Stress reactivity in 15-month-old infants: Links with infant temperament, cognitive competence, and attachment security

Behavioral inhibition, negative parenting, and social withdrawal: Longitudinal associations with loneliness during early, middle, and late adolescence

Adolescent loneliness can have detrimental effects on physical and mental health, but there is limited understanding of its antecedents in infancy and childhood. A 20-year longitudinal, multi-informant, and multi-methods study (first data collection in 1998) was conducted to examine mechanisms underlying adolescent loneliness (N = 128, 52% boys, M_{age_baseline}  = 1.23, SD = 0.02, 99% White, recruitment in Dutch urban, healthcare centers). Structural equation modeling showed that high infant behavioral inhibition (BI) was indirectly associated with high loneliness during adolescence via high childhood social withdrawal. This indirect effect was equally strong during early, middle, and late adolescence. Contrary to expectations, infant parenting did not moderate the relation between BI and social withdrawal. The results suggest a developmental cascade with infant BI showing long-lasting indirect effects on adolescent loneliness up to 20 years later via childhood social withdrawal.

Examining attachment, cortisol secretion, and cognitive neurodevelopment in preschoolers and its predictive value for telomere length at age seven

Background

Secure attachment reflects caregiver-child relationship in which the caregiver is responsive when support and comforting are needed by the child. This pattern of bond has an important buffering role in the response to stress by the reduction of the negative experience and its associated physiological response. Disruption of the physiological stress system is thought to be a central mechanism by which early care impacts children. Early life stress causes cellular and molecular changes in brain regions associated with cognitive functions that are fundamental for early learning.

Methods

The association between attachment, cortisol response before and after the Strange Situation Experiment, and neurodevelopment was examined in a sample of 107 preschoolers at age three. Also, the predictive effect of cortisol reactivity and attachment on telomere length at age seven was investigated in a followed-up sample of 77 children.

Results

Children with insecure attachment had higher cortisol secretion and poorer neurodevelopmental skills at age three. A significant cortisol change was observed across the experiment with non-significant interaction with attachment. The attachment and neurodevelopment association was not mediated by cortisol secretion. Preschoolers' attachment and cortisol did not associate nor interacted to predict telomere length at age seven.

Conclusion

These findings add evidence to the detrimental effects of insecure attachment as an aggravator of the physiological response to stress and poorer neurodevelopment during the preschool period. Although attachment and cortisol were not predictive of telomere length, intervention policies that promote secure attachment are more likely to positively echo on several health domains.

Behavioral inhibition as an early life predictor of callous-unemotional traits

Callous-unemotional (CU) traits predict behavioral problems in adolescence. But little is known about early modulatory factors. Behavioral Inhibition (BI) in particular has been suggested to protect against the development of CU-traits. This temperamental predisposition is characterized by heightened environmental sensitivity. The current prospective longitudinal study examined whether BI at 15 months of age predicted lower CU-traits across development to age 21. A longitudinal sample of normatively developing children ( n = 125) was used. BI was assessed at 15 months using a standard stranger/robot paradigm. CU-traits were assessed at 2, 5, 9, 12, 14, 17, and 21 years with parent, teacher, and self-reports. Developmental pathways across all available data points were examined using Bayesian mixed models and k-means cluster analysis. Infant BI predicted lower CU-traits across development for girls, suggesting that BI buffers the long-term development of CU-traits for girls. CU-traits peaked in early adulthood. Boys scored higher and showed higher increases in CU-traits than girls from childhood onward. There was no gender difference regarding infant BI. Together, the findings demonstrated gender differences in the development of CU-traits, with a protective role of BI for girls. These results shed new light on the developmental trajectories and protective factors of CU-traits and provide starting points for interventions aiming at increasing children’s responsiveness to external cues to prevent antisocial traits and conduct problems.

Parent-Infant Attachment Insecurity and Emotional Eating in Adolescence: Mediation through Emotion Suppression and Alexithymia

Emotional eating (EE), the propensity to eat in response to emotions, is thought to have its origins in the early parent–infant relationship. This study tested the hypothesis that infant attachment insecurity results in EE in adolescence through the increased use of the emotion regulation strategy suppression of emotions and subsequent alexithymia. At the age of 15 months, parent–infant attachment security (n = 129) was observed with two abbreviated attachment measures: the shortened strange situation procedure (SSSP), and the shortened attachment Q-set (S-AQS). At the age of 12 years, children completed self-report questionnaires to assess the suppression of emotions, alexithymia, and EE. At the age of 16 years, EE was measured again. The mediation models indicated that lower parent–infant attachment security predicted increased use of suppression of emotions, which was related to increased alexithymia, and in turn more EE at the age of 12 years. These results were similar and significant for both attachment measures, and also (marginal) significant with EE at the age of 16 years as an outcome. Lastly, when parental caregiving quality was included, the models with the SSSP as predictor remained significant, but the models with the S-AQS became insignificant. These results indicated that to a certain extent, infant attachment security could predict adolescent EE above and beyond parental caregiving quality.

Adrenocortical interdependence in father-infant and mother-infant dyads: Attunement or something more?

Father-infant and mother-infant (one-year-olds) adrenocortical attunement was explored during the Strange Situation Procedure (SSP) among 125 father-infant and 141 mother-infant dyads. Cortisol was assessed at baseline (T1), 20 (T2), and 40 minutes (T3) after the first parent-infant separation. Initial correlations indicated significant associations between father-infant and mother-infant cortisol at each time. Cortisol interdependence was further explored using Actor-Partner Interdependence Models. There was no evidence supporting cortisol interdependence based on within-time residual correlations between parent-infant cortisol, once stability and cross-lagged paths were controlled. Infant cortisol at T2 predicted T3 cortisol for fathers and mothers resulting in a series of follow-up exploratory analyses to examine mediating processes which revealed that infant distress during the SSP predicted infant T2 cortisol, which, in turn, predicted infant negativity during the 15-min mother-infant teaching task that followed the SSP. Among father-infant dyads, infant T2 cortisol predicted infant negativity during father-infant interaction, with infants expressing more negativity having less sensitive fathers. Findings provide little support of parent-infant adrenocortical attunement across either father-infant or mother-infant dyads during the SSP, but preliminary evidence indicates infant distress as a potential mediator. Future research may want to focus on affective and behavioral processes that underlie the concept of parent-infant adrenocortical attunement.

Examining the role of socioeconomic status and temperament in the hair cortisol levels of infants

Socioeconomic status (SES) appears to be an important contextual factor in children's developmental outcomes, including their responses to stress. However, some children are more susceptible to its effects than others. Hair cortisol is a newer method of assessing the activity of the HPA axis, providing cumulative cortisol levels. The present article examined whether temperament (negative emotionality) moderates the association between an SES index and the hair cortisol concentration (HCC) of infants. Sixty infants from 6 to 15 months of age were recruited, of which 49 had sufficient hair for cortisol analysis. The SES index was calculated from the education levels of the mothers, family income, and a scale measuring the quality of the home environment. Negative emotionality was measured with the three sub-scales of the Infant Behavior Questionnaire (falling reactivity, distress to limitations, and fear). Among infants low in negative emotionality, there was no association between SES and cortisol. In contrast, among those high in negative emotionality, a significant association was obtained. These infants showed lower levels of HCC in lower-SES environments. The findings suggest that there are individual differences in reacting to the environment, and low levels of cortisol (not high) were found in susceptible infants in lower-SES families.

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.

Daily parent-adolescent cortisol associations: Unpacking the direction of effects

Prior studies suggest bidirectional relationships between parent and adolescent behavior. This study examined how parents and their adolescent child's cortisol patterns are associated across days and if there are bidirectional associations between parent and child cortisol. Participants included two samples of employees and their children who participated in a daily diary study where diurnal salivary cortisol was collected on four study days (N = 318 dyads, Myouth age = 13.18 years, 52 % female). Autoregressive cross-lagged models were used to estimate parent-driven effects (parent cortisol effects on adolescent cortisol) and adolescent-driven effects (adolescent cortisol effects on parent cortisol). Adolescents' steeper cortisol awakening response (CAR) was significantly associated with parents' steeper CAR the following day. Adolescents' higher bedtime cortisol levels were also significantly associated with parents' higher bedtime cortisol levels the following day. Parents' cortisol did not predict their children's next-day cortisol. Results support a primarily adolescent-driven process of stress transmission in families. These results suggest that interventions to reduce adolescent stress, as well as to reduce parents' reactivity to adolescents, may be warranted.

Salivary cortisol reactivity to psychological stressors in infancy: A meta-analysis

Measurement of salivary cortisol is a practical and non-invasive tool for studying stress reactivity to various types of stressors even in young infants. Whereas studies using physical stressors during the first months of life have found robust cortisol responses to painful stimuli, research with older infants using psychological stressors (e.g., parental separation) has produced mixed findings, limiting our understanding of potential developmental changes in cortisol reactivity across infancy. In the present study, we used meta-analysis to systematically investigate whether psychological stressor paradigms are associated with measurable cortisol responses in infants under 18 months of age and whether the magnitude of the responses is moderated by the type of psychological stressor (i.e., separation, frustration, novelty, or disruption of parental interaction), infant age, and other potential moderators. Across 47 studies (N = 4095, age range: 3-18 months), we found that commonly used psychological stressor paradigms are associated with a small (Hedges' g = .11) increase in salivary cortisol levels in typically developing infants. Stressor type moderated the effect sizes, and when effect sizes in each category were analyzed separately, only the separation studies were associated with a consistent increase in cortisol following the stressor. Age did not moderate the effect sizes either in the full set of studies or within the separate stressor types. These meta-analytic results indicate that the normative cortisol response to psychological stressors across infancy is small and emphasize the need for standardized stressor paradigms to assess cortisol responses systematically across infancy.

The relationships among MAOA, COMT Val158Met, and 5-HTTLPR polymorphisms, newborn stress reactivity, and infant temperament

INTRODUCTION

Variance in hypothalamic-pituitary-adrenal (HPA) axis reactivity is considered to be one of the sources of differences in infant temperament. The cortisol enters into interactions with dopamine and serotonin, so it is expected that polymorphisms in genes coding monoamine metabolism influence both HPA axis reactivity and temperament.

METHODS

We therefore explore the relationship among 5-HTTLPR S/L, MAOA H/L, and COMT Val158Met polymorphisms, the stress reaction of newborn infants after a heel stick blood draw (measured by determining salivary cortisol at three time points), and temperament assessed at the age of 3 months using Rothbart's Infant Behavior Questionnaire-Revised (IBQ-R) with a sample of 84 infants.

RESULTS

The decrease in the salivary cortisol correlated with nine primary scales and all three secondary scales of IBQ-R. Children with a greater cortisol decrease were assessed as less susceptible to negative emotions, more extraverted, and more regulated. The polymorphisms that were observed were related both to the course of the stress reaction and to temperament. The 5-HTTLPR S allele was connected to higher scores for Negative Emotionality and lower scores for Orienting/Regulatory Capacity. The presence of the MAOA L allele predisposed its carriers to higher scores for Negative Emotionality, lower scores for Orienting/Regulatory Capacity, and a lower decrease in cortisol. The Met allele of COMT Val158Met polymorphism was connected to a higher Positive Affectivity/Surgency and Orienting/Regulatory Capacity and a greater cortisol decrease.

CONCLUSIONS

Contrary to previous studies referring mainly basal cortisol and its increase, the results of our study emphasize the importance of cortisol elimination in infant temperament. Another interesting finding was a higher cortisol increase, higher Distress to Limitations, Negative Emotionality, and Approach in MAOA LL homozygotes which are traditionally understood as more vulnerable toward early stress in developing later externalizing behavior.

Emotional Stress During Pregnancy - Associations With Maternal Anxiety Disorders, Infant Cortisol Reactivity, and Mother-Child Interaction at Pre-school Age

There is growing evidence that even milder forms of maternal stress or anxiety during pregnancy affect the fetus causing possible long-term consequences for infant and child development. The mechanisms through which prenatal maternal stress may affect the unborn are not yet entirely clarified. Due to limited self-regulatory skills after birth, infants depend on sensitive behavior of their parents to regulate affective states and physiological arousal. Dyadic affect regulation has been linked to various developmental patterns up to adolescence and thereby represents a key element of early social relationships. Aim of the study was to evaluate possible long-term consequences of emotional stress during pregnancy and postpartum anxiety disorders, as well as infant postpartum cortisol reactivity on mother–child-interaction at pre-school age. The sample comprised of N = 63 mother–infant dyads at study entry, n = 28 diagnosed with postpartum anxiety disorders according to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), n = 35 were healthy controls. Mothers were interviewed with the Structured Clinical Interview for DSM-IV Disorders at an average infant age of M = 4.1 months and filled out a questionnaire regarding emotional stress during pregnancy. Further, they were videotaped during the Face-to-Face-Still-Face paradigm (FFSF), a widely used mild socio-emotional stressor for infants. To determine infant stress-reactivity, infant salivary cortisol was collected before, immediately after and 20 min after the FFSF. Missing values were estimated by multiple imputations. At the age of M = 5.3 years, mother-child-interaction was re-assessed in a follow-up sample of n = 30 dyads via a free-play situation. Moreover, dimensional measures for anxiety were assessed. Mothers in the clinical group reported significantly higher stress scores than the control group. Infant stress reactivity in the early postpartum period and maternal anxiety symptoms at the 5-year follow-up assessment were significantly associated with dyadic interaction quality at pre-school age. Even though maternal stress during pregnancy did not directly predict mother–child interaction quality at pre-school age, it was significantly correlated with infant cortisol reactivity during postpartum period. Nevertheless, caution should be taken when interpreting the results considering the small sample size.

The development of the cortisol response to dyadic stressors in Black and White infants

Acute reactivity of the stress hormone cortisol is reflective of early adversity and stress exposure, with some studies finding that the impact of adversity on the stress response differs by race. The objectives of the current study were to characterize cortisol reactivity to two dyadically based stress paradigms across the first year of life, to examine cortisol reactivity within Black and White infants, and to assess the impact of correlates of racial inequity including socioeconomic status, experiences of discrimination, and urban life stressors, as well as the buffering by racial socialization on cortisol patterns. Salivary cortisol reactivity was assessed at 4 months of age during the Still Face paradigm (N = 207) and at 12 months of age across the Strange Situation procedure (N = 129). Infants demonstrated the steepest recovery after the Still Face paradigm and steepest reactivity to the Strange Situation procedure. Race differences in cortisol were not present at 4 months but emerged at 12 months of age, with Black infants having higher cortisol. Experiences of discrimination contributed to cortisol differences within Black infants, suggesting that racial discrimination is already "under the skin" by 1 year of age. These findings suggest that race-related differences in hypothalamic-pituitary-adrenal reactivity are present in infancy, and that the first year of life is a crucial time period during which interventions and prevention efforts for maternal-infant dyads are most likely able to shape hypothalamic-pituitary-adrenal reactivity thereby mitigating health disparities early across the life course.

Age-Adapted Stress Task in Preschoolers Does not Lead to Uniform Stress Responses

Acute stress response measures serve as an indicator of physiological functioning, but have previously led to contradictory results in young children due to age-related cortisol hypo-responsivity and methodological inconsistencies in assessment. The aim of this study was to investigate stress responses during a validated age-adapted socio-evaluative stress task in children aged 2-6 years in a child care environment and to detect socio-demographic, task- and child-related characteristics of stress responses. Stress responses were assessed in 323 children for salivary cortisol and salivary alpha amylase (sAA), and in 328 children for changes in heart rate variability (HRV). These data were then associated with socio-demographic (e.g. SES), task-related (e.g. task length) and child-related characteristics (e.g. self-regulation) of stress responses using multilevel models. Analyses revealed elevated sympathetic reactivity (sAA: Coeff=0.053, p=0.004) and reduced HRV (Coeff=-0.465, p<0.001), but no hypothalamic-pituitary-adrenal (HPA) response (Coeff=0.017, p=0.08) during the stress task. Child's age (Coeff=-5.82, p<0.001) and movement during the task (Coeff=-0.17, p=0.015) were associated with acute cortisol release, while diurnal sAA was associated with acute sAA release (Coeff=0.24, p<0.001). Age (Coeff=-0.15, p=0.006) and duration of the task (Coeff=0.13, p=0.015) were further associated with change of HRV under acute stress condition. Children showed inconsistent stress responses which contradicts the assumption of a parallel activation of both stress systems in a valid stress task for young children and might be explained by a pre-arousal to the task of young children in a child care setting. Further results confirm that child- and task-related conditions need to be considered when assessing stress responses in these young children.

Prenatal intimate partner violence exposure predicts infant biobehavioral regulation: Moderation by the brain-derived neurotrophic factor (BDNF) gene

The ability to regulate stress is a critical developmental milestone of early childhood that involves a set of interconnected behavioral and physiological processes and is influenced by genetic and environmental stimuli. Prenatal exposure to traumatic stress and trauma, including intimate partner violence (IPV), increases risk for offspring biobehavioral regulation problems during childhood and adolescence. Although individual differences in susceptibility to prenatal stress have been largely unexplored, a handful of studies suggest children with specific genetic characteristics are most vulnerable to prenatal stress. We evaluated the brain-derived neurotrophic factor Val66Met gene (BDNF) as a moderator of the effect of prenatal IPV exposure on infant temperamental and cortisol regulation in response to a psychosocial challenge. Ninety-nine mother–infant dyads recruited from the community were assessed when infants (51% female) were 11 to 14 months. Maternal reports of IPV during pregnancy and infant temperament were obtained, and infant saliva was collected for genotyping and to assess cortisol reactivity (before and after the Strange Situation Task). Significant genetic moderation effects were found. Among infants with the BDNF Met allele, prenatal IPV predicted worse temperamental regulation and mobilization of the cortisol response, while controlling for infant postnatal exposure to IPV, other maternal traumatic experiences, and infant sex. However, prenatal IPV exposure was not associated with temperamental or cortisol outcomes among infant carriers of the Val/Val genotype. Findings are discussed in relation to prenatal programming and biological susceptibility to stress.

The Interplay Between Early Father Involvement and Neonatal Medical Risk in the Prediction of Infant Neurodevelopment

The current study examines the association between early father involvement and infant neurodevelopment, and whether neonatal medical risk moderates this association. Data from approximately 6000 fathers and their children were obtained from the Early Childhood Longitudinal Study: Birth Cohort (ECLS-B). Hierarchical regression was employed to analyze the data. The findings reveal that the association between early father involvement and infant neurodevelopment is contingent on both the timing of involvement (i.e., prenatal/perinatal or infancy) and offspring medical status at birth. The neurodevelopment of medically at-risk neonates was enhanced when fathers were involved during the gestational period and at the time of their birth. This relationship was not detected, however, in the case of infants who did not experience medical risks as neonates. Neonatal medical risk appears to be an important moderating factor in the link between father involvement during pregnancy and childbirth and infant neurodevelopment. Practitioners should continue to make efforts to involve fathers during gestation and childbirth. The findings of the present study suggest that doing so may protect against neurodevelopmental delays in neonates with medical risks.

Maternal Distraction During Breast- and Bottle Feeding Among WIC and non-WIC Mothers

OBJECTIVE

To explore the prevalence and correlates of maternal distraction during infant feeding within a sample of mothers enrolled or not in the Special Supplemental Nutrition Program for Woman, Infants, and Children (WIC).

DESIGN

Mothers kept diaries of their infants' feeding patterns.

PARTICIPANTS

Mothers (n = 75) with infants aged ≤6 months.

MAIN OUTCOME MEASURES

Within the diaries, mothers recorded what else, if anything, they did during the feeding. Mothers also completed questionnaires on demographics, feeding styles, and infant temperament and eating behaviors.

ANALYSIS

Mothers' responses were coded into thematic categories. Feedings were classified as distracted when the mothers reported doing something other than feeding and/or interacting with the infant. Logistic regression was used to explore whether mothers exhibited different levels of distraction when breastfeeding (BF) vs bottle feeding. The researchers used multiple stepwise regression to explore associations between distracted feeding and characteristics of mothers and infants.

RESULTS

Distractions were reported during 43% of feedings; 26% involved technological distractors. Mothers who were multiparous and perceived that their infants had greater appetites reported greater levels of any distraction during feeding. Mothers who were of racial/ethnic minorities, adhered to laissez faire feeding style, had younger infants, and perceived their infants to have lower food responsiveness and greater appetite reported greater levels of technological distraction. Being enrolled in WIC was not associated with mothers' levels of distracted feeding.

CONCLUSIONS AND IMPLICATIONS

Mothers reported a wide variety of distractions during both BF and bottle feeding; higher levels of distraction were associated with characteristics of both mothers and infants. Further research is needed to understand whether and how maternal distraction affects feeding outcomes. Awareness of such distractions and their potential impact would be useful to practitioners working with pregnant and postpartum women.

Fifteen-month-old infants' cortisol levels decrease after a 30-min-warm-up procedure

Stress-induction procedures designed to increase cortisol levels in infants have been ineffective in many studies. One reason might be that infants did not have sufficient time to settle into the laboratory environment prior to the start of the stress induction, and thus already had high baseline levels of cortisol. In this study we investigate whether an extended warm-up period reduces infants' (N=22) cortisol levels. Fifteen-month-old infants' saliva cortisol was measured upon arrival at the laboratory. Then, they were allowed to play with their parent. After 30min, cortisol was measured again. There was a decrease in cortisol after 30min of free play. Our study suggests that infants' cortisol levels decrease when infants have the opportunity to acclimatize to the test environment. An extended warm-up phase prior to stress induction procedures might be necessary to reliably increase cortisol levels in infants.

Salivary cortisol and cognitive development in infants from low-income communities

Early stress exposure is proposed to have significant lasting effects on cognitive development. The glucocorticoid hormone cortisol, a product of the hypothalamic-pituitary-adrenal (HPA) axis, is a particular focus of research, however, the majority of past research has been based on studies of older children and adults. Evidence linking cortisol levels in infancy with cognitive development is lacking. In a large cohort sample of infants (N = 1091) oversampled for psychosocial risk, we tested whether basal cortisol levels and cortisol reactivity to emotional stressors administered at 7 and 15 months of age were associated with cognitive development measured at 15 months. Cognitive development was measured using the Mental Development Index of the Bayley Scales of Infant Development. Multiple regression analyses indicated that basal cortisol levels at 15 months, and to a lesser extent at seven months, were inversely associated with infant cognitive development after adjusting for psychosocial and obstetric risk. The findings provide some of the first evidence that HPA axis activity in infancy is associated with early cognitive development.

Cortisol levels of infants in center care across the first year of life: links with quality of care and infant temperament

Cortisol concentrations of older children in childcare centers have been found to be higher than at home. This study focuses on infant cortisol in childcare centers throughout the first year of life, and aims to investigate whether inter-individual differences can be explained by temperament, the quality of maternal behavior, and the quality of center care. Sixty-four infants were followed for 9 months after entering care at 3 months of age. Salivary samples were taken at 10.00 h and 16.00 h in center care (in post-entry weeks 1, 2, 3, 4, 8, 12, 16, 24, and 36) and at home (in post-entry weeks 1, 24, and 36). Prior to entry, mothers completed a temperament questionnaire and the quality of maternal behavior (sensitivity and cooperation) was observed during routine bathing sessions. Subsequently, the infants were visited three times at center care to observe the quality of infant's interactive experiences with their professional caregiver. Longitudinal regression models showed that both morning and afternoon cortisol were higher in center care compared to home. Longitudinal regression models showed that infants receiving higher quality of maternal behavior displayed higher morning cortisol in center care, compared to infants receiving lower quality of maternal behavior. Higher quality of maternal behavior was also related to higher afternoon cortisol in center care, but only in infants high in negative emotionality. Center care quality was not related to cortisol. In sum, young infants show higher cortisol concentrations in center care that are related to infant temperament and quality of maternal behavior at home.

Stress impairs cognitive flexibility in infants

In human adults, learning and memory under acute stress are characterized by an increased use of rigid habitual response strategies at the cost of flexible cognitive strategies. The immediate effects of stress on cognitive functioning early in life are not well understood. Here we show experimentally that acute stress leads human infants to perform habitual behavior rigidly. We found that 15-mo-old infants exposed to stress thereafter kept performing a previously effective action, even after the action suddenly became ineffective. Infants in a no-stress control group flexibly adjusted their behavior by disengaging from the newly ineffective action in favor of exploring an alternative action. This finding demonstrates that stress impairs infants' ability to adjust their behavior to changing circumstances.

Emotional reactivity and parenting sensitivity interact to predict cortisol output in toddlers

Cortisol output in response to emotion induction procedures was examined at child age 24 months in a prospective longitudinal sample of 1,292 children and families in predominantly low-income and nonurban communities in two regions of high poverty in the United States. Multilevel analysis indicated that observed emotional reactivity to a mask presentation but not a toy removal procedure interacted with sensitive parenting to predict cortisol levels in children. For children experiencing high levels of sensitive parenting, cortisol output was high among children exhibiting high emotional reactivity and low among children exhibiting low emotional reactivity. For children experiencing low levels of sensitive parenting, cortisol output was unrelated to emotional reactivity.

Associations of Maternal and Infant Testosterone and Cortisol Levels With Maternal Depressive Symptoms and Infant Socioemotional Problems

This study examined the associations of testosterone and cortisol levels with maternal depressive symptoms and infant socioemotional (SE) problems that are influenced by infant gender. A total of 62 mothers and their very-low-birth weight (VLBW) infants were recruited from a neonatal intensive care unit at a tertiary medical center in the southeast United States. Data were collected at three time points (before 40 weeks' postmenstrual age [PMA] and at 3 months and 6 months of age corrected for prematurity). Measures included infant medical record review, maternal interview, biochemical assays of salivary hormone levels in mother-VLBWinfant pairs, and standard questionnaires. Generalized estimating equations with separate analyses for boys and girls showed that maternal testosterone level was negatively associated with depressive symptoms in mothers of boys, whereas infant testosterone level was negatively associated with maternal report of infant SE problems in girls after controlling for characteristics of mothers and infants and number of days post birth of saliva collection. Not surprisingly, the SE problems were positively associated with a number of medical complications. Mothers with more depressive symptoms reported that their infants had more SE problems. Mothers with higher testosterone levels reported that girls, but not boys, had fewer SE problems. In summary, high levels of testosterone could have a protective role for maternal depressive symptoms and infant SE problems. Future research need to be directed toward clinical application of these preliminary results.

What Dyadic Reparation Is Meant to Do: An Association with Infant Cortisol Reactivity

BACKGROUND

The latency to reparation of interactive mismatches (interactive repair) is argued to regulate infant distress on a psychobiological level, and maternal anxiety disorders might impair infant regulation.

SAMPLING AND METHODS

A total of 46 dyads (19 mothers with an anxiety disorder, 27 controls) were analyzed for associations between interactive repair and infant cortisol reactivity during the Face-to-Face-Still-Face paradigm 3-4 months postpartum. Missing cortisol values (n = 16) were imputed. Analyses were conducted on both the original and the pooled imputed data.

RESULTS

Interactive repair during the reunion episode was associated with infant cortisol reactivity (original data: p < 0.01; pooled data: p < 0.01) but not maternal anxiety disorder (p > 0.23). Additional stepwise regression analyses found that latency to repair during play (p < 0.01), an interaction between distress during the first trimester of pregnancy and latency to repair during reunion (p < 0.01) and infant self-comforting behaviors during the reunion episode (p = 0.04) made independent contributions to cortisol reactivity in the final regression model.

CONCLUSIONS

This is the first study demonstrating that interactive repair is related to infant psychobiological stress reactivity. The lack of a relation to maternal anxiety disorder may be due to the small sample size. However, this result emphasizes that infants respond to what they experience and not to the maternal diagnostic category.

Association between child cortisol levels in saliva and neuropsychological development during the second year of life

Exposure to highly elevated levels of cortisol has been linked with impairments in cognitive capacities in both children and adults. By contrast, moderate levels of cortisol may engender beneficial effects. The main aim of this study was to assess the association between child cortisol levels and neuropsychological development during the second year of life. A population-based birth cohort was established in the city of Sabadell (Catalonia, Spain) as part of the INMA (Environment and Childhood) Project. We assessed the cognitive and psychomotor development at the age of 14 months using the Bayley Scales of Infant Development (BSID). We included 302 children assessed during their second year of life for whom we had information on neuropsychological assessment and measurements of cortisol in saliva. Higher levels of cortisol were associated with better scores in BSID's mental scale. There was no association between cortisol levels and psychomotor test scores. We found a small positive association between duration of breastfeeding and child cortisol levels. This association was only found in boys. The results of this study suggest that moderate levels of cortisol in children could have small beneficial effects on their early neuropsychological development.

Children's negative emotions and ego-resiliency: longitudinal relations with social competence

We examined the relations of negative emotions in toddlerhood to the development of ego-resiliency and social competence across early childhood. Specifically, we addressed whether fear and anger/frustration in 30-month-old children (N = 213) was associated with the development of ego-resiliency across 4 time points (42 to 84 months), and, in turn, whether ego-resiliency predicted social competence at 84 months. Child anger/frustration negatively predicted the intercept of ego-resiliency at 42 months (controlling for prior ego-resiliency at 18 months) as well as the slope. Fear did not significantly predict either the intercept or slope of ego-resiliency in the structural model, although it was positively correlated with anger/frustration and was negatively related to ego-resiliency in zero-order correlations. The slope of ego-resiliency was positively related to children's social competence at 84 months; however, the intercept of ego-resiliency (set at 42 months) was not a significant predictor of later social competence. Furthermore, the slope of ego-resiliency mediated the relations between anger/frustration and children's later social competence. The results suggest that individual differences in anger/frustration might contribute to the development of ego-resiliency, which, in turn, is associated with children's social competence.

Child protection and adult depression: evaluating the long-term consequences of evacuating children to foster care during World War II

This paper combined data collected from war time government records with survey data including background characteristics, such as factors that affected eligibility, to examine the adult depression outcomes of individuals who were evacuated from Finland to temporary foster care in Sweden during World War II. Using war time government records and survey data for a random sample of 723 exposed individuals and 1321 matched unexposed individuals, the authors conducted least squares adjusted means comparison to examine the association between evacuation and adult depression (Beck Depression Inventory). The random sample was representative for the whole population of evacuees who returned to their biological families after World War II. The authors found no statistically significant difference in depressive symptoms during late adulthood between the two groups; for example, the exposed group had a 0.41 percentage points lower average Beck Depression Inventory score than the unexposed group (p = 0.907). This study provides no support for family disruption during early childhood because of the onset of sudden shocks elevating depressive symptoms during late adulthood.

Maternal sensitivity and infant and mother adrenocortical function across challenges

Findings regarding associations between maternal sensitivity and infant and mother adrenocortical function have been inconsistent. Nor have studies addressed the issue of intra-individual, between-challenge cortisol variability in the context of maternal sensitivity. In this study, we combine several design features aimed at sensitizing analyses to these issues. Cortisol secretion of 297 infants and their mothers was assessed in response to different challenges at 16 and 17 months. Extensive, structured observations of maternal sensitivity were conducted at infant age 16 months. Data were analyzed with multilevel modeling using an actor-partner interdependence model. We found that maternal sensitivity was related to infant, but not maternal, cortisol levels and also to infant-mother cortisol attunement. Infants of more sensitive mothers, as compared to infants of less sensitive mothers, showed greater cortisol variability across challenges, with relatively steep cortisol decreases and increases, depending on challenge. Mother and infant cortisol levels were highly correlated and this attunement was higher among dyads with more sensitive mothers than among dyads with less sensitive mothers. The results show nuanced attunement in a low-risk sample, with the infants of higher sensitivity mothers showing greater intra-individual variability across challenges. High cortisol response variability across challenges may simultaneously permit adaptation to threat and protect the infant from overexposure to corticosteroids.

Early adversity, socioemotional development, and stress in urban 1-year-old children

OBJECTIVE

To determine demographic, maternal, and child factors associated with socioemotional (SE) problems and chronic stress in 1-year-old children.

STUDY DESIGN

This was a prospective, longitudinal, community-based study, which followed mother-infant dyads (n = 1070; representative of race, education, and income status of Memphis/Shelby County, Tennessee) from midgestation into early childhood. Child SE development was measured using the Brief Infant-Toddler Social and Emotional Assessment in all 1097 1-year-olds. Chronic stress was assessed by hair cortisol in a subsample of 1-year-olds (n = 297). Multivariate regression models were developed to predict SE problems and hair cortisol levels.

RESULTS

More black mothers than white mothers reported SE problems in their 1-year-olds (32.9% vs 10.2%; P < .001). In multivariate regression, SE problems in blacks were predicted by lower maternal education, greater parenting stress and maternal psychological distress, and higher cyclothymic personality score. In whites, predictors of SE problems were Medicaid insurance, higher maternal depression score at 1 year, greater parenting stress and maternal psychological distress, higher dysthymic personality score, and male sex. SE problem scores were associated with higher hair cortisol levels (P = .01). Blacks had higher hair cortisol levels than whites (P < .001). In the entire subsample, increased hair cortisol levels were associated with higher parenting stress (P = .001), lower maternal depression score (P = .01), lower birth length (P < .001), and greater length at 1 year of age (P = .003).

CONCLUSION

Differences in maternal education, insurance, mental health, and early stress may disrupt SE development in children. Complex relationships between hair cortisol level in 1-year-olds and maternal parenting stress and depression symptoms suggest dysregulation of the child's hypothalamic-pituitary-adrenal axis.

Cortisol regulation in 12-month-old human infants: associations with the infants' early history of breastfeeding and co-sleeping

Experiences during early life are suggested to affect the physiological systems underlying stress responses, including the hypothalamic-pituitary-adrenal axis (HPA axis). While stressful early experiences have been associated with dysregulated HPA-axis functioning, positive early experiences, i.e. high maternal caregiving quality, contribute to more optimal HPA-axis functioning. Influences of other early caregiving factors, however, are less well documented. The goal of this study was to examine whether breastfeeding and co-sleeping during the first 6 months of life were associated with infant cortisol regulation, i.e. cortisol reactivity and recovery, to a stressor at 12 months of age. Participants were 193 infants and their mothers. Information on breastfeeding and co-sleeping was collected using weekly and daily sleep diaries, respectively, for the first 6 months of life. Co-sleeping was defined as sleeping in the parents' bed or sleeping in the parents' room. At 12 months of age, infants were subjected to a psychological stressor [Strange Situation Procedure (SSP); Ainsworth et al. 1978]. Salivary cortisol was measured prestressor and at 25, 40, and 60 min poststressor to measure reactivity and recovery. Regression analyses showed that after controlling for maternal sensitivity, infant attachment status, feeding, and sleeping arrangements at 12 months of age and other confounders, more weeks of co-sleeping predicted lower infant cortisol reactivity to the SSP. Also, more weeks of breastfeeding predicted quicker cortisol recovery. These results indicate that an early history of co-sleeping and breastfeeding contributes positively to cortisol regulation in 12-month-olds.

Hair cortisol reflects socio-economic factors and hair zinc in preschoolers

This study examined the relationship between children's hair cortisol and socioeconomic status of the family, as measured by parental education and income. Low family socioeconomic status has traditionally been considered a long-term environmental stressor. Measurement of hair cortisol provides an integrated index of cumulative stress exposure across an extended period of time. The present study is the first to examine the relationship between hair cortisol and parental education as well as parental income in a representative sample of preschoolers. Data on hair cortisol, family income, and parental education were collected for a representative sample of 339 children (Mean age=4.6 years; SD=.5 years) from across 23 neighbourhoods of the city of Vancouver, Canada. As maternal education was shown previously to be associated with hair zinc level, hair zinc measurements were included as well in order to explore potential relationships between hair zinc and hair cortisol. The relationship between hair cortisol and parental education was examined using hierarchical regression, with hair zinc, gender, age, and single parenthood included as covariates. Maternal and paternal education both were correlated significantly with hair cortisol (r=-0.18; p=.001). The relationship remained statistically significant even after controlling for all demographic covariates as well as for hair zinc and after taking the neighbourhood-level clustering of the data into account. Parental income, on the other hand, was not related significantly to children's hair cortisol. This study provides evidence that lower maternal and paternal education are associated with higher hair cortisol levels. As hair cortisol provides an integrated index of cortisol exposure over an extended time period, these findings suggest a possibly stable influence of SES on the function of the hypothalamic-pituitary-adrenal (HPA) axis. Cumulative exposure to cortisol during early childhood may be greater in children from low socio-economic backgrounds, possibly through increased exposure to environmental stressors.

Diurnal cortisol rhythm and cognitive functioning in toddlers: the Generation R Study

Little is known about the relationship between diurnal cortisol secretion patterns and cognitive function early in life. This population-based study examined whether diurnal cortisol rhythms and cognitive functioning in toddlers are related. Within the Generation R Study, parents of 364 infants (median age: 14.2 months) collected saliva samples at five moments during one day. We assessed the diurnal cortisol rhythm by calculating the area under the curve (AUC), the cortisol awakening response (CAR), and the diurnal slope. Verbal cognitive functioning and fine motor development was determined at age 18 months. Nonverbal cognitive functioning was assessed at age 30 months. A more positive CAR was associated with a lower risk of delay in language comprehension (OR per 1-SD CAR: 0.62, 95%CI: 0.40-0.98, p = .04), a lower risk of nonoptimal fine motor development (OR per 1-SD slope: 0.74, 95%CI: 0.57-0.96, p = .03), and a lower risk of delay in nonverbal cognitive development (OR per 1-SD CAR: 0.58, 95%CI: 0.38-0.90, p = .02). Also, children with flatter slopes had a lower risk of delay in nonverbal cognitive development (OR per 1-SD slope: 0.51, 95%CI: 0.34-0.76, p = .001). Higher AUC levels were associated with a higher risk of delay in language production. These results show that variations in diurnal cortisol rhythms are already associated with variations in cognitive functioning at a young age. Infants with a diurnal cortisol pattern indicative of less stress and more cortisol reactivity, that is, lower AUC levels and a more positive CAR, show a lower risk of delay in cognitive functioning as toddlers.

Altered stress responses in children exposed to early adversity: a systematic review of salivary cortisol studies

Pathological stress responses are implicated in numerous disorders. Hypothalamic-pituitary-adrenal axis function is influenced by gene-environment interaction, with early-life environmental adversity having long-lasting effects. We examine the evidence that, in humans, these effects are apparent from infancy. We systematically reviewed published findings on cortisol response to a stressor, in 0-5-year-olds already exposed to adversity. Adversity was defined as a negative environmental influence present post-conception. We searched Ovid MEDLINE (1950-May 2010), EMBASE (1980-May 2010) and PsychINFO (1806-May 2010). We included peer-reviewed, English language studies that analysed salivary cortisol before and after a standardised stressor. We identified 30 studies, of which 27 reported a significant effect of adversity on the cortisol response to stress. Six of these demonstrated an effect of prenatal substance exposure. Thirteen studies found that psychosocial adversity increased cortisol reactivity. Three studies reported that cortisol reactivity could be normalised by intervention programmes. The studies were heterogeneous, both in nature of adversity studied and in stressor used, precluding meta-analysis and assessment of publication bias. Our review presents evidence that adversity disrupts the stress response from an early age. Longitudinal studies are required to determine whether effects persist, alter with time, or are reversible with intervention.

Family relationships and children's stress responses

In this chapter, the theoretical and empirical associations between family relationships and children's responses to stressors are reviewed. Family relationships explored are primarily dyadic, representing the emphasis of past empirical research; these include parent-parent, parent-child, and sibling relationships. However, in recognition of the more complicated and interconnected nature of family relationships, also reviewed are associations between the broader family context and children's stress responses. Multiple measures of stress responses are considered, including both physiological and emotional responses to and recovery from stressful experiences. Overall, the studies reviewed suggest that poor-quality family environments, including those characterized by low emotional support or high conflict, are associated with dysregulated stress responses throughout childhood and adolescence. In contrast, children and adolescents in families with high emotional support or low conflict seem to be protected from developing stress regulatory problems. Limitations in this body of research as well as directions for future research are discussed.

Salivary cortisol levels are associated with resource control in a competitive situation in 19 month-old boys

Glucocorticoids (GCs) have been related to social rank in many studies across species, a particular rank giving rise to a particular stress-related physiological profile. Our aim was to examine the hypothesis that GCs levels in toddlers would be related to social dominance in a competitive resource situation. Subjects were 376 toddlers from the Quebec Newborn Twin Study. At 19 months of age, each subject was exposed to 2 unfamiliar situations known to be moderately stressful at that age. Saliva was collected before and after the unfamiliar situations, to assess pre-test and reactive cortisol. Then the toddler reaction to a competitive situation for a toy with an unfamiliar peer was assessed and we measured the proportion of time the child controlled the resource. In girls, no association between cortisol levels and the proportion of time the child got the toy was found. On the other hand, in boys, increased cortisol levels before the unfamiliar situation were significantly related to a decreased proportion of time they got the toy in the competitive situation (r(174) = -0.17, P = 0.02). These results show that even in toddlers with limited social experience, association between GCs levels and social dominance can be found, an association that is specific to boys.

Prenatal alcohol exposure and cortisol activity in 19-month-old toddlers: an investigation of the moderating effects of sex and testosterone

RATIONALE

Early exposure to stress and teratogenic substances have an impact on brain structures involved in cognition and mental health. While moderate-to-high levels of prenatal alcohol exposure (PAE) have repeatedly been associated with long-term neurodevelopmental deficits, no consensus has yet been reached on the detrimental effects of low-to-moderate PAE on the children's functioning, including the limbic-hypothalamic-pituitary-adrenal axis.

OBJECTIVES

The study aims to examine the association between low PAE and cortisol response to unfamiliar situations in 19-month-old children and to determine whether this association was moderated by sex and testosterone levels.

METHODS

Information regarding PAE, cortisol response to unfamiliar situations, and testosterone activity was available in a total of 130 children participating to the Québec Newborn Twin Study (Montréal, QC, Canada). Mother alcohol consumption during pregnancy was assessed via a semistructured interview conducted when the children were 6 months of age. The contribution of prenatal and postnatal confounds were examined.

RESULTS

Disrupted patterns of cortisol activity were observed only in PAE males. Testosterone tended to be negatively associated with the cortisol response, but not for PAE males, suggesting an altered sensitivity to the inhibitory effects of testosterone in these participants.

CONCLUSIONS

Low levels of PAE were associated with disrupted cortisol activity, and males may be at higher risk. These findings challenge the existence of a "safe level" of alcohol consumption during pregnancy and have public health implications.

Anxious attachment style and salivary cortisol dysregulation in healthy female children and adolescents

BACKGROUND

Attachment style has been linked with basal cortisol secretion in healthy adult women. We investigated whether dysregulation in basal cortisol secretion may be evident in younger healthy females.

METHODS

Sixty healthy females aged 9-18 years (mean 14.16, SD ± 2.63 years) participated in the Attachment Style Interview (ASI). Eight saliva samples, synchronised to awakening, were collected per day on two consecutive weekdays to examine the cortisol awakening response (CAR) and the subsequent diurnal decline.

RESULTS

Participants exhibiting an anxious attachment style had higher cortisol levels on awakening, in contrast to those who were securely attached. The anxious insecure group also showed an attenuated CAR compared to all other participants. Attachment style groups did not differ in cortisol secretion over the remainder of the day.

CONCLUSIONS

These findings indicate that the same pattern of cortisol dysregulation associated with disorder in adulthood manifests as a function of anxious (but not avoidant) insecure attachment style in females during healthy childhood and adolescence.

Psychological health throughout life and adult cortisol patterns at age 45 y

Population-based studies of cortisol and psychological health over long periods are rare. This study aims to establish whether cortisol levels in mid-adulthood are associated with chronicity and life-stage of psychological ill-health onset. We used data from the 1958 British birth cohort (3209 males; 3315 females) with cortisol measures 45 min post-waking (t1) and 3h later (t2) on the same day at 45y. Lifetime psychological health was identified from child and adult measures (ages 7, 11, 16, 23, 33, 42, 45y). t1 cortisol was lower by 3-4% in those with lifetime (child and adult) ill-health than those with no ill-health, after adjustment for socio-economic position and smoking. t1 cortisol was similarly lowered in those with adult onset of ill-health, but not among the group whose ill-health was of recent onset. t2 cortisol was elevated among all lifetime ill-health groups, by 6-9%, except for those whose ill-health did not extend beyond childhood. Simple analyses across the separate ages of follow-up suggest that elevations in t2 cortisol reflect associations for adult ill-health. Our study suggests that psychological ill-health over years and decades "blunts" post-awakening cortisol secretion, possibly reflecting HPA dysregulation due to social stressors.

Attachment, depression, and cortisol: Deviant patterns in insecure-resistant and disorganized infants

Both attachment insecurity and maternal depression are thought to affect infants' emotional and physiological regulation. In the current study, Strange Situation Procedure (SSP) attachment classifications, and cortisol stress reactivity and diurnal rhythm were assessed at 14 months in a prospective cohort study of 369 mother-infant dyads. Maternal lifetime depression was diagnosed prenatally using the Composite International Diagnostic Interview (CIDI). Insecure-resistant infants showed the largest increase in cortisol levels from pre- to post-SSP; the effect was even stronger when they had depressive mothers. Disorganized children showed a more flattened diurnal cortisol pattern compared to nondisorganized children. Findings are discussed from the perspective of a cumulative risk model.

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.

The predictive value of different infant attachment measures for socioemotional development at age 5 years

The predictive value of different infant attachment measures was examined in a community-based sample of 111 healthy children (59 boys, 52 girls). Two procedures to assess infant attachment, the Attachment Q-Set (applied on a relatively short observation period) and a shortened version of the Strange Situation Procedure (SSSP), were applied to the children at age 15 months and related to a comprehensive set of indicators of the children's socioemotional development at age 5 years. Three attachment measures were used as predictors: AQS security, SSSP security, and SSSP attachment disorganization. AQS security and SSSP security jointly predicted the security of the children's attachment representation at age 5. Apart from that, SSSP attachment disorganization was a better predictor of the children's later socioemotional development than were the other two early attachment measures. First, attachment disorganization was the only attachment measure to predict the children's later ego-resiliency, school adjustment, and dissociation. Second, as for the socioemotional measures at age 5 that also were related to AQS or SSSP security (i.e., peer social competence and externalizing problems), the attachment security measures did not explain any extra variance beyond what was explained by attachment disorganization.

Outcomes of children adopted from Eastern Europe

Behavioral problems are frequent among post-institutionalized Eastern European adoptees. However, risk factors related to outcomes have not been fully delineated. We evaluated 50 Eastern European adoptees, age 8—10 years, with their adoptive families for more than five years. Cognitive and behavioral outcomes and parenting stress were evaluated in relation to pre-adoptive risk factors, including arrival age, growth, and facial phenotype related to prenatal alcohol exposure. At follow-up, IQ and achievement scores were ≥ average in most children (≥74%). Behavioral and school problems were common (externalizing 44%, internalizing 18%, behavioral symptoms 50%, attention deficit hyperactivity disorder (ADHD) 46%, learning disabilities 40%, mental health disorders 28%); 38% had multiple problems. Behavioral problems correlated inversely with IQ. Parent stress was high and correlated with child externalizing behaviors and inversely to child full scale IQ. Children with “severe behavioral disturbances” (24%) were more likely to have had smaller head circumferences at arrival. Child's age at adoption related inversely to parent stress, possibly due to the longer duration of time that children resided with their families. “High/intermediate risk” phenotypic facial scores for prenatal alcohol exposure (58%) correlated with head circumference z scores at arrival and follow-up. Otherwise, arrival age, growth, and facial phenotype did not correlate with these specific outcome measures.