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

Patterns of stress-related change in salivary alpha-amylase and cortisol among young children: Associations with maternal psychosocial risk factors

Our understanding of associations between family-level risk factors and children's stress physiology is largely derived from studies that apply "mean-based" rather than "person-level" approaches. In this study, we employed group-based trajectory modeling, a person-centered approach, to identify children with similar patterns of stress-related sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis activation, and explored associations between these patterns and maternal psychosocial risk. Participants were five-year-old children (N=147; 52 % female; 62 % Black/African American) and their mothers. Children's saliva was sampled four times during a series of emotional stressor tasks and later assayed for sAA and cortisol, indexing SNS and HPA activity, respectively. Mothers reported their depressive and anxiety symptoms, parenting stress, financial stress, and income. Results revealed two task-related patterns of change for sAA (Low-Stable vs. High-Increasing) and cortisol (Low-Stable vs. High-Decreasing) concentrations. Children from families with lower income were more likely to exhibit the High-Increasing SNS pattern, [OR=0.78, 95 % CI (0.64, 0.95)], and children of mothers reporting more anxiety symptoms [OR=1.06, 95 % CI (1.00, 1.12)] and more parenting stress [OR=1.04, 95 % CI (1.00, 1.07)] were more likely to show the High-Decreasing HPA pattern. Implications of this person-centered approach and findings for advancing our understanding of associations between family-level risk factors and children's stress physiology are discussed.

Reconsidering the nature of threat in infancy: Integrating animal and human studies on neurobiological effects of infant stress

Early life stress has been associated with elevated risk for later psychopathology. One mechanism that may contribute to such long-term risk is alterations in amygdala development, a brain region critical to stress responsivity. Yet effects of stress on the amygdala during human infancy, a period of particularly rapid brain development, remain largely unstudied. In order to model how early stressors may affect infant amygdala development, several discrepancies across the existing literatures on early life stress among rodents and early threat versus deprivation among older human children and adults need to be reconciled. We briefly review the key findings of each of these literatures. We then consider them in light of emerging findings from studies of human infants regarding relations among maternal caregiving, infant cortisol response, and infant amygdala volume. Finally, we advance a developmental salience model of how early threat may impact the rapidly developing infant brain, a model with the potential to integrate across these divergent literatures. Future work to assess the value of this model is also proposed.

Integrating Biobehavioral and Environmental Components of Developmental Psychopathology via Interpersonal Dynamics: An RDoC-Advancing Model

Although the Research Diagnostic Criteria (RDoC) framework proposes biological and environmental mechanisms intersect in the etiology of psychopathology, there is no guidance on how to define or measure experiences in the environment within the RDoC matrix. Interpersonal dynamics during caregiver-child interactions involve temporal coordination of interacting partners' biobehavioral functioning; repeated experiences of signaling to caregivers and responding to caregivers' signals shape children's subsequent socioemotional and brain development. We begin with a review of the extant literature on caregiver-child dynamics, which reveals that RDoC's units of analysis (brain circuits, physiology, behavior, and self-report) are inextricably linked with moment-to-moment changes in the caregiving environment. We then offer a proof-of-concept for integrating biobehavioral RDoC units and environmental components via caregiver-child dynamics. Our approach uses dynamic structural equation models to estimate within-dyad dynamics involving arousal, social, cognitive, and negative or positive affective processes based on second-by-second changes in parasympathetic activity (RSA) during a conflict discussion and a positive event-planning task. Our results illustrate variation in parent-child RSA synchrony, suggesting differences depending on the driver (i.e., child- or parent-led) and on the unique and intersecting domains involved (e.g., positive or negative affect valence systems). We conclude with recommendations for conducting robust, methodologically rigorous studies of interpersonal dynamics that advance the RDoC framework and provide a summary of the clinical implications of this research. Examining caregiver-child dynamics during and across multiple dyadic interaction paradigms that differentially elicit key domains of functioning can deepen understanding of how caregiver- and child-led interpersonal dynamics contribute to child psychopathology risk.

Linking maternal disrupted interaction and infant limbic volumes: The role of infant cortisol output

Despite a large animal literature documenting the role of low maternal nurturance and elevated glucocorticoid production on offspring limbic development, these pathways have not yet been assessed during human infancy. Informed by animal models, the present study examined whether 1) maternal disrupted interaction is related to infant cortisol levels, 2) infant cortisol levels are associated with infant limbic volumes, and 3) infant cortisol levels mediate associations between maternal disrupted interaction and infant limbic volumes. Participants included 57 mother-infant dyads. Infant saliva was measured at one time point before and two time points after the Still-Face Paradigm (SFP) at age 4 months. Five aspects of maternal disrupted interaction were coded during the SFP reunion episode. Between 4 and 25 months (M age = 11.74 months, SD = 6.12), under natural sleep, infants completed an MRI. Amygdala and hippocampal volumes were calculated via automated segmentation. Results indicated that 1) maternal disrupted interaction, and specifically disoriented interaction, with the infant was associated with higher infant salivary cortisol (AUCg) levels during the SFP, 2) higher infant AUCg was related to enlarged bilateral amygdala and hippocampal volumes, and 3) infant AUCg mediated the relation between maternal disrupted interaction and infant amygdala and hippocampal volumes. Findings are consistent with controlled animal studies and provide evidence of a link between increased cortisol levels and enlarged limbic volumes in human infants. Results further suggest that established interventions to decrease maternal disrupted interaction could impact both infant cortisol levels and infant limbic volumes.

Distinct trajectories of caregiver-toddler physiological attunement during routine vaccinations

Introduction

Toddlers rely on their caregivers for regulatory support when faced with pain-related distress. The caregiver's ability to support their toddler relies on their capacity to regulate their own distress and respond effectively to the child's need for support. The aim of the current study was to describe patterns of caregiver-toddler physiological co-regulatory patterns, also known as attunement, during routine vaccinations across the second year of life.

Methods

Caregiver-toddler dyads (N = 189) were part of a longitudinal cohort observed at either 12-, 18-, or 24-month well-baby vaccinations. Parallel-process growth-mixture modeling was used to examine patterns of dyadic physiological co-regulatory responses, indexed by high-frequency heart rate variability (HF-HRV).

Results

Three groups of dyads were discerned. The largest group (approximately 80%) demonstrated physiological attunement, with a stable and parallel regulatory pattern of HF-HRV from baseline to postneedle. The second group (7.9%) had parallel regulatory trajectories but with notably lower (ie, less regulated) HF-HRV values, which indicates independent regulatory responses (ie, a lack of attunement among dyad members). The third group (11.1%) showed diverging regulatory trajectories: Caregivers showed a stable regulatory trajectory, but toddlers demonstrated a steep decrease followed by an increase in HF-HRV values that surpassed their baseline levels by the third minute postneedle. Post hoc analyses with the HF-HRV groupings explored heart rate patterns and potential predictors.

Conclusions

These findings elucidate potential adaptive and maladaptive co-regulatory parasympathetic patterns in an acute pain context.

Parent-child dyads with greater parenting stress exhibit less synchrony in posterior areas and more synchrony in frontal areas of the prefrontal cortex during shared play

Parent-child dyads who are mutually attuned to each other during social interactions display interpersonal synchrony that can be observed behaviorally and through the temporal coordination of brain signals called interbrain synchrony. Parenting stress undermines the quality of parent-child interactions. However, no study has examined synchrony in relation to parenting stress during everyday shared play. The present fNIRS study examined the association between parenting stress and interbrain synchrony in the prefrontal cortex (PFC) of 31 mother-child and 29 father-child dyads while they engaged in shared play for 10 min. Shared play was micro-analytically coded into joint and non-joint segments. Interbrain synchrony was computed using cross-correlations over 15-, 20-, 25-, 30- and 35-s fixed-length windows. Findings showed that stressed dyads exhibited less synchrony in the posterior right cluster of the PFC during joint segments of play, and, contrary to expectations, stressed dyads also showed greater synchrony in the frontal left cluster. These findings suggest that dyads with more parenting stress experienced less similarities in brain areas involved in emotional processing and regulation, whilst simultaneously requiring greater neural entrainment in brain areas that support task management and social-behavioral organization in order to sustain prolonged periods of joint interactions.

Definitions, theories, and measurement of stress in children

PROBLEM

Stress in children remains a complex concept to examine due to the inherent subjectivity and lack of specific manifestations, as well as the multiple ways stress can be defined and measured in children. Because stress is multifactorial,is experienced daily by children, and undergirds adolescent health and early mental illness, it is crucial to have a clear understanding of stress and the effects of stress in children from infancy through age twelve years.

ELIGIBILITY CRITERIA

To be included in this review, literature must pertain to and highlight theories, definitions/classifications, and measurements of stress in children from infancy to 12 years of age.

SAMPLE

The most pertinent articles identified through database searches (PubMed, Scopus, PsycINFO, CINAHL, Google Scholar), gray literature sources (e.g., child health websites), and reference lists of identified articles were included in this narrative overview.

RESULTS

The results of this review are organized by themes and include: classifications and definitions of stress, stress-related theories, and tools to measure stress in children.

CONCLUSIONS

Research addressing stressors and stress in children is limited, and there is wide variation in how researchers define and classify stress in children. Existing measures of stress in children younger than 12 address physiological, psychological, and observational components, but may be inconsistent and threaten validity of otherwise well-designed and well-executed studies.

IMPLICATIONS

Improving the understanding and accurate measurement of stress in children enables researchers and clinicians to curtail undesirable health outcomes.

Caregiver and Young Child Biological Attunement In Distress Contexts: A Systematic Review and Narrative Synthesis

The objective of the current study was to systematically review the literature on caregiver-child biological attunement within distress contexts during the first three years of life. A total of 9932 unique abstracts were identified through Medline, Embase, PsycINFO, CINAHL, and Scopus databases. Thirty-six studies provided data from caregivers and their infants or toddlers within a distress paradigm, used biological indicators of distress, and assessed the relations between caregiver and child biological indicators. Findings were synthesized based on biological indicators, type of analysis, and measurement epochs pre- and post-distress. Most articles examined cortisol. Associations between caregiver and child cortisol indicators were moderate to large, though findings varied depending on the analysis used and measurement epochs examined. Many of the findings examining relations between mother and child cardiac, sAA, and EEG indicators were weak or inconsistent, likely due to the limitations of methodological approaches used to capture the complexity of the caregiver-child attunement process. Gaps in the literature and suggestions for future research are discussed.

Interpersonal Synchrony in the Context of Caregiver-Child Interactions: A Document Co-citation Analysis

Social interactions accompany individuals throughout their whole lives. When examining the underlying mechanisms of social processes, dynamics of synchrony, coordination or attunement emerge between individuals at multiple levels. To identify the impactful publications that studied such mechanisms and establishing the trends that dynamically originated the available literature, the current study adopted a scientometric approach. A sample of 543 documents dated from 1971 to 2021 was derived from Scopus. Subsequently, a document co-citation analysis was conducted on 29,183 cited references to examine the patterns of co-citation among the documents. The resulting network consisted of 1,759 documents connected to each other by 5,011 links. Within the network, five major clusters were identified. The analysis of the content of the three major clusters-namely, "Behavioral synchrony," "Towards bio-behavioral synchrony," and "Neural attunement"-suggests an interest in studying attunement in social interactions at multiple levels of analysis, from behavioral to neural, by passing through the level of physiological coordination. Furthermore, although initial studies on synchrony focused mostly on parent-child interactions, new hyperscanning paradigms are allowing researchers to explore the role of biobehavioral synchrony in all social processes in a real-time and ecological fashion. Future potential pathways of research were also discussed.

Mothers' neural response to valenced infant interactions predicts postpartum depression and anxiety

It is currently unknown whether differences in neural responsiveness to infant cues observed in postpartum affective disturbance are specific to depression/anxiety or are better attributed to a common component of internalizing distress. It is also unknown whether differences in mothers’ brain response can be accounted for by effects of past episodes, or if current neural processing of her child may serve as a risk factor for development of future symptoms. Twenty-four mothers from a community-based sample participated in an fMRI session viewing their 3-month- old infant during tasks evoking positive or negative emotion. They were tracked across the ensuing 15 months to monitor changes in affective symptoms. Past and current episodes of depression and anxiety, as well as future symptoms, were used to predict differences in mothers’ hemodynamic response to their infant in positive compared to negative emotion contexts. Lower relative activation in largely overlapping brain regions involving frontal lobe structures to own infant positive vs. negative emotion was associated with concurrent (3-month) depression diagnosis and prospective (3–18 month) depression and anxiety symptoms. There was little evidence for impacts of past psychopathology (more limited effect of past anxiety and nonsignificant effect of past depression). Results suggest biased maternal processing of infant emotions during postpartum depression and anxiety is largely accounted for by a shared source of variance (internalizing distress). Furthermore, differential maternal responsiveness to her infant’s emotional cues is specifically associated with the perpetuation of postpartum symptoms, as opposed to more general phenotypic or scarring effects of past psychopathology.

Maternal experiences of childhood maltreatment moderate patterns of mother-infant cortisol regulation under stress

The relation between maternal and infant cortisol responses has been a subject of intense research over the past decade. Relatedly, it has been hypothesized that maternal history of childhood maltreatment (MCM) impacts stress regulation across generations. The current study employed four statistical approaches to determine how MCM influences the cortisol responses of 150 mothers and their 4-month-old infants during the Still-Face Paradigm. Results indicated that MCM moderated cortisol patterns in several ways. First, lower MCM mothers and infants had strong positive associations between cortisol levels measured at the same time point, whereas higher MCM mothers and infants did not show an association. Second, infants of higher MCM mothers had cortisol levels that were moderately high and remained elevated over the procedure, whereas infants of lower MCM mothers had decreasing cortisol levels over time. Third, higher MCM mothers and infants showed increasingly divergent cortisol levels over time, compared to lower MCM dyads. Finally, patterns of cross-lagged influence of infant cortisol on subsequent maternal cortisol were moderated by MCM, such that lower MCM mothers were influenced by their infants' cortisol levels at earlier time points than higher MCM mothers. These findings highlight MCM as one contributor to processes of stress regulation in the mother-infant dyad.

In infancy, it's the extremes of arousal that are 'sticky': Naturalistic data challenge purely homeostatic approaches to studying self-regulation

Most theoretical models of arousal/regulatory function emphasise the maintenance of homeostasis; consistent with this, most previous research into arousal has concentrated on examining individuals' recovery following the administration of experimentally administered stressors. Here, we take a different approach: we recorded day-long spontaneous fluctuations in autonomic arousal (indexed via electrocardiogram, heart rate variability and actigraphy) in a cohort of 82 typically developing 12-month-old infants while they were at home and awake. Based on the aforementioned models, we hypothesised that extreme high or low arousal states might be more short-lived than intermediate arousal states. Our results suggested that, contrary to this, both low- and high-arousal states were more persistent than intermediate arousal states. The same pattern was present when the data were viewed over multiple epoch sizes from 1 s to 5 min; over 10-15-minute time-scales, high-arousal states were more persistent than low- and intermediate states. One possible explanation for these findings is that extreme arousal states have intrinsically greater hysteresis; another is that, through 'metastatic' processes, small initial increases and decreases in arousal can become progressively amplified over time. Rather than exclusively using experimental paradigms to study recovery, we argue that future research should also use naturalistic data to study the mechanisms through which states can be maintained or amplified over time.

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.

Evidence for discrete profiles of children's physiological activity across three neurobiological system and their transitions over time

The conceptualization of stress-responsive physiological systems as operating in an integrated manner is evident in several theoretical models of cross-system functioning. However, limited empirical research has modeled the complexity of multisystem activity. Moreover few studies have explored developmentally regulated changes in multisystem activity during early childhood when plasticity is particularly pronounced. The current study used latent profile analysis (LPA) to evaluate multisystem activity during fall and spring of children's transition to kindergarten in three biological systems: the parasympathetic nervous system (PNS), sympathetic nervous system (SNS), and hypothalamic pituitary adrenal (HPA) axis. Latent transition analysis (LTA) was then used to examine the stability of profile classification across time. Across both timepoints, three distinct profiles of multisystem activity emerged. One profile was characterized by heightened HPA axis activity (HPA Axis Responders), a second profile was characterized by moderate, typically adaptive patterns across the PNS, SNS, and HPA axis (Active Copers/Mobilizers), and a third profile was characterized by heightened baseline activity, particularly in the PNS and SNS (Anticipatory Arousal/ANS Responders). LTA of fall-to-spring profile classifications indicated higher probabilities that children remained in the same profile over time compared to probabilities of profile changes, suggesting stability in certain patterns of cross-system responsivity. Patterns of profile stability and change were associated with socioemotional outcomes at the end of the school year. Findings highlight the utility of LPA and LTA to detect meaningful patterns of complex multisystem physiological activity across three systems and their associations with early adjustment during an important developmental transition.

Intimate partner violence indirectly dysregulates child diurnal adrenocortical functioning through positive parenting

Data were drawn from an ongoing study of preschoolers (N = 221). Mothers self-reported experiences of intimate partner violence (IPV) and parenting practices, and collected three saliva samples (waking, midday, and bedtime) on themselves and their child on 2 consecutive days. Saliva samples were later assayed for cortisol. Bootstrapped mediation analyses revealed IPV to indirectly impact child diurnal cortisol through positive parenting. Specifically, greater exposure to IPV was associated with reduced positive parenting and subsequently heightened child waking cortisol levels. IPV did not indirectly impact child diurnal cortisol via autonomy supporting parenting or maternal diurnal cortisol. These findings suggest a possible pathway by which mother's experience of IPV indirectly influences child physiological regulation via maternal positive parenting.

Intimate partner violence indirectly dysregulates child diurnal adrenocortical functioning through positive parenting

Data were drawn from an ongoing study of preschoolers (N = 221). Mothers self-reported experiences of intimate partner violence (IPV) and parenting practices, and collected three saliva samples (waking, midday, and bedtime) on themselves and their child on two consecutive days. Saliva samples were later assayed for cortisol. Bootstrapped mediation analyses revealed IPV to indirectly impact child diurnal cortisol through positive parenting. Specifically, greater exposure to IPV was associated with reduced positive parenting and subsequently heightened child waking cortisol levels. IPV did not indirectly impact child diurnal cortisol via autonomy supporting parenting or maternal diurnal cortisol. These findings suggest a possible pathway by which mother's experience of IPV indirectly influences child physiological regulation via maternal positive parenting.

Child depressive symptoms: Associations with salivary cortisol and alpha amylase in two distinct challenges

Child depression has been inconsistency linked to cortisol and salivary alpha-amylase (sAA) reactivity. This study assessed three factors that contribute to inconsistencies: 1) the differential effectiveness of laboratory challenges to elicit cortisol and sAA; 2) the impact of cortisol-sAA coordination; and 3) variation in parent versus child ratings of depression. A community sample of 52 children participated in the Trier Social Stress Test-Child Version (TSST-C) and a competition challenge. Saliva was collected and assayed for cortisol and sAA. Analyses were conducted using multilevel modeling. Child-reported depressive symptoms were associated with a declining cortisol trajectory in the TSST-C. Mother-reported depressive symptoms were associated with higher baseline sAA in the TSST-C and the competition challenge. Further, child-reported depressive symptoms were associated with cortisol-sAA coordination in the competition challenge. Findings underscore the nature of the challenge and the behavioral informant as impacting associations between child depressive symptoms and cortisol and sAA secretion.

Child Maltreatment and Mother-Child Transmission of Stress Physiology

In the current study, we examined the attunement and transmission of mother-child diurnal cortisol among maltreating (N = 165) and nonmaltreating (N = 83) mothers and their preschool-aged children. Over half of the families had a substantiated child maltreatment case with the mother as the perpetrator. Mothers collected three saliva samples (waking, midday, and bedtime) on themselves and their child on two consecutive days, which were later assayed for cortisol. This design allows for the examination of concurrent attunement, as well as cross-lagged transmission, across the day. Results from actor-partner interdependence models revealed significant differences in mother-child cortisol attunement and transmission between the maltreating and nonmaltreating groups. Specifically, only maltreating mothers transmitted cortisol to their children and were attuned at first waking; only nonmaltreating dyads were attuned at midday. Implications of these results for sociocultural models of stress physiology and for our understanding of how child maltreatment affects diurnal cortisol regulation are discussed.

The cross-sectional and prospective associations between sleep characteristics and adiposity in toddlers: Results from the GET UP! Study

BACKGROUND

The associations between sleep characteristics and adiposity in children under three years are not fully understood yet.

OBJECTIVE

The objective of the study is to examine the cross-sectional and prospective associations between sleep characteristics and adiposity in toddlers over a 12-month period.

METHODS

Participants were 202 toddlers from the GET-UP!

STUDY

Sleep duration, sleep timing, and sleep variability were assessed using 24-hour accelerometry for seven consecutive days. Height and weight were measured, and BMI z scores were calculated. Linear mixed models were performed to examine the cross-sectional and prospective associations between sleep characteristics and adiposity, with adjustments for clustering effects and demographic factors.

RESULTS

Total sleep duration was negatively associated with higher adiposity cross-sectionally (B = -0.12; 95% CI: -0.23, -0.01; .033) but not prospectively (B = 0.01; 95% CI: -0.13, 0.10; .843). Nap duration was prospectively associated with higher levels of adiposity (B = 0.41; 95% CI: 0.14, 0.68; .003). Sleep variability and sleep timing were not associated with concurrent or subsequent adiposity.

CONCLUSION

Although sleep duration is an important factor associated with obesity in toddlerhood, the potential effects of different types of sleep duration may vary. While longer total sleep duration may protect children from increasing adiposity, longer nap duration seems to be risk factor. As evidence in this age group is scarce, more research is needed to confirm this finding.

Adrenocortical and autonomic attunement between romantic partners in emerging adulthood

Parent-child physiological attunement, particularly during stressful situations, appears adaptive as shared stress reactivity may promote dyadic engagement. Romantic partners eventually replace parents as the primary support figure, yet it remains unclear whether romantic partners buffer physiological stress or display physiological attunement as most studies on adults examine attunement during conflict paradigms. The present study examined physiological attunement in 63 emerging adult romantic partner dyads (one partner was the active participant, the other the observer) during the Trier Social Stress Task (TSST). Heart rate (HR) and respiratory sinus arrhythmia (RSA) were continuously monitored across the visit. Repeated saliva samples were assayed for cortisol. Physiological attunement was operationalized as a correlation in biomarkers between the TSST participant and their partner; sex, social support, and physical proximity were examined as moderators. We then compared the biomarker profiles of partnered-TSST participants to individuals who participated in the TSST solo (n = 63) to determine if partner presence buffered stress biomarker reactivity during the TSST. RSA attunement between partners was found but was not further moderated by social support or sex. Adrenocortical attunement was moderated, such that lower social support and increased proximity resulted in higher attunement. HR attunement was higher when the participant was male and when partners were in close physical proximity. Compared to TSST solo, romantic partner presence increased participant cortisol levels and altered HR reactivity, suggesting that emerging adult romantic partners do not buffer physiological stress reactivity. Future research should examine whether physiological attunement and partner presence is protective in more established relationships.

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.

Mother–infant cortisol attunement: Associations with mother–infant attachment disorganization

This study explores the conceptualization of mother–infant cortisol attunement both theoretically and empirically, and its association with mother–infant attachment disorganization. In a community sample (N = 256), disorganization and cortisol were assessed during the Strange Situation Procedure (SSP) at infant age 17 months. Salivary cortisol was collected at baseline, and 20 and 40 min after the SSP. We utilized three statistical approaches: correlated growth modeling (probing a simultaneous conceptualization of attunement), cross-lagged modeling (probing a lagged, reciprocal conceptualization of attunement), and a multilevel model difference score analysis (to examine the pattern of discrepancies in mother–infant cortisol values). Correlated growth modeling revealed that disorganized, relative to organized, dyads had significant magnitude of change over time, such that, among disorganized dyads, as mothers had greater declines in cortisol, infants had greater increases. The difference score analysis revealed that disorganized, relative to organized, dyads had a greater divergence between maternal and infant cortisol values, such that maternal values were lower than infant values. Disorganized attachment status was not significantly associated with attunement when conceptualized as reciprocal and lagged in the cross-lagged model. Findings suggest that mother–infant dyads in disorganized attachment relationships, who are by definition behaviorally misattuned, are also misattuned in their adrenocortical responses.

The Power of Play: A Pediatric Role in Enhancing Development in Young Children

Children need to develop a variety of skill sets to optimize their development and manage toxic stress. Research demonstrates that developmentally appropriate play with parents and peers is a singular opportunity to promote the social-emotional, cognitive, language, and self-regulation skills that build executive function and a prosocial brain. Furthermore, play supports the formation of the safe, stable, and nurturing relationships with all caregivers that children need to thrive.Play is not frivolous: it enhances brain structure and function and promotes executive function (ie, the process of learning, rather than the content), which allow us to pursue goals and ignore distractions.When play and safe, stable, nurturing relationships are missing in a child's life, toxic stress can disrupt the development of executive function and the learning of prosocial behavior; in the presence of childhood adversity, play becomes even more important. The mutual joy and shared communication and attunement (harmonious serve and return interactions) that parents and children can experience during play regulate the body's stress response. This clinical report provides pediatric providers with the information they need to promote the benefits of play and and to write a prescription for play at well visits to complement reach out and read. At a time when early childhood programs are pressured to add more didactic components and less playful learning, pediatricians can play an important role in emphasizing the role of a balanced curriculum that includes the importance of playful learning for the promotion of healthy child development.

The Energy Costs of Prematurity and the Neonatal Intensive Care Unit (NICU) Experience

Premature neonates are in an energy deficient state due to (1) oxygen desaturation and hypoxia events, (2) painful and stressful stimuli, (3) illness, and (4) neurodevelopmental energy requirements. Failure to correct energy deficiency in premature infants may lead to adverse effects such as neurodevelopmental delay and negative long-term metabolic and cardiovascular outcomes. The effects of energy dysregulation and the challenges that clinicians in the Neonatal Intensive Care Unit (NICU) face in meeting the premature infant's metabolic demands are discussed. Specifically, the focus is on the effects of pain and stress on energy homeostasis. Energy deficiency is a complex problem and requires a multi-faceted solution to promote optimum development of premature infants.

Physiological attunement in mother–infant dyads at clinical high risk: The influence of maternal depression and positive parenting

A growing number of research studies have examined the intradyadic coregulation (or attunement) of hypothalamus–pituitary–adrenal axis functioning in mothers and their children. However, it is unclear how early this coregulation may be present in dyads at clinical high risk and whether certain factors, such as maternal depression or positive parenting, are associated with the strength of this coregulation. The present study examined cortisol attunement within mother–infant dyads in a high-risk sample of 233 mothers who received treatment for psychiatric illness during pregnancy and whose infants were 6 months old at the study visit. Results showed that maternal and infant cortisol covaried across four time points that included a stressor paradigm and a mother–infant interaction task. Greater maternal positive affect, but not depression, predicted stronger cortisol attunement. In addition, infants’ cortisol level following separation from the mother predicted mothers’ cortisol level at the next time point. Mothers’ cortisol level following the separation and the laboratory stress paradigm predicted infants’ cortisol levels at each successive time point, over and above infants’ own cortisol at the previous time point. These findings suggest that maternal and infant cortisol levels influence one another in a bidirectional fashion that may be temporally and context dependent.

An assessment of hair cortisol among postpartum Brazilian mothers and infants from a high-risk community in São Paulo: Intra-individual stability and association in mother-infant dyads

This study examined maternal-infant synchrony of hair cortisol at 12 months after birth and the intra-individual stability of maternal hair cortisol in the postpartum period. Participants were selected from an ongoing São Paulo birth cohort project, where families are considered to be "high-risk" due to their chronic stress experiences, with the majority living in slums (favelas). Cortisol was collected through 3-cm segments of hair samples, with values representing approximate levels of cortisol from 9 to 12 months for mothers and children and 6 to 12 months for mothers. Maternal and infant cortisol values reflecting chronic stress 9-12 months after birth were highly correlated (r = .61, p < .001); earlier maternal cortisol levels (6-9 months) and child cortisol levels at 9-12 months (r = .51, p < .001) were also correlated. Maternal cortisol values showed stability over time (r = .79, p < .001). These maternal-infant correlations are high compared to the existing literature on hair cortisol in other mother-child dyads, suggesting stronger synchrony under high-risk contexts where families are faced with challenging circumstances.

Dopamine receptor D2 (DRD2), dopamine transporter solute carrier family C6, member 4 (SLC6A3), and catechol-O-methyltransferase (COMT) genes as moderators of the relation between maternal history of maltreatment and infant emotion regulation

Although infants less than 18 months old are capable of engaging in self-regulatory behavior (e.g., avoidance, withdrawal, and orienting to other aspects of their environment), the use of self-regulatory strategies at this age (as opposed to relying on caregivers) is associated with elevated behavioral and physiological distress. This study investigated infant dopamine-related genotypes (dopamine receptor D2 [DRD2], dopamine transporter solute carrier family C6, member 4 [SLC6A3], and catechol-O-methyltransferase [COMT]) as they interact with maternal self-reported history of maltreatment to predict observed infant independent emotion regulation behavior. A community sample (N = 193) of mother–infant dyads participated in a toy frustration challenge at infant age 15 months, and infant emotion regulation behavior was coded. Buccal cells were collected for genotyping. Maternal maltreatment history significantly interacted with infant SLC6A3 and COMT genotypes, such that infants with more 10-repeat and valine alleles of SLC6A3 and COMT, respectively, relative to infants with fewer or no 10-repeat and valine alleles, utilized more independent (i.e., maladaptive) regulatory behavior if mother reported a more extensive maltreatment history, as opposed to less. The findings indicate that child genetic factors moderate the intergenerational impact of maternal maltreatment history. The results are discussed in terms of potential mechanism of Gene × Environment interaction.