Patterns of cortisol reactivity in African-American neonates from low-income environments

A cluster-randomized trial of water, sanitation, handwashing and nutritional interventions on stress and epigenetic programming

A regulated stress response is essential for healthy child growth and development trajectories. We conducted a cluster-randomized trial in rural Bangladesh (funded by the Bill & Melinda Gates Foundation, ClinicalTrials.gov NCT01590095) to assess the effects of an integrated nutritional, water, sanitation, and handwashing intervention on child health. We previously reported on the primary outcomes of the trial, linear growth and caregiver-reported diarrhea. Here, we assessed additional prespecified outcomes: physiological stress response, oxidative stress, and DNA methylation (N = 759, ages 1-2 years). Eight neighboring pregnant women were grouped into a study cluster. Eight geographically adjacent clusters were block-randomized into the control or the combined nutrition, water, sanitation, and handwashing (N + WSH) intervention group (receiving nutritional counseling and lipid-based nutrient supplements, chlorinated drinking water, upgraded sanitation, and handwashing with soap). Participants and data collectors were not masked, but analyses were masked. There were 358 children (68 clusters) in the control group and 401 children (63 clusters) in the intervention group. We measured four F2-isoprostanes isomers (iPF(2α)-III; 2,3-dinor-iPF(2α)-III; iPF(2α)-VI; 8,12-iso-iPF(2α)-VI), salivary alpha-amylase and cortisol, and methylation of the glucocorticoid receptor (NR3C1) exon 1F promoter including the NGFI-A binding site. Compared with control, the N + WSH group had lower concentrations of F2-isoprostanes isomers (differences ranging from -0.16 to -0.19 log ng/mg of creatinine, P < 0.01), elevated post-stressor cortisol (0.24 log µg/dl; P < 0.01), higher cortisol residualized gain scores (0.06 µg/dl; P = 0.023), and decreased methylation of the NGFI-A binding site (-0.04; P = 0.037). The N + WSH intervention enhanced adaptive responses of the physiological stress system in early childhood.

Dehydroepiandrosterone at birth: Response to stress and relation to demographic, pregnancy and delivery factors

Enhanced production of dehydroepiandrosterone (DHEA) by the foetal hypothalamic-pituitary-adrenal (HPA) axis enables maturational events critical for labour induction and neonatal adaptation. Despite knowledge of the interconnected nature of maternal and foetal physiology and dramatic changes in DHEA production after birth, few studies have examined DHEA levels in newborns and none have examined DHEA's response to acute stress. Understanding normative patterns of early DHEA activity is needed to accurately assess functioning of the biological stress system with relevance for health and development. The present study analysed DHEA concentrations and change after stress among 93 newborns and associations with pregnancy, delivery and demographic risk factors. Three saliva samples, collected prior to and following a blood draw stressor, were used to determine baseline and stress reactive DHEA levels. Mothers self-reported on health behaviours during pregnancy. Data on obstetric factors were obtained from medical records. DHEA levels declined from pre- to post-stressor assessments. Results also showed that post-stressor DHEA change was significantly associated with administration of medications used to treat pain and accelerate labour. However, there was no significant variation in DHEA pre-stress levels or change after stress as a function of time after birth. By capturing DHEA levels after birth, the present study provides a window into prenatal health of the HPA system. The study also advances knowledge of DHEA in newborns by providing data on reference levels and important covariates. This information on basic adrenal physiology provides a foundation that can be expanded on to enhance understanding of early hypothalamic-pituitary-adrenal axis activity.

Basal and reactivity levels of cortisol in one-month-old infants born to overweight or obese mothers from an ethnically and racially diverse, low-income community sample

Establishing typical values of the steroid hormone cortisol at rest and after challenge is critical for understanding how environmental factors impact stress regulation and overall development, beginning at birth. Yet most extant samples are small or based upon low-risk populations, and few studies address the potential role of maternal weight during pregnancy in their study designs or sampling strategy. Here we report basal and reactivity levels of salivary cortisol within a racially and ethnically diverse sample of 132 infants approximately one month of age (Age in days: M=37.61, SD=7.27) born to lower income overweight or obese mothers. Reactivity was assessed in response to a multi-domain infant stressor paradigm, which included assessment via the Newborn Behavioral Observation (NBO) system and extensive anthropometric measurements. Sample means for basal, post stressors, and reactivity to the NBO were significantly lower than those reported in reviews of low-risk samples. Parity was associated with cortisol levels such that first-born infants had lower resting cortisol and higher reactivity than infants born to multiparous women. Latino infants had lower basal cortisol. No other demographic characteristics significantly predicted cortisol. The variability in cortisol levels present in this sample suggests that considerable psychophysiological diversity may exist in samples of low-SES or high-risk participants. Findings provide useful ranges for samples of racially and ethnically diverse newborns from low-income families.

Perceived Discrimination, Racial Identity, and Multisystem Stress Response to Social Evaluative Threat Among African American Men and Women

OBJECTIVE

Understanding individual differences in the psychobiology of the stress response is critical to grasping how psychosocial factors contribute to racial and ethnic health disparities. However, the ways in which environmentally sensitive biological systems coordinate in response to acute stress is not well understood. We used a social-evaluative stress task to investigate coordination among the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and immune/inflammatory system in a community sample of 85 healthy African American men and women.

METHODS

Six saliva samples, 2 at each of baseline, event, and recovery phases of the stressor task, were assayed for cortisol, dehydroepiandrosterone-sulfate, salivary alpha-amylase, and salivary C-reactive protein. Individual differences in perceived discrimination and racial identity were also measured.

RESULTS

Factor analysis demonstrated that stress systems were largely dissociated before stressor exposure but became aligned during event and recovery phases into functional biological stress responses (factor loadings ≥ .58). Coordinated responses were related to interactions of perceived discrimination and racial identity: when racial identity was strong, highly perceived discrimination was associated with low hypothalamic-pituitary-adrenal axis activity at baseline (B's = .68-.72, p < .001), low stress mobilization during the task (B's = .46-.62, p < .049), and a robust inflammatory response (salivary C-reactive protein) during recovery (B's = .72-.94, p < .002).

CONCLUSION

Culturally relevant social perceptions may be linked to a specific pattern of changing alignment in biological components of the stress response. Better understanding these links may significantly advance understanding of stress-related illnesses and disparities.

Parent training for children born premature: a pilot study examining the moderating role of emotion regulation

The aim of the current study was to examine the moderating effect of emotion regulation on treatment efficacy following a parent-training intervention, parent-child interaction therapy, for young children born preterm. In this pilot randomized controlled trial, 28 young children who were born preterm (i.e., <37 weeks gestation) and presented with elevated levels of externalizing behavior problems were randomly assigned to an immediate treatment or waitlist control group. Observers masked to treatment condition coded an index of emotion regulation (i.e., global regulation) during a videotaped 10-min parent-child interaction at the initial baseline assessment. Treatment efficacy was assessed using a parent-report questionnaire of child disruptive behavior. Results demonstrated that global regulation significantly interacted with treatment condition in predicting change in child disruptive behavior. Specifically, higher levels of distress at baseline were associated with greater improvements in child disruptive behavior following the intervention. These findings are discussed in the context of the differential susceptibility hypothesis and highlight the importance of considering children's emotion regulation skills in the course of psychosocial treatment for young children born premature.

Cortisol reactivity in young infants

In this systematic review on empirical studies of cortisol reactivity to acute stressors in infants, we specifically focus on the role of infant age in the early development of cortisol reactivity to stressors. Our findings indicate that many psychological stressors do not provoke a cortisol reaction, but in response to physical stressors, the infant HPA-axis mostly reacts with a moderate increase in post-stressor cortisol. Furthermore, for physical stressors only, cortisol reactivity effect sizes decrease with infant age, although relatively little is known for infants older than 6 months. These data provide more insight in the role of infant age in the development of cortisol reactivity in response to acute stressors. We discuss the role of caregivers in buffering the cortisol response to both psychological and physical stressors, and recommend extending the current knowledge on infant cortisol reactivity.

Cortisol response to physical activity in African American toddlers attending full-time day care

The purpose of this study was to examine African American toddlers' cortisol response to acute physical play activity within a full-time subsidized day care environment. Saliva samples were taken from participants (N = 22, ages 26-45.5 months) before and after physical play and control play conditions at the same time of day. Actiheart monitors were used to estimate the intensity of the play conditions. Although heart rate and other indicators were significantly higher during physical play, no change in cortisol levels was seen pre- to postphysical play. Further research is needed to better understand the cortisol response observed.

Stressor paradigms in developmental studies: what does and does not work to produce mean increases in salivary cortisol

The stress response system is comprised of an intricate interconnected network that includes the hypothalamic-pituitary-adrenocortical (HPA) axis. The HPA axis maintains the organism's capacity to respond to acute and prolonged stressors and is a focus of research on the sequelae of stress. Human studies of the HPA system have been facilitated enormously by the development of salivary assays which measure cortisol, the steroid end-product of the HPA axis. The use of salivary cortisol is prevalent in child development stress research. However, in order to measure children's acute cortisol reactivity to circumscribed stressors, researchers must put children in stressful situations which produce elevated levels of cortisol. Unfortunately, many studies on the cortisol stress response in children use paradigms that fail to produce mean elevations in cortisol. This paper reviews stressor paradigms used with infants, children, and adolescents to guide researchers in selecting effective stressor tasks. A number of different types of stressor paradigms were examined, including: public speaking, negative emotion, relationship disruption/threatening, novelty, handling, and mild pain paradigms. With development, marked changes are evident in the effectiveness of the same stressor paradigm to provoke elevations in cortisol. Several factors appear to be critical in determining whether a stressor paradigm is successful, including the availability of coping resources and the extent to which, in older children, the task threatens the social self. A consideration of these issues is needed to promote the implementation of more effective stressor paradigms in human developmental psychoendocrine research.

Maternal behavior predicts infant cortisol recovery from a mild everyday stressor

BACKGROUND

In the very first years of life, parenting is considered to be important for the regulation of the infant's emotional and physiological states. In the present study, three-month-old infants' cortisol responses (reactivity and recovery) to a mild everyday stressor, namely being taken out of the bath, were examined in relation to the quality of maternal behavior. It was hypothesized that a higher quality of maternal behavior towards the infant predicted lower cortisol reactivity as well as a better recovery from the reaction.

METHOD

The participants were 64 infants (34 boys and 30 girls) and their mothers. Maternal behavior (sensitivity and cooperation) towards the infant during the bathing routine was rated from videotapes. Salivary cortisol was obtained from the infants three times: before the bathing routine (T1), and 25 minutes (T2) and 40 minutes (T3) after the infants were taken out of the bath.

RESULTS

The infants reacted with a significant increase in cortisol to the stressor (from 6.8 nmol/l to 9.9 nmol/l), and regression analysis showed that the higher the quality of maternal behavior the better the cortisol recovery from the stressor.

CONCLUSION

Our findings indicate the potential importance of social processes for physiological recovery from everyday stressful situations in infants.

Parsing the relations between SES and stress reactivity: Examining individual differences in neonatal stress response

In an effort to further delineate the reported relations between socioeconomic status (SES) and stress reactivity in children, associations between three domains of perinatal risk: socio-demographic, obstetrical complications, and maternal psychological factors during the perinatal period, and cortisol and behavioral reactivity were examined in 100 healthy African American neonates whose families resided in low-income environments. Behavioral and cortisol response to a heel stick and the Neonatal Behavioral Assessment Scale (NBAS) was measured within the first 2 days of life. Significant associations were found between socio-demographic risk, obstetrical complications, and maternal psychological factors and neonatal behavior and cortisol in the context of the NBAS; few significant associations were found in the context of the heel stick. Greater magnitude of perinatal risk was associated with both higher and lower than average neonatal stress reactivity. The results provide preliminary data on the types of perinatal experiences that may have significant effects on stress reactivity in humans, especially in the context of families living in poverty. Application of these data to the hypothesis that prenatal stress results in programming of the fetal/neonatal stress response system is discussed.

Stress in pregnancy and infant HPA axis function: conceptual and methodological issues relating to the use of salivary cortisol as an outcome measure

Problems regulating behaviour and emotions in infancy may be a risk factor for the development of psychopathology later in life. Compelling evidence from animal models suggests that one potential pathway to early dysregulation is fetal programming of the hypothalamic-pituitary-adrenal (HPA) axis. According to this model, prenatal maternal stress and anxiety during sensitive periods of development can lead to enduring changes in fetal and offspring neurodevelopment and behaviour. While there is emerging evidence from human studies to suggest a link between maternal negative mood states in pregnancy and various cognitive, behavioural, and emotional disturbances in offspring, it is not yet clear whether the programming mechanism demonstrated in animal studies also applies to humans. Few studies have directly assessed HPA axis function in the infants of prenatally stressed women. Research in this area has been constrained by a number of measurement challenges unique to the assessment of cortisol in infants. This paper discusses these challenges with a view to stimulating further research in the area.

Association of hypothalamic-pituitary-adrenal axis function with neuropsychological performance in children with mild/moderate asthma

The present study examines the relationship between hypothalamic-pituitary-adrenal (HPA) axis function and child psychological/neuropsychological function in a group of children with mild to moderate asthma. The goal of the study was to determine whether child neuropsychological functioning and psychological functioning were associated with cortisol production in response to adrenocorticotropic hormone(ACTH) stimulation when assessed as area under the curve. Data for this study were gathered from 63 children who participated in an ancillary study within the Childhood Asthma Management Program (CAMP) during the pre-randomization phase of the CAMP trial. At 2 of the 8 CAMP clinical centers participants completed an ACTH stimulation test after an overnight stay in the General Clinical Research Center. Gender differences on baseline cortisol and change in cortisol 30 minutes after infusion of ACTH were present. Results further indicated significant associations between cortisol production and measures of child neuropsychological function. Stepwise multiple regression analysis revealed that cortisol change could be predicted by measures of gender, working memory, and arousal maintenance, providing support for the hypothesis that cortisol plays a modest role in the neuropsychological function of children with mild and moderate asthma. In contrast, cortisol production was not associated with child reports of psychological functioning. Limitations to the methods employed in this study are discussed.

Saliva sampling to assess cortisol levels in unrestrained common marmosets and the effect of behavioral stress

We report a method for taking saliva samples from unrestrained, captive marmosets (Callithrix jacchus) to assess levels of free cortisol. Saliva samples can be obtained reliably, without any habituation, by encouraging the marmosets to lick and chew a cotton-wool bud coated in banana. Saliva is thus left on the bud. We also tested sweetened fruit-drink crystals and a number of other substances, but none of these attracted all of the marmosets, and even flavors that were effective once soon lost their attraction. The presence of banana in the samples collected was found to lower the measured concentration of cortisol; however, as shown in samples taken with and without the banana coating on the bud, it did so in a linear and consistent way, and did not vary significantly among subjects. Therefore, a simple conversion factor could be applied to correct for the presence of banana. A first experiment showed that the marmosets exhibited a rise in salivary cortisol levels in response to social isolation. A second experiment showed elevation of cortisol during a period when the marmosets were disturbed by increased human activity and noise levels in the building in which they were housed. Hence, this method of saliva sampling is a convenient, noninvasive means of assessing cortisol levels in marmosets.

Examining stress reactivity in neonates: relations between cortisol and behavior

The association between cortisol and behavioral reactivity to a medical heel stick and a neurobehavioral exam was examined in 100 healthy African American neonates, who have been underrepresented in this area of research. Using continuous measures, behavioral distress was associated with cortisol reactivity to both stressors. High levels of behavioral distress, however, were associated with cortisol reactivity only in response to the neurobehavioral exam. In contrast, low levels of behavioral distress were associated with cortisol reactivity only in response to the heel stick. The results highlight potentially important parameters for exploring the relation between biological and behavioral reactivity to stress such as the operationalization of behavioral distress and the context in which a stress response is elicited.