary dentition). Crosssectional, multivariate associations were examined between these measures and SES-related risk factors, including household education, financial stressors, basal and reactive salivary cortisol secretion, and the number of oral cariogenic bacteria. We hypothesized that family stressors and stress-related changes in oral biology might explain, fully or in part, the known socioeconomic disparities in dental health. We found that nearly half of the five-year-old children studied had dental caries. Low SES, higher basal salivary cortisol secretion, and larger numbers of cariogenic bacteria were each significantly and independently associated with caries, and higher salivary cortisol reactivity was associated with thinner, softer enamel surfaces in exfoliated teeth. The highest rates of dental pathology were found among children with the combination of elevated salivary cortisol expression and high counts of cariogenic bacteria. The socioeconomic partitioning of childhood dental caries may thus involve social and psychobiological pathways through which lower SES is associated with higher numbers of cariogenic bacteria and higher levels of stress-associated salivary cortisol. This convergence of psychosocial, infectious and stress-related biological processes appears © 2010 Elsevier Ltd. All rights reserved.Corresponding Author: W. Thomas Boyce, University of British Columbia Vancouver, BC CANADA, tom.boyce@ubc.ca. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. to be implicated in the production of greater cariogenic bacterial growth and in the conferral of an increased physical vulnerability of the developing dentition. NIH Public Access KeywordsDental caries; socioeconomic status; stress; vulnerability; USA; children; psychobiological Dental caries is a preventable infectious disease in which bacterial fermentation of dietary carbohydrates in plaque reduces organic acids that erode the mineralized tiss...

Current methods of assessing children’s physiologic “stress reactivity” may be confounded by psychomotor activity, biasing estimates of the relation between reactivity and health. We examine the joint and independent contributions of psychomotor activity and challenge reactivity during a protocol for children ages 5–6 (N=338). Measures of parasympathetic (RSA) and sympathetic (PEP) reactivity were calculated for social, cognitive, sensory, and emotional challenge tasks. Reactivity was calculated relative to both resting and a paired comparison task that accounted for psychomotor activity effects during each challenge. Results indicated that comparison tasks themselves elicited RSA and PEP responses, and reactivity adjusted for psychomotor activity was incongruent with reactivity calculated using rest. Findings demonstrate the importance of accounting for confounding psychomotor activity effects on physiologic reactivity.

Objective To examine associations between autonomic nervous system and adrenocortical reactivity to laboratory stressors and buccal cell telomere length (BTL) in children. Methods The study sample comprised 78 five- and six-year-old children from a longitudinal cohort study of kindergarten social hierarchies, biological responses to adversity, and child health. Buccal cell samples and reactivity measures were collected in the spring of the kindergarten year. BTL was measured by realtime PCR, as the telomere-to-single copy gene (T/S) ratio. Parents provided demographic information; parents and teachers reported children’s internalizing and externalizing behavior problems. Components of children’s autonomic (heart rate (HR), respiratory sinus arrhythmia (RSA), pre-ejection period (PEP)) and adrenocortical (salivary cortisol) responses were monitored during standardized laboratory challenges. We examined relations between reactivity, internalizing and externalizing behavior, and BTL, adjusted for age, race, and gender. Results Heart rate and cortisol reactivity were inversely related to BTL, PEP was positively related to BTL, and RSA was unrelated. Internalizing behaviors were also inversely related to BTL (standardized β=−0.33, p=0.004). Split at the median of reactivity parameters, children with high sympathetic activation (decreasing PEP) and high parasympathetic withdrawal (decreasing RSA) did not differ with regard to BTL. However, children with both this profile and high cortisol reactivity (N=12) had significantly shorter BTL (0.80 vs. 1.00, χ2=7.6, p=0.006), compared with other children. Conclusions Autonomic and adrenocortical reactivity in combination were associated with shorter buccal cell telomere length in children. These data suggest that psychophysiological processes may influence, and that BTL may be a useful marker of, early biological aging.

Socioeconomic status (SES) is the single most potent determinant of health within human populations, from infancy through old age. Although the social stratification of health is nearly universal, there is persistent uncertainty regarding the dimensions of SES that effect such inequalities and thus little clarity about the principles of intervention by which inequalities might be abated. Guided by animal models of hierarchical organization and the health correlates of subordination, this prospective study examined the partitioning of children's adaptive behavioral development by their positions within kindergarten classroom hierarchies. A sample of 338 5-y-old children was recruited from 29 Berkeley, California public school classrooms. A naturalistic observational measure of social position, parent-reported family SES, and child-reported classroom climate were used in estimating multilevel, random-effects models of children's adaptive behavior at the end of the kindergarten year. Children occupying subordinate positions had significantly more maladaptive behavioral outcomes than their dominant peers. Further, interaction terms revealed that low family SES and female sex magnified, and teachers' child-centered pedagogical practices diminished, the adverse influences of social subordination. Taken together, results suggest that, even within early childhood groups, social stratification is associated with a partitioning of adaptive behavioral outcomes and that the character of larger societal and school structures in which such groups are nested can moderate rank-behavior associations.child development | social dominance | stress | mental health