The moderating role of adrenocortical reactivity in the associations between interparental conflict, emotional reactivity, and school adjustment

This study tested whether the associations between interparental conflict, children's emotional reactivity, and school adjustment were moderated by children's cortisol reactivity in a sample of young children (N = 243; mean age = 4.6 years at Wave 1; 56% female, 44% male) and their parents. Using a longitudinal, autoregressive design, observational assessments of children's emotional reactivity at Wave 2 mediated the relationship between an observational measure of Wave 1 conflict between parents and teacher's report of children's school adjustment at Wave 3. However, children's cortisol reactivity to parent conflict at Wave 1 moderated the first link, such that emotional reactivity operated as a mediator for children with heightened cortisol reactivity but not children with low cortisol reactivity. Moderation was expressed in a "for better" or "for worse" form hypothesized by biological sensitivity to context theory. Thus, children with high cortisol reactivity experienced greater emotional reactivity than their peers when faced with more destructive conflict but also lower emotional reactivity when exposed to more constructive interparental conflict. Results are discussed as to how they advance emotional security and biological sensitivity to context theories.

Adolescents' attachment, quality of relationships with residential caregivers, and emotion regulation

INTRODUCTION

Adolescents in residential care are more likely to report insecure and especially disorganized attachments, which lead to difficulties in emotion regulation and compromise the quality of their interpersonal relationships. In residential care, it is expected that sensitive and responsive caregivers are able to help adolescents regulate their feelings of distress, enabling them to experience a sense of emotional security. The present study sought to analyze the effects of the quality of attachment on emotion regulation and to test the moderating effect of quality of relationship (from adolescents' and caregivers' perspectives) on this association.

METHODS

The sample involved 306 adolescents, 12-18 years of age, living in residential care and 70 caregivers.

RESULTS

The findings underscored the importance of the quality of the relationship with residential caregivers on adolescents' emotion regulation competencies over time. The results also showed that the quality of relationship (emotional closeness) as perceived by the caregivers moderated the association between adolescents' attachment avoidance levels and their emotion regulation strategies.

CONCLUSIONS

The results are discussed according to attachment theory, and underscore the role the relationship with caregivers plays in the affective reorganization of adolescents living in residential care.

A mother's touch: Preschool-aged children are regulated by positive maternal touch

Positive maternal touch plays an important role in the development of children's physiological regulation and cognitive development in infancy, as well as the development of sociality in early childhood. However, few studies have looked beyond infancy to consider the possible continuing impact of positive maternal touch on child stress reactivity during early childhood. A diverse community sample of mothers (N = 114, M_age  = 33.52 years, SD = 5.33) and their preschool-aged children (M_age  = 41.68 months, SD = 4.67; 49.1% female) participated in the study. Basic demographics were reported by mothers. We coded maternal touch behaviors during an emotionally charged laboratory conversation task and assessed children's physiological reactivity to stressful laboratory tasks with salivary cortisol. Results reveal a significant negative association between positive maternal touch and child salivary cortisol reactivity. In addition, family income, adjusted for family size, and child sex were significantly associated with child cortisol stress reactivity. Findings are discussed in terms of persistent downregulating effects of positive maternal touch on child stress reactivity, as well as possible links of stress reactivity with family income, a proxy for economic stress, and child sex.

Parenting Stress During the COVID-19 Outbreak: Socioeconomic and Environmental Risk Factors and Implications for Children Emotion Regulation

The COVID-19 outbreak imposed to Italian families many changes in their daily life increasing the risk of developing psychological problems. The present study explored risk factors associated with parenting stress and implications for children's emotion regulation in families with different socioeconomic risks. Parents of 2-14 years old children completed a survey reporting difficulties experienced due to the lockdown, level of household chaos, parenting stress, parent involvement in the child's daily life, and children emotion regulation competences. The general mean levels of parenting stress and children emotion regulation abilities were not at clinical level compared with Italian norms. Household chaos predicted higher levels of parenting stress, which, in turn, was associated with less effective emotion regulation in children through the mediating role of parental involvement. More stressed parents were less involved in their children's activities, decreasing children's effective emotion regulation. Only for SES no-risk families, the lockdown constraints increased parenting stress. For SES at-risk families, the impact of parenting stress and involvement on children regulation strategies was stronger, with a protective role played by parental involvement on children's negativity not evident for SES no-risk families. Dealing with the lockdown is a stressful experience for parents who have to balance personal life, work, and children upbringing, without other help. This situation potentially impairs their ability to be supportive caregivers and is consequently detrimental for children well-being. Policies should take into consideration the implications of the lockdown for families' mental health and tailor supportive interventions according to family's risk factors.

Elevated infant cortisol is necessary but not sufficient for transmission of environmental risk to infant social development: Cross-species evidence of mother-infant physiological social transmission

Environmental adversity increases child susceptibility to disrupted developmental outcomes, but the mechanisms by which adversity can shape development remain unclear. A translational cross-species approach was used to examine stress-mediated pathways by which poverty-related adversity can influence infant social development. Findings from a longitudinal sample of low-income mother-infant dyads indicated that infant cortisol (CORT) on its own did not mediate relations between early-life scarcity-adversity exposure and later infant behavior in a mother-child interaction task. However, maternal CORT through infant CORT served as a mediating pathway, even when controlling for parenting behavior. Findings using a rodent "scarcity-adversity" model indicated that pharmacologically blocking pup corticosterone (CORT, rodent equivalent to cortisol) in the presence of a stressed mother causally prevented social transmission of scarcity-adversity effects on pup social behavior. Furthermore, pharmacologically increasing pup CORT without the mother present was not sufficient to disrupt pup social behavior. Integration of our cross-species results suggests that elevated infant CORT may be necessary, but without elevated caregiver CORT, may not be sufficient in mediating the effects of environmental adversity on development. These findings underscore the importance of considering infant stress physiology in relation to the broader social context, including caregiver stress physiology, in research and interventional efforts.

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.

Deconstructing Cumulative Risk: Poverty and Aspects of Instability Relate Uniquely to Young Children's Basal Cortisol

This study deconstructs cumulative risk to probe unique relations to basal cortisol for family income and four distinct aspects of poverty-related instability. Participants were 288 children aged 3-5 years who attended Head Start preschool. Parents reported on poverty risks. Children provided samples of salivary cortisol at four times of day on 6 days. Results of hierarchical linear modeling with piecewise latent growth curves representing basal cortisol indicated unique relations for family income, household chaos, neighborhood risk, attachment-disruptive residential changes, and non-attachment changes. The findings support an equifinality implied by cumulative risk models in demonstrating that multiple risks relate to cortisol dysregulation yet also suggest the utility of considering unique effects of different risks for neurophysiological stress response functioning.

Biological sensitivity to context: A test of the hypothesized U-shaped relation between early adversity and stress responsivity

We conducted signal detection analyses to test for curvilinear, U-shaped relations between early experiences of adversity and heightened physiological responses to challenge, as proposed by biological sensitivity to context theory. Based on analysis of an ethnically diverse sample of 338 kindergarten children (4-6 years old) and their families, we identified levels and types of adversity that, singly and interactively, predicted high (top 25%) and low (bottom 25%) rates of stress reactivity. The results offered support for the hypothesized U-shaped curve and conceptually replicated and extended the work of Ellis, Essex, and Boyce (2005). Across both sympathetic and adrenocortical systems, a disproportionate number of children growing up under conditions characterized by either low or high adversity (as indexed by restrictive parenting, family stress, and family economic condition) displayed heightened stress reactivity, compared with peers growing up under conditions of moderate adversity. Finally, as hypothesized by the adaptive calibration model, a disproportionate number of children who experienced exceptionally stressful family conditions displayed blunted cortisol reactivity to stress.

The Relation between Specific Parenting Behaviors and Toddlers' Early Anxious Behaviors is Moderated by Toddler Cortisol Reactivity

Differential susceptibility theory posits that neurobiological reactivity (e.g., cortisol levels) should be considered as an individual index of susceptibility to both positive and negative environments. The current investigation separately examines cortisol reactivity and total concentration in toddlerhood as moderators of the longitudinal relation between maternal protection and encouragement of independence and increases or decreases in observed anxious behaviors, respectively. A total of 119 mother-toddler dyads participated in a laboratory visit when toddlers were 12- to 18-months-old. Mothers reported on their parenting behaviors and toddlers participated in a novelty episode from which their anxious behaviors were coded. Toddlers provided three saliva samples, yielding measures of cortisol reactivity and total cortisol concentration. One year later, dyads returned to the laboratory where toddlers participated in another novelty episode to observationally assess anxious behaviors. Results revealed that maternal protection tended to relate to greater increases in anxious behaviors one year later only for toddlers who displayed high cortisol reactivity. Cortisol reactivity also moderated the relation between maternal encouragement of independence and change in toddler anxious behaviors, with this parenting behavior relating to greater decreases in anxious behaviors only for toddlers with high cortisol reactivity. Results examining total cortisol concentration as a moderator were not significant. Results suggest the importance of considering toddler cortisol reactivity a context of susceptibility when examining the longitudinal relation between parenting behaviors and the development of anxious behaviors in toddlerhood.

Catechol-O-methyltransferase Val158Met Genotype and Early-Life Family Adversity Interactively Affect Attention-Deficit Hyperactivity Symptoms Across Childhood

Attention-deficit hyperactivity disorder (ADHD) is among the most commonly diagnosed psychiatric disorders of childhood. The dopaminergic system has been shown to have substantial effects on its etiology, with both functional Catechol-O-methyltransferase (COMT) Val158Met genotype and early-life environmental adversity involved in the risk of inattention and hyperactivity/impulsivity symptoms. In this prospective longitudinal study, we examined for the first time the impact of proximal and distal early-life family adversity and COMT Val158Met polymorphism gene - both the direct and the interactive effects, on children's ADHD symptoms across childhood. Data came from the Family Life Project, a prospective longitudinal study of 1,292 children and families in high poverty from birth to 11 years. In infancy, data regarding socioeconomic (SES)-risk-factors, observed-caregiving behaviors, and DNA genotyping were collected. In early and middle childhood teachers rated the occurrence and severity of the child's ADHD symptoms. Multilevel growth curve models revealed independent effects of COMT, early-life SES-risk and negative caregiving on ADHD symptoms in early and middle childhood. Significant gene-environment interactions were found, indicating that overall, carriers of at least one COMT158Met allele were more sensitive to early-life adversity, showing higher inattention and hyperactivity/impulsivity symptoms severity in childhood when exposed to high SES-risk factors in infancy, compared to Val-Val carriers. Findings provide new insights into the complex etiology of ADHD and underline the need for further investigation of the neuronal mechanisms underlying gene-environment interactions. Findings might have implications for prevention and intervention strategies with a focus on early-life family relationships in genetically at-risk children.

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.

Disentangling levels of mother-infant neuroendocrine attunement and longitudinal relations with maternal risk and protective factors

Scientific understanding of mother-infant HPA axis attunement has been limited by discrepant methods for assessing attunement that often conflate different levels of association. We sought to refine the conceptualization of attunement by investigating whether mother-infant cortisol attunement exists as coupling of response trajectories within an acute stress episode, separate from shared developmental patterns and/or overall dyadic similarity in cortisol levels, and whether the degree of attunement depends on within- or between-dyad differences in maternal risk and protective factors. We examined these questions using a longitudinal study with mother/infant salivary cortisol during dyadic stressors at 6, 12, and 18 months postnatal. A three-level hierarchical linear model showed that sample-wide associations between mother and infant cortisol were not significant at any level, suggesting normative lack of attunement; however, there was significant variability in degree of attunement across dyads. Concurrent levels of family resources and social support satisfaction predicted lower mother-infant cortisol attunement within the session, and overall (mean) parenting stress predicted the opposite. Follow-up analyses showed this was typically due to an increase in infants' (but not their mothers') within-session cortisol response slopes with increasing support and decreasing stress. Implications for the role of mother-infant cortisol attunement in intergenerational stress transmission are discussed.

Severe Poverty and Growth in Behavioral Self-Regulation: The Mediating Role of Parenting

This study examined how exposure to severe poverty related to behavioral self-regulation growth during early childhood as mediated by parenting practices. Ethnic differences were tested. Data were collected across 4 waves from 359 low-income African American and Latino families. The frequency of exposure to severe poverty was indicated by how many times family income fell below 50% of the federal poverty line across 4 waves. Behavioral self-regulation was assessed when children were 3½, 6, and 7 years old (Wave 2-4), and parenting was observed when children were age 2½ years old (Wave 1). More frequent exposure to severe poverty was associated with slower behavioral self-regulation growth, and the effect was partially mediated through less sensitive and supportive parenting practices for Latino families. The mediation was not observed for African American families. Targeting the promotion of sensitive and supportive parenting practices may be an effective strategy for accelerating self-regulation development.

Demographic and psychosocial factors associated with hair cortisol concentrations in preschool children

BACKGROUND

Early life stress has enduring effects on physical and mental health. Hair cortisol concentrations (HCCs) reflect exposures to contextual stressors in early life, but are understudied in preschool children.

METHODS

Hair samples from children (N = 693) during clinic visits (CVs) scheduled at 1-4 years (CV1-CV4) were measured using validated assay methods for HCC.

RESULTS

HCCs were highest at CV1 and decreased at CV2-CV4, with no sex differences. Black children had higher HCC than White/other children; these differences persisted even after adjusting for socioeconomic factors. Bivariable analyses showed significant effects on HCC for Black race, with specific demographic and psychosocial factors at different ages. Multivariable analyses showed that higher HCC at CV1 were associated with Black race and male sex; at CV2 with Black race, lower maternal self-esteem, socioeconomic adversity, and the child's risk for developmental delay; at CV3 with Black race; at CV4 with maternal depression and the child's prior HCC values.

CONCLUSIONS

HCCs were higher in Black children than White/other races; differences were related to maternal factors, socioeconomic adversity, and the child's risk for developmental delay. Public health measures to reduce disparities between Blacks and other races must also consider the long-term effects of chronic stress in early life.

Unpredictable maternal behavior is associated with a blunted infant cortisol response

BACKGROUND

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is associated with poor physical and mental health. Early-life adversity may dysregulate cortisol response to subsequent stress. This study examines the association between patterns of maternal behavior and infant stress response to a challenge. Specifically, we test whether infant exposure to unpredictable maternal sensory signals is related to the cortisol response to a painful stressor.

METHOD

Participants were 102 mothers and their children enrolled in a longitudinal study. Patterns of maternal sensory signals were evaluated at 6 and 12 months during a 10-min mother-infant play episode. Entropy rate was calculated as a quantitative measure of the degree of unpredictability of maternal sensory signals (visual, auditory, and tactile) exhibited during the play episode. Infant saliva samples were collected for cortisol analysis before and after inoculation at 12 months.

RESULTS

Unpredictable patterns of maternal sensory signals were associated with a blunted infant cortisol response to a painful stressor. This relation persisted after evaluation of covariates including maternal sensitivity and maternal psychological distress.

CONCLUSIONS

This study provides evidence that unpredictable patterns of maternal sensory signals are one process through which caregiving affects the function of infant stress response systems.

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.

Interrelatedness of Children's Psychological and Physiological Responses to Interparental Conflict: A Moderating Role of Harsh Parenting

Children's psychological and physiological responses to interparental conflict have received considerable attention due to their implications for later adjustment, yet limited research has investigated the interplay between these two response systems. This study investigates patterns of association between children's psychological responses (e.g., emotional distress) and cortisol reactivity to interparental conflict, including possible moderations by negative caregiving environment. Participants included 193 families (mother, father, and child). Parents completed questionnaires relating to their caregiving behaviors toward the child (107 girls and 86 boys, M age = 7.99 years, SD = 0.53 years) and children's psychological responses to interparental conflict. Children provided three saliva samples over the course of watching videos depicting conflicts between two adults, whom children were asked to pretend were their parents. Based on a series of Latent Growth Curve Models, only children's emotional responses to interparental conflict (indicated by increased distress) were associated with greater cortisol reactivity. Additionally, fathers' harsh parenting behavior moderated the relation between children's emotional reactivity and cortisol reactivity, yet the moderation effect was not found for mothers' parenting. Findings are discussed in terms of the importance of exploring both psychological and physiological reactivity to conflict and the possible moderating role of harsh parenting.

Maternal prenatal and early postnatal distress and child stress responses at age 6

Individuals differ in their physiological and behavioral stress responses. Alterations in these responses have been associated with mental and physical health. Therefore, it is important to understand how stress responses develop. This study investigated whether in a healthy, non-risk population, 6-year-old's physiological (cortisol) and behavioral (gazing) stress responses were associated with stress early in the child's life, in the form of maternal prenatal and early postnatal distress. Additionally, associations between the two stress responses were studied. At age 6, children (n = 149; M_age = 6.09; 70 girls) in a longitudinal project that started prenatally (n = 193), participated in a social evaluative stress test (Children's Reactions to Evaluation Stress Test, CREST) in front of a judge. To operationalize physiological stress responses six cortisol saliva samples were collected and cortisol stress reactivity and total stress cortisol scores were calculated. To operationalize behavioral stress responses, gazing at the judge during the stress test was observed. Maternal prenatal distress (week 37) was measured using questionnaires and physiological measures, that is, cortisol saliva samples. Early postnatal maternal distress (first 6 months) was measured using questionnaires. Results of hierarchical regression analyses indicated that less maternal prenatal fear of giving birth, higher maternal prenatal evening cortisol concentrations, and more maternal feelings of anxiety in the first 6 postnatal months were all uniquely associated with higher total stress cortisol concentrations in children at age 6. Additionally, correlations indicated that children with higher cortisol stress reactivity gazed less in the direction of the judge. Results indicate that maternal prenatal and early postnatal distress are associated with children's later hypothalamic-pituitary-adrenal-axis functioning and that in children gazing and physiological stress reactivity are related. Lay summary We examined whether maternal stress and anxiety during pregnancy, as measured by means of maternal self-reports and saliva cortisol samples, as well as maternal stress and anxiety in the first 6 months of the child's life, measured using maternal self-reports, were associated with children's physiological (cortisol) and behavioral (gazing) responses during a stressful laboratory situation at the age of 6. Results showed that mothers with higher levels of distress in late pregnancy and/or the early postnatal period had children with higher cortisol concentrations during the stressful situation. This suggests that maternal prenatal and early postnatal distress are associated with children's later hypothalamic-pituitary-adrenal-axis functioning.

Improving infants' stress-induced cortisol regulation through attachment-based intervention: A randomized controlled trial

Attachment-based parenting interventions have shown positive effects on early cortisol regulation, a key biomarker. Evaluations to date have focused on diurnal cortisol production in high-risk infants. It is important to understand whether attachment-based intervention may also improve stress-induced cortisol production in typically developing infants. This randomized controlled trial tested an enhanced model of U.S. Early Head Start (EHS) services that combined home-based EHS with a brief, attachment-based parenting intervention, Attachment and Biobehavioral Catch-up (ABC). The trial included 153 low-income mothers and their infants (M age 12.4 months [SD = 4.1]). Control participants received home-based EHS plus 10 weekly books. Intent-to-treat analyses using multilevel models revealed a significant indirect intervention effect on infants' rates of cortisol change in response to a series of mild stressors. The intervention increased maternal sensitivity, which in turn improved cortisol regulation, particularly infants' rates of cortisol recovery. The findings illustrate the efficacy of EHS plus ABC for supporting infants' stress-induced cortisol regulation and implicate sensitive maternal behavior as the underlying driver of the intervention effect. Findings are discussed in terms of the preventative value of attachment-based parenting interventions that improve both parenting and infants' physiological regulation.

Socioeconomic risk moderates the association between caregiver cortisol levels and infant cortisol reactivity to emotion induction at 24 months

Relations between maternal baseline cortisol and infant cortisol reactivity to an emotion induction procedure at child ages 7, 15, and 24 months were analyzed using data from the Family Life Project (N = 1,292). The emotion induction consisted of a series of standardized and validated tasks, including an arm restraint, toy removal, and mask presentation, intended to elicit responses of fear and frustration. Results revealed that at 7 and 15 months, maternal baseline cortisol was negatively related to child cortisol reactivity, such that children of mothers with lower cortisol exhibited steeper cortisol increases in response to the emotion induction. At 24 months, the association between mother and infant cortisol was moderated by socioeconomic risk, such that maternal baseline cortisol was associated with child cortisol reactivity only in dyads characterized by low socioeconomic risk. Furthermore, at 24 months, children of mothers with low baseline cortisol and low socioeconomic risk exhibited decreasing cortisol responses, whereas children of mothers with low baseline cortisol but high risk exhibited flat cortisol responses. Children in dyads characterized by high baseline maternal cortisol also exhibited flat cortisol responses regardless of socioeconomic risk. The role of caregiver physiology in the regulation of the child's stress response in the context of adversity is discussed.

Parenting Skills and Early Childhood Development: Production Function Estimates from Longitudinal Data

We provide evidence on the importance of specific inputs for child cognitive skills by estimating alternative specifications of the early childhood production function, between birth and kindergarten. We identify a new input measure, parent-child interaction, which is both important for development and amenable to policy intervention because parenting skills can be taught. We find that the application of reading books and singing songs and sensitive and engaging parent-child interactions as early as 9 months of age have an important effect on reading among kindergarten children.

Parenting and Cortisol in Infancy Interactively Predict Conduct Problems and Callous-Unemotional Behaviors in Childhood

This study examines observed maternal sensitivity, harsh-intrusion, and mental-state talk in infancy as predictors of conduct problems (CP) and callous-unemotional (CU) behaviors in middle childhood, as well as the extent to which infants' resting cortisol and cortisol reactivity moderate these associations. Using data from the Family Life Project (n = 1,292), results indicate that maternal sensitivity at 6 months predicts fewer CP at first grade, but only for infants who demonstrate high levels of cortisol reactivity. Maternal harsh intrusion predicts fewer empathic-prosocial behaviors, a component of CU behaviors, but only for infants who demonstrate high resting cortisol. Findings are discussed in the context of diathesis-stress and differential susceptibility models.

Developing a neurobehavioral animal model of poverty: Drawing cross-species connections between environments of scarcity-adversity, parenting quality, and infant outcome

Children reared in impoverished environments are at risk for enduring psychological and physical health problems. Mechanisms by which poverty affects development, however, remain unclear. To explore one potential mechanism of poverty's impact on social-emotional and cognitive development, an experimental examination of a rodent model of scarcity-adversity was conducted and compared to results from a longitudinal study of human infants and families followed from birth (N = 1,292) who faced high levels of poverty-related scarcity-adversity. Cross-species results supported the hypothesis that altered caregiving is one pathway by which poverty adversely impacts development. Rodent mothers assigned to the scarcity-adversity condition exhibited decreased sensitive parenting and increased negative parenting relative to mothers assigned to the control condition. Furthermore, scarcity-adversity reared pups exhibited decreased developmental competence as indicated by disrupted nipple attachment, distress vocalization when in physical contact with an anesthetized mother, and reduced preference for maternal odor with corresponding changes in brain activation. Human results indicated that scarcity-adversity was inversely correlated with sensitive parenting and positively correlated with negative parenting, and that parenting fully mediated the association of poverty-related risk with infant indicators of developmental competence. Findings are discussed from the perspective of the usefulness of bidirectional-translational research to inform interventions for at-risk families.

A state-trait model of cortisol in early childhood: Contextual and parental predictors of stable and time-varying effects

This study examined state-trait models of diurnal cortisol (morning level and diurnal slope), and whether income, cumulative risk and parenting behaviors predicted variance in trait and state levels of cortisol. The sample of 306 mothers and their preschool children included 29% families at or near poverty, 27% families below the median income, and the remaining families at middle and upper income. Diurnal cortisol, income, cumulative risk, and parenting were measured at 4 time points, once every 9months, starting when children were 36-40months. State-trait models fit the data, suggesting significant state but not trait variance in cortisol. Low income and cumulative risk were related to trait levels of diurnal cortisol with little evidence of time-varying or state effects. Stable levels of parenting predicted trait levels of diurnal cortisol and time-varying levels of parenting predicted time-varying state levels of diurnal cortisol. Findings highlight the allostatic process of adaptation to risk as well as time-specific reactivity to variability in experience.

Healthy Foundations Study: a randomised controlled trial to evaluate biological embedding of early-life experiences

INTRODUCTION

Adverse early experiences are associated with long-lasting disruptions in physiology, development and health. These experiences may be 'biologically embedded' into molecular and genomic systems that determine later expressions of vulnerability. Most studies to date have not examined whether preventive interventions can potentially reverse biological embedding. The Nurse-Family Partnership (NFP) is an evidence-based intervention with demonstrated efficacy in improving prenatal health, parenting and child functioning. The Healthy Foundations Study is an innovative birth cohort which will evaluate the impact of the NFP on biological outcomes of mothers and their infants.

METHODS AND ANALYSIS

Starting in 2013, up to 400 pregnant mothers and their newborns were recruited from the British Columbia Healthy Connections Project-a randomised controlled trial of the NFP, and will be followed to child aged 2 years. Women were recruited prior to 28 weeks' gestation and then individually randomised to receive existing services (comparison group) or NFP plus existing services (intervention group). Hair samples are collected from mothers at baseline and 2 months post partum to measure physiological stress. Saliva samples are collected from infants during all visits for analyses of stress and immune function. Buccal swabs are collected from infants at 2 and 24 months to assess DNA methylation. Biological samples will be related to child outcome measures at age 2 years.

ETHICS AND DISSEMINATION

The study received ethical approval from seven research ethics boards. Findings from this study will be shared broadly with the research community through peer-reviewed publications, and conference presentations, as well as seminars with our policy partners and relevant healthcare providers. The outcomes of this study will provide all stakeholders with important information regarding how early adversity may lead to health and behavioural disparities and how these may be altered through early interventions.

TRIAL REGISTRATION NUMBER

NCT01672060; Pre-results.

Salivary cortisol reactivity in preschoolers is associated with hair cortisol and behavioral problems

The interplay between children's cortisol reactivity to challenge and cumulative cortisol exposure is not well understood. Examining the role of cortisol reactivity in early childhood may elucidate biological mechanisms that contribute to children's chronic physiological stress and behavioral dysregulation. In a sample of 65 preschool-aged children, we examined the relation between children's salivary cortisol reactivity to challenging tasks and their hair cortisol concentration (HCC). While both are biomarkers of the hypothalamic-pituitary-adrenal (HPA) axis, salivary cortisol reactivity reflects an acute cortisol response to a stressor and HCC reflects cumulative cortisol exposure. In addition, we examined the relations of these stress biomarkers with internalizing and externalizing problems. Salivary cortisol reactivity was associated with higher HCC and with increased externalizing behaviors. Child HCC also was positively correlated with parent HCC. Results highlight the contributions of salivary cortisol reactivity to children's cumulative cortisol exposure, which may add to their biological risk for health problems later. The observed association between externalizing problems and salivary cortisol reactivity indicates concordances between dysregulated behavioral reactions and dysregulated cortisol responses to challenges. The finding that salivary cortisol reactivity to challenge in early childhood plays a role in children's cumulative cortisol exposure and behavioral development suggests pathways through which cortisol reactivity may influence long-term physical and mental health.

Exploring longitudinal associations between neighborhood disadvantage and cortisol levels in early childhood

Children who grow up in poverty are more likely to experience chronic stressors that generate "wear" on stress regulatory systems including the hypothalamus-pituitary-adrenal (HPA) axis. This can have long-term consequences for health and well-being. Prior research has examined the role of proximal family and home contributions to HPA axis functioning. However, there is evidence to suggest that more distal levels of context, including neighborhoods, also matter. Prior evidence has primarily focused on adolescents and adults, with little evidence linking the neighborhood context with HPA activity in infancy and toddlerhood. We tested whether neighborhood disadvantage (indexed by US Census data) was associated with basal salivary cortisol levels at 7, 15, and 24 months of child age in a large sample of families (N = 1,292) residing in predominately low-income and rural communities in the United States. Multilevel models indicated that neighborhood disadvantage was positively associated with salivary cortisol levels and that this effect emerged across time. This effect was moderated by the race/ethnicity of children such that the association was only observed in White children in our sample. Findings provide preliminary evidence that the neighborhood context is associated with stress regulation during toddlerhood, elucidating a need for future work to address possible mechanisms.

Circle of Security-Parenting: A randomized controlled trial in Head Start

Although evidence shows that attachment insecurity and disorganization increase risk for the development of psychopathology (Fearon, Bakermans-Kranenburg, van IJzendoorn, Lapsley, & Roisman, 2010; Groh, Roisman, van IJzendoorn, Bakermans-Kranenburg, & Fearon, 2012), implementation challenges have precluded dissemination of attachment interventions on the broad scale at which they are needed. The Circle of Security-Parenting Intervention (COS-P; Cooper, Hoffman, & Powell, 2009), designed with broad implementation in mind, addresses this gap by training community service providers to use a manualized, video-based program to help caregivers provide a secure base and a safe haven for their children. The present study is a randomized controlled trial of COS-P in a low-income sample of Head Start enrolled children and their mothers. Mothers (N = 141; 75 intervention, 66 waitlist control) completed a baseline assessment and returned with their children after the 10-week intervention for the outcome assessment, which included the Strange Situation. Intent to treat analyses revealed a main effect for maternal response to child distress, with mothers assigned to COS-P reporting fewer unsupportive (but not more supportive) responses to distress than control group mothers, and a main effect for one dimension of child executive functioning (inhibitory control but not cognitive flexibility when maternal age and marital status were controlled), with intervention group children showing greater control. There were, however, no main effects of intervention for child attachment or behavior problems. Exploratory follow-up analyses suggested intervention effects were moderated by maternal attachment style or depressive symptoms, with moderated intervention effects emerging for child attachment security and disorganization, but not avoidance; for inhibitory control but not cognitive flexibility; and for child internalizing but not externalizing behavior problems. This initial randomized controlled trial of the efficacy of COS-P sets the stage for further exploration of "what works for whom" in attachment intervention.

Individual differences in the activity of the hypothalamic pituitary adrenal axis: Relations to age and cumulative risk in early childhood

This study examined individual differences in the function of the hypothalamic-pituitary-adrenal (HPA) axis with regard to age and cumulative risk during challenging laboratory tasks administered at 6, 12, 24, and 36 months. Saliva samples were collected from a majority-minority sample of N=185 children (57% African American, 50% female) prior to and following these tasks and later assayed for cortisol. Cumulative distal risk was indexed via a composite of maternal marital status, maternal education, income-to-needs ratio, the number of children in the household, and maternal age at childbirth. Probing of hierarchical models in which cortisol levels and age were nested within child revealed significant differences in cortisol as a function of both age and cumulative risk, such that children exposed to high levels of risk exhibited higher levels of cortisol both within and across age. These results highlight the sensitivity of the HPA axis to environmental context at the level of the individual, even as that sensitivity is manifest against the background of species-typical biological development.

Moderate within-person variability in cortisol is related to executive function in early childhood

Lab-based experimental studies with humans and in animal models demonstrate that the relation between glucocorticoid (GC) levels and performance on measures of higher-order cognitive ability such as executive function (EF) is best described by an inverted U-shape curve. Moderate levels of GCs (cortisol/corticosterone) are associated with comparatively better performance relative to GC levels that are particularly high or low. Although findings from experimental studies are definitive and have high internal validity, the external validity of this association as an aspect of children's development is unknown. Here we analyze data from the Family Life Project (N=1292), a prospective longitudinal sample of children and families in predominantly low-income and rural communities followed longitudinally from infancy through age 60 months. Consistent with the prior experimental literature, we found evidence of an inverted-U relation. For children with relatively low cortisol levels, on average, between the ages 7, 15, 24, and 48 months, those illustrating moderate fluctuations in their cortisol levels over this span tended to show subsequently better EF performance at 60 months, than did children with either highly stable or highly variable temporal profiles. This curvilinear function did not extend to children whose cortisol levels were high, on average. These children tended to show lower EF performance, irrespective the stability of their cortisol levels over time.

Measuring Stress in Young Children Using Hair Cortisol: The State of the Science

Extensive literature suggests that adverse experiences in early childhood may deleteriously impact later health. These effects are thought to be related to the impact of persistent or chronic stress on various biological processes, mediated by dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, and ultimately irregularities in cortisol levels. Ameliorating persistent stress in young children requires accurately measuring the chronicity of physiologic stress, which is difficult in young children because of unreliable self-report and the burden and inaccuracy associated with using invasive acute-stress biomeasures. A better way to approximate persistent stress in young children is measuring hair cortisol concentration (HCC), as it only requires one noninvasive collection to measure months of HPA-axis activity or experienced stress. However, few studies measure HCC in young children despite wide use in adult stress research. This article reviews and synthesizes research that uses HCC to approximate persistent stress in healthy children, 12-60 months of age. Reviewed studies indicate that HCC is elevated in young children who are experiencing forms of persistent stress such as low socioeconomic status and maternal distress. Hair cortisol is thus a promising measure of early childhood persistent stress, but due to the limited use of HCC in this population, much research is still needed. Specifically, nurse researchers may need to measure several factors associated with early childhood persistent stress and HCC to identify which children are at risk for stress-related disease.

Biological embedding of perinatal social relationships in infant stress reactivity

Whereas significant advances have been made in understanding how exposure to early adversity "gets under the skin" of children to result in long term changes in developmental outcomes, the processes by which positive social relationships become biologically embedded remain poorly understood. The aim of this study was to understand the pathways by which maternal and infant social environments become biologically embedded in infant cortisol reactivity. Two hundred seventy-two pregnant women and their infants were prospectively assessed during pregnancy and at 6 months postpartum. In serial mediation analyses, higher perceived social support from partners during pregnancy was associated with lower infant cortisol reactivity or larger decreases in cortisol in response to a stressor at 6 months of age via lower self-reported prenatal maternal depression and higher mother-infant interaction quality. The findings add to our understanding of how perinatal social relationships become biologically embedded in child development.

Dimensions of Maternal Parenting and Infants' Autonomic Functioning Interactively Predict Early Internalizing Behavior Problems

Developmental pathways to childhood internalizing behavior problems are complex, with both environmental and child-level factors contributing to their emergence. The authors use data from a prospective longitudinal study (n = 206) to examine the associations between dimensions of caregiving experiences in the first year of life and anxious/depressed and withdrawn behaviors in early childhood. Additionally, the authors examine the extent to which these associations were moderated by infants' autonomic functioning in the first year of life indexed using measures of respiratory sinus arrhythmia (RSA) and heart period (HP). Findings suggest that higher levels of maternal sensitivity in infancy are associated with fewer anxious/depressed and withdrawn behaviors at age 3 years. Negative intrusiveness was found to be positively associated with children's anxious/depressed behaviors but not withdrawn behaviors. Further, moderation analyses suggested that the link between negative intrusive parenting during infancy and subsequent anxious/depressed behaviors is exacerbated for infants with average or low baseline HP and that positive engaging parenting during infancy was negatively related to withdrawn behaviors for infants demonstrating average to high levels baseline HP. Interestingly, RSA was not found to moderate the associations between parenting in infancy and later internalizing behavior problems suggesting that, during infancy, overall autonomic functioning may have greater implications for the development of internalizing behaviors than do parasympathetic influences alone. Implications of these findings and future directions for research are discussed.

The role of anxiety in cortisol stress response and cortisol recovery in boys with oppositional defiant disorder/conduct disorder

Children with antisocial and aggressive behaviors have been found to show abnormal neurobiological responses to stress, specifically impaired cortisol stress reactivity. The role of individual characteristics, such as comorbid anxiety, in the stress response is far less studied. Furthermore, this study extended previous studies in that not only baseline and reactivity to a psychosocial stressor were examined, but also recovery from a stressor. These three phases of cortisol could be impacted differentially in boys with oppositional defiant disorder/conduct disorder (ODD/CD) with (+ANX) and without anxiety (-ANX). The results revealed that cortisol patterns in response to psychosocial stress were different for boys with ODD/CD+ANX (n=32), ODD/CD-ANX (n=22) and non-clinical controls (NC) (n=34), with age range of 7.8-12.9 years. The ODD/CD-ANX group showed lower overall cortisol levels than the NC group. When considering the three phases of cortisol separately, the ODD/CD-ANX group had lower baseline cortisol levels relative to the other groups, whereas the ODD/CD+ANX showed an impaired cortisol recovery response. Within those with ODD/CD, callous-unemotional traits were predictive of high baseline cortisol levels. Also, anxiety predicted high baseline and recovery cortisol levels, whereas a high number of CD symptoms predicted reduced cortisol stress reactivity. These results clearly indicate that comorbid anxiety is an important factor in explaining differences in stress response profiles in boys with ODD/CD; although boys with CD/ODD are generally characterized by an impaired cortisol stress response, we found that those with comorbid anxiety showed impaired cortisol recovery, whereas those without anxiety showed reduced baseline cortisol levels.

Understanding the unfolding of stress regulation in infants

Early identification of problems with psychosocial stress regulation is important for supporting mental and physical health. However, we currently lack knowledge about when reliable individual differences in stress-responsive physiology emerge and which aspects of maternal behavior determine the unfolding of infants' stress responses. Knowledge of these processes is further limited by analytic approaches that do not account for multiple levels of within- and between-family effects. In a low-risk sample (n = 100 dyads), we observed infant cortisol and mother/infant behavior during regular play and stress sessions longitudinally from age 1 to 3, and used a three-level model to separately examine variability in infant cortisol trajectories within sessions, across years, and across infants. Stable individual differences in hypothalamus-pituitary-adrenal axis regulation were observed in the first 3 years of life. Infants of less sensitive and more intrusive mothers manifested stress sensitization, that is, elevated cortisol levels during and following stress exposure, a profile related to behavioral distress. These findings have important practical implications, suggesting that children at risk for long-term stress dysregulation may be identified in the earliest years of life.

Daily stressor reactivity during adolescence: The buffering role of parental warmth

OBJECTIVE

This study examined youth stressor reactivity in the form of links between daily stressors and adolescents' negative affect, physical health symptoms, and cortisol patterns. We also tested whether youth gender and parental warmth moderated these linkages.

METHOD

Participants were the children of employees in the information technology division of a large company (N = 132, mean age = 13.39 years, 55% female). Youth completed daily diary telephone interviews on 8 consecutive evenings and provided saliva samples at 4 time points over 4 days to assess daily stressors and youth physiological and affective functioning. Parental warmth was assessed during in-home interviews. Multilevel modeling was used to account for interdependencies in the data.

RESULTS

Youth who experienced more daily stressors, on average, reported more negative affect and physical health symptoms, on average. Furthermore, on days youth reported more stressors than usual (compared to their own across-day average), they also exhibited more physical health symptoms, reduced evening cortisol decline (e.g., flatter slopes), higher bedtime cortisol, and more negative affect. Girls had stronger within-person linkages between daily stressors and daily negative affect than boys. Parental warmth moderated these within-person linkages: Youth who experienced more parental warmth had lower negative affect and steeper cortisol decline than usual on less stressful days. However, youth who experienced less parental warmth had higher negative affect and their cortisol levels declined less, even on days with lower-than-usual stress.

CONCLUSIONS

Daily stressors are associated with youth's affective and physiological functioning, but parental warmth can support youth's stress recovery. (PsycINFO Database Record

The interplay among socioeconomic status, household chaos, and parenting in the prediction of child conduct problems and callous-unemotional behaviors

Child conduct problems (CP) reflect a heterogeneous collection of oppositional, aggressive, norm-violating, and sometimes violent behaviors, whereas child callous-unemotional (CU) behaviors reflect interpersonal styles of interactions reflecting a lack of guilt and empathy as well as uncaring and shallow emotional responses to others. Taken together, high levels of child CP and CU behaviors are thought to identify a relatively homogenous group of children at elevated risk for persistent and more severe problem behaviors across childhood and into adulthood. Although a large body of research has examined the developmental etiology of CP behaviors, only recently has a developmental psychopathology approach been applied to early CU behaviors. The current study examines multiple levels of contextual influences during the first years of life, including family socioeconomic status, household chaos, and parenting behaviors, on CP and CU behaviors assessed during the first-grade year. Whereas previous studies found associations between parenting behaviors and child problem behaviors moderated by household chaos, the current study found no evidence of moderation. However, path analyses suggest that the associations between child CP and CU behaviors and the contextual variables of socioeconomic status (family income and parental education) and household chaos (disorganization and instability) were mediated by maternal sensitive and harsh-intrusive parenting behavior. Analyses are presented, interpreted, and discussed with respect to both bioecological and family stress models of development.

Stress Physiology in Infancy and Early Childhood: Cortisol Flexibility, Attunement and Coordination

Research on stress physiology in infancy has assumed increasing importance due to its lifelong implications. In this review, we focus on measurement of hypothalamic-pituitary-adrenal (HPA) function, in particular, and on complementary autonomic processes. We suggest that the measure of HPA function has been overly exclusive, focusing on individual reactivity to single, pragmatically selected laboratory challenges. We advocate use of multiple, strategically chosen challenges and within-subject designs. By administering one challenge that typically does not provoke reactivity and another that does, it is possible to represent allostatic load in terms of "flexibility," the capacity to titrate response to challenge. We also recommend assessing infant reactivity in the context of the primary caregiver's physiological function. Infant-mother "attunement" is central to developmental psychology, permeating diverse developmental domains with varied consequences. A review of adrenocortical attunement suggests that attunement is a reliable process, manifest across varied populations. However, attunement appears stronger in the context of more highly stressful circumstances, such that administration of multiple, selected challenges may help evaluate the degree to which individuals titrate attunement to challenge and determine the correlates of this differential attunement. Finally, we advocate studying the "coordination" of HPA function with other aspects of stress physiology and variation in the degree of this coordination. The use of multiple stressors is important here because each stress system is differentially sensitive to different types of challenge. Therefore, use of single stressors in between-subject designs impedes full recognition of the role played by each system. Overall, we recommend measure of flexibility, attunement, and coordination in the context of multiple challenges to capture allostasis in environmental and physiological context. The simultaneous use of such inclusive and integrative metrics may yield more reliable findings than has hitherto been the case. The interrelation of these metrics can be understood in the context of the adaptive calibration model..

Maternal depression across the first years of life compromises child psychosocial adjustment; relations to child HPA-axis functioning

Maternal depression across the first years of life negatively impacts children's development. One pathway of vulnerability may involve functioning of the hypothalamic-pituitary-adrenal (HPA) axis. We utilize a community cohort of 1983 women with no comorbid risk repeatedly assessed for depression from birth to six years to form two groups; chronically depressed (N=40) and non-depressed (N=91) women. At six years, mother and child underwent psychiatric diagnosis, child salivary cortisol (CT) was assessed three times during a home-visit, mother-child interaction was videotaped, and child empathy was coded from behavioral paradigms. Latent Growth curve Model using Structural Equation Modeling (SEM) estimated the links between maternal depression and mother's negative parenting and three child outcomes; psychopathology, social withdrawal, and empathy as related to child CT baseline and variability. Depressed mothers displayed more negative parenting and their children showed more Axis-I psychopathology and social withdrawal. SEM analysis revealed that maternal depression was associated with reduced CT variability, which predicted higher child psychopathology and social withdrawal. Whereas all children exhibited similar initial levels of CT, children of controls reduced CT levels over time while children of depressed mothers maintained high, non-flexible levels. Mother negativity was related to lower initial CT levels, which predicted decreased empathy. Findings suggest that chronic maternal depression may compromise children's social-emotional adjustment by diminishing HPA-system flexibility as well as limiting the mother's capacity to provide attuned and predictable caregiving.

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.

Infant adrenocortical reactivity and behavioral functioning: relation to early exposure to maternal intimate partner violence

Prenatal stress negatively affects fetal development, which in turn may affect infant hypothalamic-pituitary-adrenal (HPA) axis regulation and behavioral functioning. We examined effects of exposure to a traumatic stressor in families [intimate partner violence (IPV)] on both infants' HPA axis reactivity to stress and their internalizing and externalizing behaviors. Infants (n = 182, 50% girls, x age = 11.77 months) were exposed to a laboratory challenge task designed to induce frustration and anger (i.e. arm restraint). Saliva samples were taken pre-task and 20 and 40 min post-task and then assayed for cortisol. Mothers reported on their pregnancy and postpartum IPV history, current mental health, substance use and their infants' behaviors. Structural equation modeling revealed that prenatal, but not postnatal, IPV was independently associated with infant cortisol reactivity and problem behavior. Maternal mental health predicted infant behavioral functioning but not infant HPA axis reactivity. These findings are consistent with the prenatal programing hypothesis; that is, early life stress affects later risk and vulnerability for altered physiological and behavioral regulation.