Fearful Temperament and Stress Reactivity Among Preschool-Aged Children

Could the impact of emotional states on learning in children vary with task difficulty?

Emotions are known to influence memory, in particular retention and recall, with positive emotions enhancing performances and negative emotions showing mixed effects. Although the influence of emotions on memory is well-established, their precise impact on the learning process remains a matter of debate and investigation. We implemented two experiments with children aged 6 to 8 years to examine how different emotional states affect training with tasks of varying difficulty. In Experiment 1, children were assessed in a letter recognition task and were assigned to positive, negative, or neutral emotional training conditions. Results showed significant performance improvements across all emotional conditions, indicating that emotional states did not differentially affect this task. In Experiment 2, using a more difficult non-word dictation task, significant improvements were found only in the positive and neutral conditions but not in the negative condition, suggesting that task difficulty modulates the impact of emotional states. These findings highlight the importance of considering both emotional states and task difficulty in educational settings. Positive and neutral emotions may facilitate cognitive processes under challenging conditions, whereas negative emotions might hinder them.

Emotions and interactive tangible tools for math achievement in primary schools

Introduction

Acquiring mathematical concepts is crucial for students' academic achievements, future prospects and overall well-being. This study explores the role of emotions in a symbolic number comparison task and the impact of the use of a tangible tool.

Methods

Fifty-nine healthy children aged 6 to 7 years participated in a between-subject study with two conditions for the modality, digital tools vs the use of pen and paper, and two conditions for emotions, positive vs neutral.

Results

The study provided evidence that positive emotions can improve task efficiency for pen and paper modality, and the use of the digital tool improves task efficiency with both positive and negative emotions.

Discussion

These findings suggest that addressing emotional factors before engaging in a symbolic task can enhance learning and that interactive technology may give a more significant benefit to students with less positive attitudes toward the task. Incorporating effective teaching methodologies that utilize tangible devices within a positive emotional context can foster engagement and achievement in mathematics, optimizing students' learning experiences.

Associations between affective temperament, perceived stress, and helping among Ukrainians and Poles in the context of the war in Ukraine

The Russian aggression of Ukraine has put millions of civilians under immense stress and forced many of them to leave their homes for safety and help. Poland became one of the leading destinations for waves of Ukrainians fleeing this war. The level of perceived stress in people who experienced war depends on various factors, including individual psychological variables. The main aim of this study was to analyze perceived stress levels and the predictive role of affective temperaments, as defined by Akiskal, for perceived stress in Ukrainians and Poles during the first year of the Russo-Ukrainian war. Secondly, we studied the relationship between affective temperament, stress, and commitment to help Ukrainian refugees. Self-report data from 410 Ukrainians and 146 Poles were collected. The results of this study shed light on perceived stress in war-affected populations and the role of affective temperaments in predicting its levels. We also demonstrated the links between affective temperament, perceived stress, and involvement in helping Ukrainian refugees. Understanding the mental status of people affected by war and its predictors is crucial to providing appropriate support and assistance to those in need.

Functional Gastrointestinal Symptoms in Children with Autism and ADHD: Profiles of Hair and Salivary Cortisol, Serum Leptin Concentrations and Externalizing/Internalizing Problems

BACKGROUND

Functional Gastrointestinal Disorders (FGIDs) present a higher prevalence in individuals with Neurodevelopmental Disorders (NDDs). The Stress System and the Gut-Brain axis (GBA) may mediate these relations. We aimed to assess the prevalence and profile of FGIDs in a clinical sample of children with Autism Spectrum Disorder (ASD) and Attention Deficit/Hyperactivity Disorder (ADHD) compared to typically developing children (TD) as well as to investigate possible relations between stress-related biomarkers and internalizing/externalizing problems in children with NDDS.

METHODS

In total, 120 children, aged between 4 and 12 years old, formed three groups (N = 40, each): ADHD, ASD and TD. Salivary cortisol, hair cortisol and serum leptin were measured.

RESULTS

The ASD group had more FGID problems than the TD group (p = 0.001). The ADHD and ASD groups had higher total internalizing/externalizing problems than the TD group (p < 0.0001, p < 0.0001, p = 0.005, respectively). Children with FGIDs showed more total, internalizing and externalizing problems compared to children without FGIDs (p < 0.0001, p < 0.0001, p = 0.041, respectively). The ADHD group showed lower AUCg values (p < 0.0001), while the hair cortisol was higher for the TD group (p < 0.0001).

CONCLUSION

In conclusion, children with NDDs had more FGID symptoms and present higher internalizing and externalizing problems. Children with ADHD and FGIDs had more internalizing problems compared to those without FGIDs. No differences in stress-related biomarkers were shown to differentiate children with NDDs with and without FGIDs. Future prospective studies including a greater number of children may elucidate the biological pathways linking these comorbidities.

Social versus non-social behavioral inhibition: Differential prediction from early childhood of long-term psychosocial outcomes

Behavioral inhibition (BI) is a temperamental style characterized by cautious and fearful behaviors in novel situations. The present multi-method, longitudinal study examined whether young children's observed and parent-reported BI in social versus non-social contexts predicts different long-term psychosocial outcomes. Participants (N = 279) were drawn from a longitudinal study of socioemotional development. BI in social contexts ("social BI") was measured via children's observed wariness toward unfamiliar adults and peers at 24 and 36 months and parents' reports of children's social fear/shyness at 24, 36, and 48 months. BI in non-social contexts ("non-social BI") was measured via children's observed fearful responses to masks and novel toys, and parents' reports of children's distress to non-social novelty at 9 months and non-social fear at 48 months. At 15 years, anxiety was assessed via adolescent- and parent-reports, and global internalizing and externalizing problems were assessed via parent-reports. Confirmatory factor analysis showed that a two-factor model fit the BI data significantly better than a single-factor model, providing evidence for the dissociation of BI in social versus non-social contexts. Social BI was uniquely associated with adolescent social anxiety, whereas non-social BI was specifically associated with adolescent separation anxiety. Neither social BI nor non-social BI predicted global internalizing and externalizing problems, providing evidence for the specific relations between BI and anxiety problems. Together, these results suggest that young children's inhibited responses in social versus non-social situations predict different subtypes of anxiety problems in adolescence, highlighting the multifaceted nature of BI and the divergent trajectories of different anxiety problems.

Latent profile analysis of diurnal cortisol patterns at the ages of 2, 3.5, and 5 years: Associations with childcare setting, child individual characteristics, and maternal distress

This study performed latent profile analysis from more than 4000 saliva cortisol samples collected from children at the ages of 2 (T1), 3.5 (T2), and 5 years (T3). Three clearly different cortisol profiles were identified. The largest group at every age point was the Low/Regular latent profile, in which the cortisol slopes followed typical diurnal variation. A smaller proportion of the children belonged to the latent profile with relatively Low/Flat slope, and a minority belonged to the High/Fluctuating latent group, where the overall cortisol values and variations between the slopes were clearly higher than in the other groups. Most of the children who belonged to the High/Fluctuating group were cared for at home, they had higher temperamental surgency and their mothers had more depressive symptoms than in the other latent profile groups. However, only moderate intraindividual stability in diurnal cortisol profiles was observed across the follow-up period. On average, half of the children moved between the groups from T1 to T3. Neither child temperament, social competence, nor sex explained the stability or movement between the groups across age. Variations in cortisol profiles may be caused by the child's age, and diurnal cortisol rhythm becomes more regular along with development. Methodological issues regarding saliva cortisol research in young children are discussed. Also, more longitudinal research is needed to clarify mechanisms between environmental as well as individual factors and possible dysregulation in a child's HPA axis functioning.

Associations between Autonomic and Endocrine Reactivity to Stress in Adolescence: Related to the Development of Anxiety?

Internalizing disorders in adolescence have been associated with disturbances in autonomic and endocrine functioning. Because the prefrontal cortex and the limbic system play a central role in regulating both the autonomic and the endocrine systems, their joint functioning is hypothesized to provide information about the potential development of internalizing symptoms throughout adolescence, notably in the preclinical stage. This hypothesis was tested in a sample of 198 adolescents from the general population. Heart rate variability (HRV) and skin conductance levels (SCLs) were measured before, during, and after a public speaking task. These autonomic parameters were associated with cortisol response to the task in the complete sample as well as in low- and high-anxiety adolescents separately. Self-reported social anxiety, low HRV, and high SCL recovery values were predictive of cortisol response. Importantly, in low-anxiety adolescents, only HRV during the task predicted the cortisol response, whereas, in their highly anxious peers, both HRV and SCL were strongly associated with this response. In the latter finding, age was a prominent factor. Additional analyses supported the idea that the interaction of autonomic and endocrine reactivity is subject to natural development. These findings provide evidence that adolescence might be a period of highly interactive emotional–neurobiological development, particularly with respect to the development of stress management skills.

Are fearful boys at higher risk for anxiety? Person-centered profiles of toddler fearful behavior predict anxious behaviors at age 6

Dysregulated fear (DF), the presence of fearful behaviors in both low-threat and high-threat contexts, is associated with child anxiety symptoms during early childhood (e.g., Buss et al., 2013). However, not all children with DF go on to develop an anxiety disorder (Buss and McDoniel, 2016). This study leveraged the data from two longitudinal cohorts (N = 261) to (1) use person-centered methods to identify profiles of fearful temperament, (2) replicate the findings linking DF to anxiety behaviors in kindergarten, (3) test if child sex moderates associations between DF and anxiety behaviors, and (4) examine the consistency of findings across multiple informants of child anxiety behaviors. We identified a normative fear profile (low fear in low-threat contexts; high fear in high-threat contexts), a low fear profile (low fear across both low- and high-threat contexts) and a DF profile (high fear across both low- and high-threat contexts). Results showed that probability of DF profile membership was significantly associated with child self-reported overanxiousness, but not with parent-reported overanxiousness. Associations between DF profile membership and overanxiousness was moderated by child sex such that these associations were significant for boys only. Additionally, results showed that probability of DF profile membership was associated with both parent-reported social withdrawal and observations of social reticence, but there were no significant associations with child self-report of social withdrawal. Results highlight the importance of considering person-centered profiles of fearful temperament across different emotion-eliciting contexts, and the importance of using multiple informants to understand associations with temperamental risk for child anxiety.

Characterizing difficulties with emotion regulation in toddlers with autism spectrum disorder

Background

Difficulties with emotion regulation (ER) underlie emotional/behavioral challenges and co-occurring psychiatric symptoms in autism spectrum disorder (ASD), yet very little is known about the early development of emotion dysregulation. The present study aimed to identify differences in positive and negative emotional reactivity and regulation strategies in toddlers with and without ASD.

Method

Nine tasks from the Laboratory Temperament Assessment Battery (Lab-TAB) were completed with 37 toddlers with and without ASD (22-28 months). Video-recordings of these tasks were coded by research assistants using a behavioral coding scheme tapping facial, bodily, and vocal affect and the frequency of ER strategies. Mixed model analyses were performed to examine the mean affect and total regulation strategies across each task and t-tests were conducted to assess the types of ER strategies utilized.

Results

Toddlers with ASD showed significantly less positive affect and greater frustration compared to non-ASD toddlers; reactivity was comparable between the groups for fear. Both groups used ER strategies in a similar pattern across tasks, with the exception that toddlers with ASD more often engaged in distraction to regulate. Effects of age and developmental level are discussed.

Conclusions

Toddlers with ASD were robustly characterized by greater frustration and lower joy despite frequent and age appropriate attempts to regulate their emotions. This study provides preliminary evidence that observable indicators of emotion dysregulation are present by two years of age. Clinical implications and future research directions are discussed.

Children's diurnal cortisol output and temperament in two different childcare settings at 2 and 3.5 years of age

Prior research suggests that child temperament may play an important role in early childhood stress regulation. We compared children's diurnal cortisol and the association between cortisol and temperament in two different childcare settings. Cortisol was measured from saliva samples over 2 days in children (N = 84) attending out-of-home childcare and in children (N = 27), who were cared for at home at the age of 3.5 years. There was no difference between the childcare groups in total diurnal cortisol. However, of the individual measurements, afternoon cortisol levels were higher in the out-of-home childcare group during their childcare day when compared with their home day. Child temperament was not associated with total diurnal cortisol. Comparison with our prior measurements showed that the association between temperamental surgency/extroversion and total diurnal cortisol diminished along with the child age from 2 to 3.5 years in both childcare settings. This may indicate that more extroverted children are physiologically more reactive to environmental stimuli when they are younger, but this association does not appear as the children develop. Our results further suggest that the afternoon hours in the out-of-home childcare may be demanding and accelerate the hypothalamus-pituitary-adrenal axis activation in young children independent of their age.

Longitudinal prospective study examining the effects of the timing of prenatal stress on infant and child regulatory functioning: the Michigan Prenatal Stress Study protocol

INTRODUCTION

A considerable literature implicates prenatal stress as a critical determinant of poor psychological functioning in childhood and beyond. However, knowledge about whether the timing of prenatal stress differentially influences the development of child outcomes, including psychopathology, is virtually unknown. The primary aim of our study is to examine how the timing of prenatal stress differentially affects early childhood regulatory functioning as a marker of psychopathology. Our second aim is to examine the mediating effects of maternal physiological and psychological factors during pregnancy. Our third aim is to examine the moderating effects of postnatal factors on child regulatory functioning. Our project is the first longitudinal, prospective, multimethod study addressing these questions.

METHODS AND ANALYSIS

Our ongoing study recruits pregnant women, oversampled for intimate partner violence (a common event-based stressor allowing examination of timing effects), with data collection starting at pregnancy week 15 and concluding 4 years post partum. We aim to have n=335 mother-child dyads. We conduct a granular assessment of pregnancy stress (measured weekly by maternal report) in order to reveal sensitive periods during fetal life when stress particularly derails later functioning. Pattern-based statistical analyses will be used to identify subgroups of women who differ in the timing of their stress during pregnancy and then test whether these patterns of stress differentially predict early childhood self-regulatory outcomes.

ETHICS AND DISSEMINATION

Due to the high-risk nature of our sample, care is taken to ensure protection of their well-being, including a safety plan for suicidal ideation and a safety mechanism (exit button in the online weekly survey) to protect participant data privacy. This study was approved by Michigan State University Institutional Review Board. Dissemination will be handled by data sharing through National Institute of Child Health and Human Development Data and Specimen Hub (DASH), as well as through publishing the findings in journals spanning behavioural neuroendocrinology to clinical and developmental psychology.

Associations between hair and salivary cortisol, salivary alpha-amylase, and temperament dimensions among 3-6-year-olds

Associations between hair cortisol concentration (HCC), diurnal salivary cortisol (sCort) and alpha-amylase (sAA), and temperament dimensions were examined among 3-6-year-old Finnish children (n = 833). Children's hair samples were collected at preschool, while parents collected five saliva samples from children during one weekend day and completed a questionnaire assessing child's temperament dimensions i.e. surgency, negative affectivity, and effortful control (HCC, n = 677; AUCg of sAA, n = 380; AUCg of sCort, n = 302; temperament dimensions, n = 751). In linear regression analysis, diurnal sCort associated positively with HCC, the association persisting after adjustments (β 0.31, 95% CI 0.20-0.42). In logistic regression analysis, increasing scores in effortful control associated with higher likelihood of having high HCC (OR 1.47, 95% CI 1.07-2.03), the association slightly attenuating to non-significant after adjustments. Otherwise, no clear indication for associations between temperament and stress-related biomarkers were found.

Stress-induced plasma cortisol concentrations in infancy are associated with later parenting behaviors in female rhesus macaques (Macaca mulatta)

Few studies have longitudinally assessed the relationship between infant stress reactivity and future parenting style. Studies show that stress-induced plasma cortisol concentrations are stable over development and that they can be utilized as a marker for stress reactivity. This study investigates the relationship between stress-induced plasma cortisol concentrations in infancy and later parenting behavior in a translational nonhuman primate model. We hypothesized that higher stress-induced cortisol levels in infancy would predict impairments in maternal behaviors in adulthood. Subjects were rhesus macaque females (N = 122; Macaca mulatta), assessed as infants and again as mothers. At 3-4 months of age, subjects underwent a standardized BioBehavioral Assessment during which blood samples were obtained and they were assessed for behaviorally inhibition. Approximately 7 years later, subjects were observed as they interacted with their own offspring for four 300-s sessions. Typical rhesus monkey mother-offspring behaviors were recorded, including approaches and leaves and maternal cradling. Results showed that subjects' stress-induced cortisol concentrations and whether they exhibited behavioral inhibition as infants predicted later maternal behavior, with high cortisol concentrations and behavioral inhibition predicting high rates of offspring approaches and leaves and low rates of maternal cradling. Results also showed that higher stress-induced cortisol concentrations in infancy predicted higher scores on the Brown Index, an indication that the subjects' offspring, rather than the subject themselves, initiated changes in proximity. Taken together, these results suggest that individuals that exhibit higher stress-induced cortisol concentrations and behavioral inhibition at 3-4 months of age are at risk for engaging in less sensitive parenting behaviors as adults. To the extent that these findings generalize to humans, they suggest an important link between stress-induced cortisol concentrations and behavioral inhibition in infancy and behavior later in life, such that early-life stress reactivity can serve as a marker for later parenting behavior.

Early maternal and paternal caregiving moderates the links between preschoolers' reactivity and regulation and maturation of the HPA-immune axis

While early caregiving and child's temperamental dispositions work in concert to shape social-emotional outcomes, their unique and joint contribution to the maturation of the child's stress and immune systems remain unclear. We followed children longitudinally from infancy to preschool to address the buffering effect of early parenting on the link between temperamental dysregulation and hypothalamic-pituitary-adrenal (HPA)-immune axis in preschool-aged children. Participants included 47 typically developing children and their 94 parents in both mother-father and two-father families followed across the first 4-years of family formation. In infancy, we observed parent-infant synchrony and measured parental oxytocin; in preschool, we observed temperamental reactivity and self-regulation and assessed children's cortisol and secretory Immunoglobulin A (s-IgA), biomarkers of the stress and immune systems. Greater self-regulation and lower negative emotionality were associated with lower baseline s-IgA and cortisol, respectively. However, these links were defined by interactive effects so that preschoolers with low self-regulation displayed higher s-IgA levels only in cases of low parent-infant synchrony and negative emotionality linked with greater baseline cortisol levels only when parental oxytocin levels were low. Results emphasize the long-term stress-buffering role of the neurobiology of parental care, demonstrate comparable developmental paths for mothers and fathers, and delineate the complex developmental cascades to the maturation of children's stress-management systems.

Sensory processing and cortisol at age 4 years: Procedural pain-related stress in children born very preterm

Children born preterm display altered sensory processing, which may manifest as hyper- and/or hypo-sensitivity to sensory information. In this vulnerable population, exposure to neonatal pain-related stress is associated with altered stress regulation, as indexed by alterations in cortisol levels. It is unknown whether sensory processing behaviors are also affected by early life adversity, and whether dysregulated cortisol is related to sensory processing problems in preterm children. We examined relationships between neonatal pain-related stress, sensory processing profiles and cortisol levels at age 4 years, and whether pathways were sex-specific. In a longitudinal prospective cohort study, N = 146 infants born 24-32 weeks gestational age were recruited from BC Women's Hospital, Vancouver, BC, Canada; neonatal factors were collected from daily chart review. At age 4 years, saliva to assay cortisol was collected three times across cognitive assessment (pre-test, during, end) and parents completed the Short Sensory Profile questionnaire. Using generalized linear modeling, independent of other neonatal factors, higher number of invasive procedures (pain/stress) was associated with more sensory processing problems (total, hypo- and hyper-sensitivity) for girls only. After accounting for neonatal factors, greater cortisol output across the assessment was associated with more total sensory processing problems in girls only, and hypersensitivity to sensory input in both boys and girls. Findings suggest that in children born very preterm, how a child responds to sensory input and cortisol reactivity to stress are related but may have different precursors. Girls may be somewhat more susceptible to neonatal pain-related stress exposure in relation to sensory processing at preschool age.

Children's hair cortisol as a biomarker of stress at school: a follow-up study

In a previous study, we examined hair cortisol concentrations (HCCs) in children when first entering elementary school (at 4 years). In this follow-up study, we examined their HCC when they entered third grade (at 6 years), where the more playful first grades proceed into a more formal learning setting. Participants were 30 6-year-old children (14 boys). Hair samples (≥5 cm) were collected 2 months after the summer holidays. Hair analysis was conducted using two 2-cm long segments, reflecting the first 2 months of school attendance in grade 3 (the scalp-near segment), and 2 months prior to the start in grade 3. Between these two sections, we left a gap of 1 cm to avoid overlap of periods (due to differences in hair growth rate). Children showed a significant increase in cortisol levels when they entered third grade. This increase was not associated with social fearfulness or academic achievement, but did show significant associations with inhibitory control: children with less inhibitory control had higher cortisol levels after entering third grade, and larger increases in cortisol than children with higher scores on inhibitory control. This suggests that the ability to inhibit or control impulsive responsivity is important for children's stress regulation when making the transition to a more formal school environment.

Child Temperament and Total Diurnal Cortisol in Out-of-Home Center-Based Child Care and in At-Home Parental Care

The association between child temperament characteristics and total diurnal saliva cortisol in 84 children (M = 2.3 years, SD = 0.6) attending out‐of‐home, center‐based child care and 79 children (M = 2.0 years, SD = 0.5) attending at‐home parental care was examined. Saliva samples were collected during two consecutive days, that is, Sunday and Monday, with four samples taken per day. While children higher in surgency had higher total diurnal cortisol production, we did not find evidence that temperament moderated the associations between child‐care context and total diurnal cortisol. Negative affectivity and effortful control were not related to cortisol output. Our findings suggest that temperamental surgency may be associated with higher total cortisol production in early childhood across child‐care settings.

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.

Revisiting the double-edged sword of self-regulation: Linking shyness, attentional shifting, and social behavior in preschoolers

Although children's self-regulation has been conceptualized positively, there may be individual differences in self-regulatory processes, some of which might not be adaptive depending on temperamental factors. We examined whether individual differences in children's self-regulation (i.e., inhibitory control and attentional shifting) moderated the association between shyness and social behavior in multiple social contexts (N = 156 children, 74 girls; M_age = 4.06 years, SD = 0.78). Only in children with high attentional shifting was shyness associated with lower levels of social support seeking during a frustration task and with lower levels of social engagement during a stranger approach task. These results were not attributable to differences in baseline physiological arousal indexed by respiratory sinus arrhythmia. These findings suggest that for some shy children, high levels of self-regulation may be less adaptive, leading to rigidity or over-control in some social contexts, possibly hindering social interaction.

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.

Gut microbiota composition is associated with temperament traits in infants

BACKGROUND

One of the key behavioral phenotypes in infancy are different temperament traits, and certain early life temperament traits have been shown to precede later mental health problems. Differences in the gut microbiota composition (GMC) have been suggested to link with neurodevelopment. For example, toddler temperament traits have been found to associate with differences in GMC; however, studies in infants are lacking although infancy is a rapid period of neurodevelopment as well as GM development. Thus, we aimed to investigate association between infant GMC and temperament.

METHODS

The study population (n = 301, 53% boys) was drawn from the FinnBrain Birth Cohort Study. Stool samples were collected from the 2.5-month-old infants and sequenced with 16S Illumina MiSeq platform. GMC taxonomic composition (at Genus and OTU level), observed sample clusters, diversity and richness were investigated in relation to the maternal reports of Infant Behavior Questionnaire -Revised (IBQ-R) at the age of 6 months.

RESULTS

Three sample clusters (Bifidobacterium/Enterobacteriaceae, Bacteroides, V. Dispar) based on GMC were identified, of which Bifidobacterium/Enterobacteriaceae-cluster presented with higher scores on the IBQ-R main dimension regulation and its subscale duration of orienting compared to Bacteroides-cluster. The clusters associated with temperament in a sex-dependent manner. The IBQ-R main dimension surgency (positive emotionality) was associated positively both with genus Bifidobacterium and Streptococcus. Alpha diversity had a negative association with negative emotionality and fear reactivity.

CONCLUSION

This is the first study demonstrating associations, but not causal connections, between GMC and temperament in young infants in a prospective design.

The impact of maternal stress on infant alpha-amylase is buffered by high infant regulation and low infant negative reactivity

This study examined the main and interactive effects of maternal perceived stress and infant temperament-surgency, negative affectivity, and orienting/regulation-on infant salivary alpha-amylase (sAA) responses to stress. Saliva samples were collected prior to and following two naturalistic stressors: maternal separation conducted at 9 months and blood draw/immunizations conducted at 12 months. sAA area under the curve (AUC) was computed to determine response of the sympathetic nervous system to each stressor. Results revealed significant interactions of maternal stress and infant negative affectivity and orienting/regulation with sAA AUC. Relations between maternal stress and infant sAA AUC were stronger among infants with higher levels of negative affectivity and lower levels of orienting/regulation. These results highlight the need to examine both infant characteristics and environmental factors when investigating the development of stress response systems.

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.

Immune and neuroendocrine correlates of temperament in infancy

There is now a clear focus on incorporating, and integrating, multiple levels of analysis in developmental science. The current study adds to research in this area by including markers of the immune and neuroendocrine systems in a longitudinal study of temperament in infants. Observational and parent-reported ratings of infant temperament, serum markers of the innate immune system, and cortisol reactivity from repeated salivary collections were examined in a sample of 123 infants who were assessed at 6 months and again when they were, on average, 17 months old. Blood from venipuncture was collected for analyses of nine select innate immune cytokines; salivary cortisol collected prior to and 15 min and 30 min following a physical exam including blood draw was used as an index of neuroendocrine functioning. Analyses indicated fairly minimal significant associations between biological markers and temperament at 6 months. However, by 17 months of age, we found reliable and nonoverlapping associations between observed fearful temperament and biological markers of the immune and neuroendocrine systems. The findings provide some of the earliest evidence of robust biological correlates of fear behavior with the immune system, and identify possible immune and neuroendocrine mechanisms for understanding the origins of behavioral development.

Impaired cardiac profile in adolescents with an increasing trajectory of anxiety when confronting an acute stressor

Maladaptive patterns of cardiac adjustment to stress in adolescents may reveal their vulnerability to anxiety disorders (ADs). Traditional research in this field has focused on anxiety levels, whereas the time course of anxiety has rarely been considered. Nevertheless, since overall anxiety decreases as adolescence progresses, increasing time courses are clinically relevant and can be associated with maladaptive contextual adjustment. In this study, the cardiac pattern of adjustment to stress in adolescents with increasing anxiety was analysed. A sample of 44 adolescents (M = 14.88 years, SD = 0.53, 45.45% boys) were exposed to a socially relevant stress induction protocol, and their cardiac functioning was recorded. Participants with a trajectory of increasing anxious symptomatology over a 12-month period (n = 24) showed attenuated heart rate levels in the stage of maximum stress in comparison to their non-increasing anxious counterparts (p < 0.05), as well as a heightened pattern of sample entropy throughout the stress induction (p < 0.05). These findings suggest a loss of cardiac flexibility in those adolescents at risk of ADs when confronting an acute stressor.

Child temperament and teacher relationship interactively predict cortisol expression: The prism of classroom climate

Entry into kindergarten is a developmental milestone that children may differentially experience as stressful, with implications for variability in neurobiological functioning. Guided by the goodness-of-fit framework, this study tested the hypothesis that kindergarten children's (N = 338) daily cortisol would be affected by the "match" or "mismatch" between children's temperament and qualities of the classroom relational context. The robustness of these associations was also explored among a separate sample of children in third grade (N = 165). Results among kindergarten children showed negative affectivity and overcontrolled temperament were positively related to cortisol expression within classrooms characterized by lower levels of teacher motivational support, but there was no relation between temperament and cortisol when motivational support was higher. Among third-grade children, negative affectivity was marginally positively related to cortisol at lower levels of teacher-child closeness and unrelated at higher levels of teacher-child closeness. Findings suggest children's cortisol expression depends on the extent to which specific temperamental characteristics "fit" within the relational and contextual qualities of the classroom environment, particularly as children navigate the new roles and relationships that emerge during the transition to formal schooling. Developmentally informed neurobiological research in classrooms may contribute to tailored programmatic efforts to support children's school adjustment.

Preschool Fantasy-Reality Discrimination: Influences of Trait and Primed Fearfulness

Distinguishing between fantasy and reality is an important developmental milestone, achieved in the preschool years, that has been linked to children's cognitive capabilities and emotional knowledge. The authors examined the influence of both trait and prime fearfulness on preschoolers' ability to differentiate between fantastic and real situations. Forty 3-5-year-old preschoolers were administered a fearfulness assessment, a standard theory-of-mind task, and a fantasy-reality discrimination task (with or without a fear prime). When primed to experience fear, participants who were high in trait fearfulness made more mistakes distinguishing between fantastic and real events than did participants who were low in trait fearfulness. In the absence of a fear prime there was no difference in performance between these two groups. These findings were independent of participants' age, gender, and theory of mind abilities and suggest that preschoolers who are high in trait fearfulness are more prone to difficulty in discriminating between fantasy and reality when actively experiencing fear. This study illuminates important factors that contribute to the errors in fantasy-reality judgments frequently seen in preschoolers.

The interaction between parenting and children's cortisol reactivity at age 3 predicts increases in children's internalizing and externalizing symptoms at age 6

Little is known about the role of stress reactivity in the emergence of psychopathology across early childhood. In this longitudinal study, we tested the hypothesis that child cortisol reactivity at age 3 moderates associations between early parenting and children's internalizing and externalizing symptoms from age 3 to age 6. One hundred and sixty children were assessed at age 3, and 135 children were reassessed at age 6. At age 3, we exposed children to stress-inducing laboratory tasks, during which we obtained four salivary cortisol samples, and parental hostility was assessed using an observational parent-child interaction task. At ages 3 and 6, child psychiatric symptoms were assessed using a clinical interview with parents. The results indicated that the combination of high child cortisol reactivity and high observed parental hostility at age 3 was associated with greater concurrent externalizing symptoms at age 3 and predicted increases in internalizing and externalizing symptoms from age 3 to age 6. Findings highlight that increased stress reactivity, within the context of hostile parenting, plays a role in the emergence of psychopathology from preschool to school entry.

Toddler parasympathetic regulation and fear: Links to maternal appraisal and behavior

There is a growing recognition that parental socialization influences interact with young children's emerging capacity for physiological regulation and shape children's developmental trajectories. Nevertheless, the transactional processes linking parental socialization and physiological regulatory processes remain not well understood, particularly for fear-prone toddlers. To address this gap in the literature, the present study investigated the biopsychosocial processes that underlie toddlers' fear regulation by examining the relations among toddler parasympathetic regulation, maternal appraisal, and parenting behaviors. Participants included 124 mothers and their toddlers (Mage  = 24.43 months), who participated in a longitudinal study of temperament and socio-emotional development. Toddlers' parasympathetic reactivity was found to moderate the links between maternal anticipatory appraisal of child fearfulness and (a) maternal provision of physical comfort and (b) preschool-age child inhibition. Additionally, maternal comforting behaviors during the low-threat task predicted preschool-age separation distress, specifically for toddlers demonstrating a low baseline RSA.

Dispositional and Environmental Predictors of the Development of Internalizing Problems in Childhood: Testing a Multilevel Model

This investigation evaluated a multilevel model of dispositional and environmental factors contributing to the development of internalizing problems from preschool-age to school-age. In a sample of 375 families (185 daughters, 190 sons) drawn from three independent samples, preschoolers' behavioral inhibition, cortisol and gender were examined as moderators of the links between mothers' negative parenting behavior, negative emotional characteristics, and socioeconomic status when children were 3.95 years, and their internalizing problems when they were 8.34 years. Children's dispositional characteristics moderated all associations between these environmental factors and mother-reported internalizing problems in patterns that were consistent with either diathesis-stress or differential-susceptibility models of individual-environment interaction, and with gender models of developmental psychopathology. Greater inhibition and lower socioeconomic status were directly predictive of more teacher reported internalizing problems. These findings highlight the importance of using multilevel models within a bioecological framework to understand the complex pathways through which internalizing difficulties develop.

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.

Differential Susceptibility of the Developing Brain to Contextual Adversity and Stress

A swiftly growing volume of literature, comprising both human and animal studies and employing both observational and experimental designs, has documented striking individual differences in neurobiological sensitivities to environmental circumstances within subgroups of study samples. This differential susceptibility to social and physical environments operates bidirectionally, in both adverse and beneficial contexts, and results in a minority subpopulation with remarkably poor or unusually positive trajectories of health and development, contingent upon the character of environmental conditions. Differences in contextual susceptibility appear to emerge in early development, as the interactive and adaptive product of genetic and environmental attributes. This paper surveys what is currently known of the mechanisms or mediators of differential susceptibility, at the levels of temperament and behavior, physiological systems, brain circuitry and neuronal function, and genetic and epigenetic variation. It concludes with the assertion that differential susceptibility is inherently grounded within processes of biological moderation, the complexities of which are at present only partially understood.

Early childhood cortisol reactivity moderates the effects of parent-child relationship quality on the development of children's temperament in early childhood

Positive parenting has been related both to lower cortisol reactivity and more adaptive temperament traits in children, whereas elevated cortisol reactivity may be related to maladaptive temperament traits, such as higher negative emotionality (NE) and lower positive emotionality (PE). However, no studies have examined whether hypothalamic-pituitary-adrenal axis activity, as measured by cortisol reactivity, moderates the effect of the quality of the parent-child relationship on changes in temperament in early childhood. In this study, 126 3-year-olds were administered the Laboratory Temperament Assessment Battery (Lab-TAB; Goldsmith et al., 1995) as a measure of temperamental NE and PE. Salivary cortisol was collected from the child at 4 time points during this task. The primary parent and the child completed the Teaching Tasks battery (Egeland et al., 1995), from which the quality of the relationship was coded. At age 6, children completed the Lab-TAB again. From age 3 to 6, adjusting for age 3 PE or NE, a better quality relationship with their primary parent predicted decreases in NE for children with elevated cortisol reactivity and predicted increases in PE for children with low cortisol reactivity. Results have implications for our understanding of the interaction of biological stress systems and the parent-child relationship in the development of temperament in childhood.

Correlates and consequences of toddler cortisol reactivity to fear

Cortisol reactivity to fear-eliciting stimuli during toddlerhood may represent an indicator of risk for anxiety spectrum problems and other maladjustment. Thus, it is important to understand factors that may contribute to cortisol reactivity as well as those that determine its predictive relation to early emerging anxiety. In this vein, the current study investigated maternal comforting behaviors, both solicited and unsolicited by the toddler, as correlates of cortisol reactivity at 2years of age. Furthermore, we investigated maternal comforting behaviors and behavioral indicators of fear in both a low-threat and a high-threat context as moderators of the relation between cortisol reactivity at age 2 and change in anxiety from age 2 to age 3. The sample comprised 99 2-year-old toddlers and their mothers. Toddlers provided saliva samples at baseline and after a fear-eliciting stimulus that were assayed for cortisol. Mothers were observed for comforting behavior while interacting with their toddlers in laboratory tasks and completed questionnaires about their toddlers' anxiety. Results indicated that unsolicited (spontaneous) comforting behavior related to toddler cortisol reactivity above and beyond solicited comforting and the level of fear toddlers displayed in the same task. Moreover, fear in a low-threat context, but not in a high-threat context, moderated the relation between cortisol reactivity and change in anxiety, such that cortisol reactivity had a positive relation to anxiety at extreme levels of low-threat fear. Results suggest the importance of considering the caregiving environment and context-specific fear in understanding the nature of cortisol reactivity during the toddler years.

Relations between temperamental fear and risky pedestrian behavior

OBJECTIVE

Child pedestrian injury poses a significant global public health challenge. This study examines relations between temperamental fear and children's risky pedestrian behavior, utilizing mediation analytic strategies to study underlying mechanisms of the hypothesized relation.

METHODS

As part of a larger study, 240 seven- and eight-year-old children completed 30 crossings in a virtual reality (VR) pedestrian environment. Three pedestrian behaviors were considered: start gap (lag after a traffic gap appears before child initiates crossing into the gap), time to contact (TTC; gap between avatar and the lead oncoming vehicle), and hits (collisions with vehicles in simulated crossings). Temperamental fear was measured by parent report.

RESULTS

Fearful children were more likely to be struck by virtual vehicles, and the relation between fear and risky pedestrian behaviors was mediated by start gap and TTC. Specifically, children who were temperamentally more fearful were more likely to hesitate before initiating crossing, which led to shorter gaps between themselves and the oncoming vehicle, hence causing them to be more likely to be hit by virtual vehicles. Gender interacted with fear, such that fearful girls were most likely to be hit.

CONCLUSIONS

Both temperamental fear and gender influenced the risk of child pedestrian injuries. Delayed entry into traffic and shorter gaps between children and oncoming vehicles may underlie this relation. Future research should explore how these factors might influence the effectiveness of prevention programs.

Maternal emotional availability at bedtime and infant cortisol at 1 and 3 months

BACKGROUND

Previous work has shown that early experience influences infant cortisol secretion. Few studies, however, have examined associations between parenting quality and cortisol levels and patterning in very young infants.

AIMS

This study examined linkages between maternal emotional availability (EA) during a routine caregiving task, bedtime, and infant cortisol in the first 3 months of life. Concurrent and longitudinal associations between maternal EA and infant cortisol were examined.

STUDY DESIGN

Families were visited when their infants were 1 and 3 months old. Video equipment was set up in order to record the infant's bedtime routine. Parents were provided with materials with which to take saliva samples from their infants at late afternoon, bedtime, and the following morning.

SUBJECTS

At 1 month, participants were 96 mothers and infants living in a rural U.S. state. Data were available for 88 mothers and infants at 3 months.

OUTCOME MEASURES

Maternal EA was scored from videotapes of bedtime at each age point. Infant cortisol was assessed from the saliva samples taken by parents.

RESULTS

Regression analyses indicated that at 1 and 3 months of age, infants of more emotionally available mothers showed lower levels of cortisol secretion across the night than infants of less emotionally available mothers. Additionally, multilevel model analyses indicated that infants of more emotionally available mothers showed greater evidence of a decline in their cortisol levels across the evening, followed by an increase across the nighttime into the morning in their cortisol at 3 months.

CONCLUSIONS

Findings suggest that maternal care in the context of a routine caregiving task is associated with lower stress reactivity and with earlier circadian patterning in very young infants.

Children's hair cortisol as a biomarker of stress at school entry

Quantification of cortisol in scalp hair seems a promising measurement for long-term cortisol levels, and thereby a biomarker for stress. We examined hair cortisol concentrations (HCC) in children when first entering elementary school. Participants were 42 children (45% boys) with a mean age of 4.2 years (SD = 0.42 months). Hair samples (≥5 cm) were collected 2 months after school entry. Hair analysis was conducted using two 2-cm long segments, reflecting the first 2 months of school attendance (the scalp-near segment) and 2 months prior to school entry. HCC were higher after school entry than before, especially for fearful children. Alterations in HCC were not moderated by experience in group daycare before school entry. Thus, HCC suggest that starting elementary school is accompanied by increased stress hormone levels in young (in particular fearful) children.

HPA axis reactivity in early childhood: associations with symptoms and moderation by sex

Sex differences in rates of internalizing disorders have been attributed in part to heightened sensitivity to stress in females. While the sex difference in disorder rates becomes most pronounced in adolescence, developmental research suggests that stress reactivity in girls may be related to elevated internalizing symptoms even in childhood. We therefore examined whether child sex moderated associations between symptoms of psychopathology and cortisol reactivity to a standardized stress task in 409 three-year-old community-dwelling children. Anxious symptoms were associated with elevated cortisol reactivity, but only in girls. Externalizing symptoms were unrelated to baseline cortisol or cortisol reactivity, and no evidence for moderation by child sex was found. Results suggest that cortisol reactivity to stress in early childhood has a sex-specific association with girls' internalizing symptoms.

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.

Stress proneness in molecularly defined long QT syndrome: a study using temperament assessment by behavioural inhibition system scale

The long QT syndrome (LQTS) is an inherited cardiac disorder that predisposes the mutation carrier to ventricular arrhythmias that can lead to sudden death. The objective of the present study was to replicate the previous finding in terms of stress-related temperament trait, i.e. behavioural inhibition system (BIS). The study subjects included 583 LQTS mutation carriers (256 symptomatic and 327 asymptomatic) from the Finnish LQTS registry and 79 healthy subjects randomly derived from the population-based sample of the Young Finns Study. Symptomatic and asymptomatic LQTS mutation carriers did not differ from each other on BIS (3.27 versus 3.24, p > 0.05), whereas LQTS mutation carriers scored higher on BIS than the comparison group derived from the representative population-based sample (3.25 versus 2.99, p = 0.003, η² = 0.014). BIS was significantly higher in women than in men (3.32 versus 3.06, p < 0.001, η² = 0.017). The results confirm our previous finding of higher stress proneness of LQTS mutation carriers. Their innate stress proneness may have relevance because it increases our understanding on the role of stress in the manifestation of symptoms.

Interparental aggression and infant patterns of adrenocortical and behavioral stress responses

Drawing on emotional security theory, this study examined linkages between interparental aggression, infant self-regulatory behaviors, and patterns of physiological and behavioral stress responses in a diverse sample of 735 infants residing in predominately low-income, non-metropolitan communities. Latent profile analysis revealed four classes of adrenocortical and behavioral stress-response patterns at 7 months of age, using assessments of behavioral and cortisol reactivity to an emotion eliciting challenge, as well as global ratings of the child's negative affect and basal cortisol levels. The addition of covariates within the latent profile model suggested that children with more violence in the home and children who used less caregiver-oriented regulation strategies were more likely to exhibit a pattern of high cortisol reactivity with moderate signs of distress rather than the average stress response, suggesting possible patterns of adaptation in violent households.

Stress, cortisol and well-being of caregivers and children in home-based child care: a case for differential susceptibility

BACKGROUND

We examined whether children cared for by stressed caregivers show lower socio-emotional well-being and more stress, compared with children cared for by less stressed caregivers.

METHODS

Perceived stress and cortisol levels of professional caregivers (n = 44), and associations with children's (n = 44) well-being and cortisol levels in home-based child care were examined.

RESULTS

Caregiver perceived stress and cortisol levels were related to children's well-being but not to children's cortisol levels. Children's social fearfulness acted as a moderator between caregivers' mean ratio of diurnal change in cortisol and children's well-being. When caregiver cortisol levels decreased, more fearful children were reported higher on well-being than less fearful peers. In contrast, when caregiver cortisol levels increased, more fearful children were reported lower on well-being.

CONCLUSIONS

The findings point to differential susceptibility. Child care organizations and parents need to notice that a non-stressful child care environment is in particular important for children with a difficult temperament.

Allostatic and environmental load in toddlers predicts anxiety in preschool and kindergarten

Psychobiological models of allostatic load have delineated the effects of multiple processes that contribute to risk for psychopathology. This approach has been fruitful, but the interactive contributions of allostatic and environmental load remain understudied in early childhood. Because this developmental period encompasses the emergence of internalizing problems and biological sensitivity to early experiences, this is an important time to examine this process. In two studies, we examined allostatic and environmental load and links to subsequent internalizing and externalizing problems. Study 1 examined relations between load indices and maladjustment, concurrently and at multiple times between age 2 and kindergarten; Study 2 added more comprehensive risk indices in a sample following a group of highly fearful toddlers from 2 to 3 years of age. Results from both studies showed that increased allostatic load related to internalizing problems as environmental risk also increased. Study 2, in addition, showed that fearfulness interacted with allostatic and environmental load indices to predict greater anxiety among the fearful children who had high levels of allostatic and environmental load. Taken together, the findings support a model of risk for internalizing characterized by the interaction of biological and environmental stressors, and demonstrate the importance of considering individual differences and environmental context in applying models of allostatic load to developmental change in early childhood.

Inhibition and exuberance in preschool classrooms: associations with peer social experiences and changes in cortisol across the preschool year

Associations between behavioral inhibition and activity of the hypothalamic-pituitary-adrenocortical (HPA) system, a stress-sensitive neuroendocrine system indexed by salivary cortisol, have varied widely across studies. In the current study, we examined the role of peer social experiences in moderating patterns of association between inhibition/risk-aversion and cortisol reactivity. As expected based on previous research, preschool children (N = 165, 78 boys, 87 girls, 3.0-5.0 years) had significantly different social experiences in their preschool classrooms depending on temperament. Highly inhibited/risk-averse children were less socially integrated, less dominant, and less involved in aggressive encounters than both average and highly exuberant/risk-seeking children, but they were no more likely to be peer rejected. Highly exuberant children were more dominant, exhibited anger more often, and had friendships characterized by higher conflict. Cortisol levels fell from fall to spring for average and highly exuberant children but not for highly inhibited children. Unexpectedly, for highly inhibited children, having friends and being more dominant and popular than other highly inhibited children was associated with increasing cortisol levels over the school year. In contrast, highly exuberant children who were less socially integrated than other highly exuberant children maintained higher cortisol levels. Results indicate that the types of social experiences that affect stress-responsive biological systems may differ markedly for highly inhibited and highly exuberant children.