Childcare as a stabilizing influence on HPA axis functioning: A reevaluation of maternal occupational patterns and familial relations

Early childhood stress responses to psychosocial stressors: The state of the science

The aim of this systematic review was to better understand whether and to what extent psychosocial stressors are associated with hypothalamic-pituitary-adrenal axis or autonomic nervous system stress responses in young children (1-6 years of age). Studies were classified by psychosocial stressors from the ecobiodevelopmental model: social and economic resources, maternal mental health, parent-child relationships, and the physical environment. Of the 2388 identified studies, 32 met full inclusion criteria, including over 9107 children. Child physiologic stress responses were measured as hair and urinary cortisol and cortisone, salivary diurnal and reactive cortisol, salivary reactive alpha-amylase, and respiratory sinus arrhythmia. There were 107 identified relations between psychosocial stressors and physiologic stress responses. Nearly two thirds of these relations suggested that children have dysregulated stress responses as either significantly blunted (n = 27) or increased (n = 37); 43 relations were not significant. Children most consistently had significantly dysregulated stress responses if they experienced postnatal maternal depression or anxiety. Some reasons for the mixed findings may be related to characteristics of the child (i.e., moderators) or stressor, how the stress response or psychosocial stressor was measured, unmeasured variables (e.g., caregiving buffering), researcher degrees of freedom, or publication bias.

Sociodemographics and chronic stress in mother-toddler dyads living in poverty

Experiencing chronic stress early in life is associated with later health disparities, and poverty may be a significant stressor for both mothers and children. With a sample of primarily Black and White mothers (N = 75) and toddlers (N = 71) living in poverty in the United States, we examined the direct relations between sociodemographic conditions of poverty and chronic physiological stress. Mothers completed questionnaires on sociodemographics, including mother/toddler race, mother's education, father's education, poverty level, economic hardship, marital status, unemployment status, and toddler sex. Physiological chronic stress was measured by assaying the cortisol content of 4 cm samples of hair cut from the posterior vertex of mothers and toddlers (20-24 months of age) to represent 4 months of stress. Mothers' and toddlers' chronic stress was significantly, moderately, and positively associated. Toddlers had a trending relationship of moderately higher chronic stress if they were Black compared to not Black. Mothers had significantly, moderately higher chronic stress if they were Black or had a Black toddler (compared to not Black), not married (compared to married), or were working (compared to not working). The findings suggest that these mothers, simultaneously navigating poverty and parenting a toddler, need resources to reduce chronic stress.

Promoting EF With Preschool Interventions: Lessons Learned From 15 Years of Conducting Large-Scale Studies

In the past two decades, a growing number of early childhood interventions that aim to improve school readiness have also targeted children's executive function (EF), building on the theory that promoting EF skills in preschool may play a key role in reducing the substantial gaps in school readiness and later achievement associated with family income. Despite the expansion of school readiness interventions across preschool, research evidence is mixed regarding what works to promote EF development and the impact of these interventions on children's EF skills, and subsequently, their academic and behavioral outcomes. This paper reviews four intervention approaches designed to support school readiness that may also improve children's EF skills by: (a) encouraging adaptive classroom behaviors, (b) improving social-emotional learning, (c) promoting play and direct training of EF skills, and (d) improving cognitive skills related to EF. We describe program effects from rigorous trials testing these approaches, including summarizing the takeaways from four large-scale intervention research studies conducted by the authors, involving over 5,000 children. We conclude by exploring open questions for the field and future directions for research and intervention program development and refinement.

Poverty, Caregiving, and HPA-Axis Activity in Early Childhood

The association between poverty and the activity of the hypothalamic pituitary adrenal (HPA) axis in early childhood is well established. Both ecological and transactional theories suggest that one way in which poverty may influence children's HPA-axis activity is through its effects on parents' behaviors, and over the past three decades a substantial literature has accumulated indicating that variations in these behaviors are associated with individual differences in young children's HPA-axis activity. More recent research suggests that non-parental caregiving behaviors are associated with HPA-axis activity in early childhood as well. Here we systematically review the literature on the association between both parental and non-parental caregiving behaviors in the context of poverty and the activity of the HPA-axis in early childhood. We conclude by noting commonalities across these two literatures and their implications for future research.

Biologic effects of stress and bonding in mother-infant pairs

OBJECTIVE

Maternal stress in humans influences behavior of children and can be assessed using biological markers. Mothers and their one-month-old infants were recruited from an existing study to examine baseline maternal serum oxytocin and hypothalamic-pituitary-adrenal axis response to infant blood heel stick stress as measured by salivary cortisol in the dyads. Objectives were to explore (1) relationships between mother and infant cortisol levels, (2) gender differences in infant biologic cortisol response, and (3) the association of cortisol levels in the dyads and maternal oxytocin levels

METHODS

Forty-two mother-infant dyads provided biologic samples and self-report data. Maternal oxytocin samples were obtained. Initial salivary cortisol was assessed in both the mother and infant, followed by a heel stick blood draw. Twenty minutes later, salivary cortisol was collected again from dyads.

RESULTS

Self-report measures were negative for depression and risk for childhood neglect. Although oxytocin and baseline cortisol in the infants was higher in mothers that did some breast-feeding, there was no statistically significant difference (p = 0.2 and p = 0.1, respectively). Analyses showed (a) higher baseline cortisol in mothers was related to higher baseline cortisol in infants (p ≤ 0.0001), (b) following the stressor, female infants had a larger positive change in cortisol, after adjusting for baseline cortisol (p = 0.045), and (c) there was no relationship between dyad cortisol levels and maternal oxytocin.

CONCLUSIONS

Maternal and infant biologic stress measures are related. Female infants have a larger hypothalamic-pituitary-adrenal response to a blood draw stressor as measured by salivary cortisol than male infants.

Chaos as a social determinant of child health: Reciprocal associations?

This study informs the social determinants of child health by exploring an understudied aspect of children's social contexts: chaos. Chaos has been conceptualized as crowded, noisy, disorganized, unpredictable settings for child development (Evans, Eckenrode, & Marcynyszyn, 2010). We measure chaos at two levels of children's ecological environment - the microsystem (household) and the mesosystem (work-family-child care nexus) - and at two points in early childhood (ages 3 and 5). Using data from the Fragile Families and Child Wellbeing Study (N = 3288), a study of predominantly low-income women and their partners in large US cities, we develop structural equation models that assess how maternal-rated child health (also assessed at ages 3 and 5) is associated with latent constructs of chaos, and whether there are important reciprocal effects. Autoregressive cross-lagged path analysis suggest that increasing chaos (at both the household and maternal work levels) is associated with worse child health, controlling for key confounders like household economic status, family structure, and maternal health status. Child health has little effect on chaos, providing further support for the hypothesis that chaos is an important social determinant of child health in this sample of relatively disadvantaged children. This suggests child health may be improved by supporting families in ways that reduce chaos in their home and work/family environments, and that as researchers move beyond SES, race, and family structure to explore other sources of health inequalities, chaos and its proximate determinants may be a promising avenue for future research.

Factors associated with cortisol levels and health in 5-6-year-old children

OBJECTIVES

This study assesses the relationships between social context (family and inter-peer context), stress, and illness in 5-6-year-old children.

METHODS

To this end, data were collected on spontaneous social interpeer behavior; families provided data on stress, anxiety, and parental acceptance-rejection; and the children's pediatricians provided data relative to their health. Data on stress-related hormones (cortisol) were collected using saliva samples.

RESULTS

The results revealed that none of the variables examined were significantly related to illness development in the subjects in the sample group. Cortisol levels, however, were positively associated with a record of chronic or congenital illnesses, the manifestation of behaviors related to the search for leadership status in the group and the presence of stressful events in the family environment.

CONCLUSIONS

Despite finding no relationship between children's level of adrenocortical activity and the contracting or contingent development of diseases, we did find that chronic/congenital diseases may constitute a source of early stress in childhood. Certain conditions of uncertainty in the social context (family and interpeer) also seem to constitute different sources of stress.

Hypothalamic-pituitary-adrenal axis activity and upper respiratory tract infection in young children transitioning to primary school

RATIONALE

We have previously reported an increase in salivary cortisol in a cohort of 4-year-old children transitioning to primary school. We hypothesised that increased cortisol in response to this acute naturalistic stress in early development may be immunostimulatory and associated with positive health outcomes.

OBJECTIVES

We tested this hypothesis by measuring upper respiratory tract infection (URI) across the first 6 months of school, in relation to salivary cortisol at the end of the second week following school transition

METHODS

Seventy children supplied morning and evening saliva samples for cortisol assay. Children were psychologically assessed for temperament and behavioural adaptation. Symptoms of URI were recorded in diary form, and variables relating to URI occurrence, duration and severity were assessed.

RESULTS

Children with higher evening cortisol at school transition experienced significantly fewer episodes of URI over the following 6 months. Diurnal cortisol change was negatively correlated with number of illnesses across the 6 months, indicating an association between a greater decline in cortisol across the day and a greater number of colds. URI severity was associated with the greatest resistance to URI infection in children who were less socially isolated and who had a smaller diurnal change in cortisol across the day.

CONCLUSIONS

Our results showing that higher cortisol is associated with lower URI may be explained by proposing that increased cortisol in response to the naturalistic stress of school transition may prime the immune system to develop resistance to URI at this critical stage of a child's development.

Diurnal cortisol secretion at home and in child care: a prospective study of 2-year-old toddlers

BACKGROUND

Previous studies indicate that children may experience disrupted cortisol secretion in child care. The extent to which this is a transient or long-term disruption is not known, as most studies have relied on cross-sectional designs, and age-heterogeneous small sample sizes. This study aims to (a) compare cortisol secretion measured at home and in child care at 2 and 3 years of age, (b) investigate cortisol changes from 2 to 3 years of age, (c) examine whether age at initiation of child care is associated with cortisol secretion, and (d) investigate whether cortisol secretion in child care is linked to behavioural problems.

METHODS

Saliva samples were collected in a cohort of children recruited at 2 years of age from a larger population sample composed of women seen for the first time during pregnancy. Saliva was sampled twice a day (morning and afternoon) over two consecutive days at home and in child care at 2 (n = 155) and 3 years of age (n = 116). Interviews regarding the familial socioeconomic background and child care history were conducted with the mothers.

RESULTS

At 2 years of age, children showed a flat diurnal cortisol pattern in child care and a decreasing pattern at home. At age 3 years, children showed decreasing patterns both at home and in child care. Also at 3 years, children with less child care experience (i.e., entry after 16 months) had higher cortisol levels in child care and lower levels at home. In contrast, those with more experience (i.e., entry prior to 8 months) had lower cortisol in child care and higher cortisol at home.

CONCLUSION

The different patterns of diurnal secretion observed in child care as compared to home is transient for most children, diminishing as they get older, whereas home and child care overall levels later on may be influenced by the cumulated experience with child care.

Absence of a normal cortisol awakening response (CAR) in adolescent males with Asperger syndrome (AS)

In addition to abnormalities in social and communication development, a 'need for sameness' and 'resistance to change' are features of autistic spectrum disorders first identified by Kanner in 1943. Our ability to react to change is modulated by the hypothalamic-pituitary-adrenal (HPA) axis, a feature of which is a dramatic increase in cortisol upon waking, the Cortisol Awakening Response (CAR). This study examined whether the CAR was evident in 20 adolescent males with Asperger Syndrome (AS) and 18 age-matched typically developing (TD) controls (aged 11-16). Whilst a significant CAR was evidenced in the TD control group, this was not the case for those with AS. A normal diurnal decrease in cortisol, however, was evident in both groups. The implication that individuals with AS may have an impaired response to change in their environment due to a refractory HPA axis is discussed.

Use of the dexamethasone-corticotrophin releasing hormone test to assess hypothalamic-pituitary-adrenal axis function in rheumatoid arthritis

Objectives. Hypothalamic-Pituitary-Adrenal axis function may be abnormal in rheumatoid arthritis (RA). A pilot study in 7 patients suggested impaired glucocorticoid feedback in some patients after the dexamethasone-corticotrophin releasing hormone (CRH) test. This study aimed to investigate the dexamethasone-corticotrophin releasing factor test in a larger group of patients and relate the results to characteristics of the disease. Methods. Outpatients with active RA (>/=3 swollen and tender joints and C-reactive protein > 10 mg/L) took dexamethasone (1.5 mg) at 23:00 hour in the evening. Next day, baseline saliva and plasma samples were collected, CRH was infused at 11:00 hour, and 4 serial blood and saliva samples were collected. Plasma samples were stored at -80 degrees C and a radioimmunoassay performed for saliva and plasma cortisol. Results. All 20 participants showed normal dexamethasone suppression and mounted no response to the CRH challenge. In samples with measurable cortisol, there was a strong correlation between saliva and plasma values (r = 0.876, n = 26, P < .01). Conclusion. No abnormalities were found in the Dexamethasone-CRH test in RA patients in contrast to a previous pilot study. Salivary cortisol measurement may offer an alternative noninvasive technique to plasma cortisol in RA patients in future studies.

Measurement and meaning of salivary cortisol: a focus on health and disease in children

Measurement of salivary cortisol can provide important information about hypothalamic-pituitary-adrenal (HPA) axis activity under normal conditions and in response to stress. However, there are many variables relating to the measurement of cortisol in saliva which may introduce error and therefore may render difficult the comparison and interpretation of data between, and within, laboratories. This review addresses the effects of gender, age, time and location of sampling, units of measurement, assay conditions and compliance with the protocol, all of which have the potential to impact upon the precision, accuracy and reliability of salivary cortisol measurements in the literature. Some of these factors are applicable to both adults and children, but the measurement of salivary cortisol in children introduces aspects of unique variability which demand special attention. The specific focus of this review is upon the somewhat neglected area of methodological variability of salivary cortisol measurement in children. In addition to these methodological issues, the review highlights the use of salivary cortisol measurements to provide information about HPA axis dysfunction associated with psycho- and patho-physiological conditions in children. Novel applications for salivary cortisol measurements in future research into HPA axis activity in children are also discussed.

The influence of parent–infant cosleeping, nursing, and childcare on cortisol and SIgA immunity in a sample of british children

Substantial variation in childcare arrangements exists both within and between populations. Research has suggested negative stress-related outcomes for children who regularly attend daycare facilities. In the present study, 122 cortisol and 94 secretory immunoglobulin A (SIgA) samples from 32 British children aged between 3 and 8 were analyzed using multilevel modeling to assess effects of daycare attendance and other childcare-related variables on children's stress and SIgA immune function. Parents' reports of children's aggression and family discord within 2 hr of saliva collection were associated with elevated cortisol levels in children. With these acute stressors statistically controlled, retrospective data on parent-child cosleeping showed that children who had coslept in their parent(s) room had lower cortisol levels, as did children who had attended less daycare in the first 4 years of life. The parenting-related variables did not predict SIgA immunity. The results are discussed in the context of theories of parenting strategies.