Development of cardiac autonomic balance in infancy and early childhood: A possible pathway to mental and physical health outcomes

Assessing Children's Autonomic Nervous System Activity During Structured Tasks: A Feasibility and Reliability Study in Ghana

The significance of physiological regulation in relation to behavioral and emotional regulation is well documented, but primarily in economically advantaged contexts. Few studies have been conducted in low- and middle-income countries. We investigated the feasibility and reliability of measuring autonomic nervous system (ANS) activity and behavior during challenge tasks in 30 children aged 8-10 years in Ghana during two visits, 1 week apart. Completeness of ANS data ranged from 80% to 100% across all tasks. There was low-to-moderate test-retest reliability of video mood induction (VMI) emotion ratings and balloon analog risk task (BART) pumps (r = 0.34-0.52). VMI elicited higher targeted emotion ratings in Visit 2 than Visit 1. Respiratory sinus arrhythmia (RSA) was higher, and pre-ejection period (PEP) was longer at Visit 2 than Visit 1 for baseline and both tasks. RSA was higher at baseline than during the VMI anger scene at Visit 1, whereas PEP was shorter at baseline than during all VMI emotion scenes at Visit 2. RSA was higher at baseline than during BART at both visits. In conclusion, ANS data collection within evocative and arousing challenge tasks was feasible in Ghana, and the tasks were generally reliable and effective in eliciting target emotions and risk-taking behavior in this sample.

The Predictive Potential of Heart Rate Variability for Depression

Heart rate variability (HRV),a measure of the fluctuations in the intervals between consecutive heartbeats, is an indicator of changes in the autonomic nervous system. A chronic reduction in HRV has been repeatedly linked to clinical depression. However, the chronological and mechanistic aspects of this relationship, between the neural, physiological, and psychopathological levels, remain unclear. In this review we present evidence by which changes in HRV might precede the onset of depression. We describe several pathways that can facilitate this relationship. First, we examine a theoretical model of the impact of autonomic imbalance on HRV and its role in contributing to mood dysregulation and depression. We then highlight brain regions that are regulating both HRV and emotion, suggesting these neural regions, and the Insula in particular, as potential mediators of this relationship. We also present additional possible mediating mechanisms involving the immune system and inflammation processes. Lastly, we support this model by showing evidence that modification of HRV with biofeedback leads to an improvement in some symptoms of depression. The possibility that changes in HRV precede the onset of depression is critical to put to the test, not only because it could provide insights into the mechanisms of the illness but also because it may offer a predictive anddiagnosticphysiological marker for depression. Importantly, it could also help to develop new effective clinical interventions for treating depression.

Effects of prenatal opioid exposure on infant sympathetic and parasympathetic nervous system activity

Prenatal opioid exposure has been associated with developmental problems, including autonomic nervous system dysregulation. However, little is known about the effects of prenatal opioid exposure on the autonomic nervous system beyond the first days of life, particularly across both the parasympathetic and sympathetic branches, and when accounting for exposure to other substances. The present study examined the effects of prenatal exposure to opioid agonist therapy (OAT, e.g., methadone) and other opioids on infant autonomic nervous system activity at rest and in response to a social stressor (the Still-Face Paradigm) at six months among 86 infants varying in prenatal opioid and other substance exposure. Results indicated that OAT and other opioids have unique effects on the developing autonomic nervous system that may further depend on subtype (i.e., methadone versus buprenorphine) and timing in gestation. Results are discussed in the context of theoretical models of the developing stress response system.

Public health nurse-delivered cognitive behavioral therapy for postpartum depression: Assessing the effects of maternal treatment on infant emotion regulation

The effects of maternal postpartum depression (PPD) on offspring emotion regulation (ER) are particularly deleterious as difficulties with ER predict an increased risk of psychopathology. This study examined the impact of maternal participation in a public health nurse (PHN)-delivered group cognitive behavioral therapy (CBT) intervention on infant ER. Mothers/birthing parents were ≥ 18 years old with an Edinburgh Postnatal Depression Scale (EPDS) score ≥ 10, and infants were < 12 months. Between 2017 and 2020, 141 mother-infant dyads were randomized to experimental or control groups. Infant ER was measured at baseline (T1) and nine weeks later (T2) using two neurophysiological measures (frontal alpha asymmetry (FAA) and high-frequency heart rate variability (HF-HRV)), and informant-report of infant temperament. Mothers were a mean of 30.8 years old (SD = 4.7), 92.3% were married/ common-law, and infants were a mean of 5.4 months old (SD = 2.9) and 52.1% were male. A statistically significant group-by-time interaction was found to predict change in HF-HRV between T1 and T2 (F(1,68.3) = 4.04, p = .04), but no significant interaction predicted change in FAA or temperament. Results suggest that PHN-delivered group CBT for PPD may lead to adaptive changes in a neurophysiological marker of infant ER, highlighting the importance of early maternal intervention.

Prenatal fluoride exposure, offspring visual acuity and autonomic nervous system function in 6-month-old infants

BACKGROUND

Prenatal fluoride exposure can have adverse effects on children's development; however, associations with visual and cardiac autonomic nervous system functioning are unknown. We examined associations between prenatal fluoride exposure and visual acuity and heart rate variability (HRV) in 6-month-old infants.

METHODS

We used data from Canadian mother-infant pairs participating in the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort. We estimated prenatal fluoride exposure using: i) fluoride concentration in drinking water (mg/L), ii) maternal urinary fluoride adjusted for specific gravity (MUFSG; mg/L) and averaged across pregnancy, and iii) maternal fluoride intake (µg/kg/day) from consumption of water, tea, and coffee, adjusted for maternal body weight (kg). We used multivariable linear regression to examine associations between each measure of fluoride exposure and Teller Acuity Card visual acuity scores (n = 435) and assessed HRV (n = 400) using two measures: root mean square of successive differences (RMSSD) and the standard deviation of N-N intervals (SDNN) measured at 6-months of age.

RESULTS

Median (IQR) values for water fluoride, MUFSG, and daily fluoride intake were 0.20 (IQR: 0.13-0.56) mg/L; 0.44 (0.28-0.70) mg/L and 4.82 (2.58-10.83) µg/kg/day, respectively. After adjustment for confounding variables, water fluoride concentration was associated with poorer infant visual acuity (B = -1.51; 95 % CI: -2.14,-0.88) and HRV as indicated by lower RMSSD (B = -1.60; 95 % CI: -2.74,-0.46) but not SDNN. Maternal fluoride intake was also associated with poorer visual acuity (B = -0.82; 95 % CI: -1.35,-0.29) and lower RMSSD (B = -1.22; 95 % CI: -2.15,-0.30). No significant associations were observed between MUFSG and visual acuity or HRV.

CONCLUSION

Fluoride in drinking water was associated with reduced visual acuity and alterations in cardiac autonomic function in infancy, adding to the growing body of evidence suggesting fluoride's developmental neurotoxicity.

Cardiac Autonomic Balance Is Altered during the Acute Stress Response in Adolescent Major Depression-Effect of Sex

Autonomic nervous system (ANS) abnormalities are associated with major depressive disorder (MDD) already at adolescent age. The majority of studies so far evaluated parasympathetic and sympathetic branches of ANS individually, although composite indices including cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR) seem to measure ANS functioning more comprehensively and thus could provide better psychopathologies' predictors. We aimed to study CAB and CAR derived from high-frequency bands of heart rate variability and left ventricular ejection time during complex stress response (rest-Go/NoGo task-recovery) in MDD adolescents with respect to sex. We examined 85 MDD adolescents (52 girls, age: 15.7 ± 0.14 yrs.) and 80 age- and sex-matched controls. The MDD group showed significantly reduced CAB compared to controls at rest, in response to the Go/NoGo task, and in the recovery phase. Moreover, while depressed boys showed significantly lower CAB at rest and in response to the Go/NoGo task compared to control boys, depressed girls showed no significant differences in evaluated parameters compared to control girls. This study for the first time evaluated CAB and CAR indices in drug-naïve first-episode diagnosed MDD adolescents during complex stress responses, indicating an altered cardiac autonomic pattern (i.e., reciprocal sympathetic dominance associated with parasympathetic underactivity), which was predominant for depressed boys.

Risk for internalizing symptom development in young children: Roles of child parasympathetic reactivity and maternal depression and anxiety exposure in early life

Intergenerational transmission of internalizing disorders (anxiety and depression) is well documented, but the responsible pathways are underspecified. One possible mechanism is via programming of the child's parasympathetic nervous system (PNS). For example, maternal depression and anxiety, via multiple pathways, may heighten child PNS reactivity, which has been linked to increased risk for internalizing disorders. Heightened PNS reactivity also may sensitize a child to their environment, increasing the vulnerability to developing psychopathology when exposed to stressors, such as maternal psychopathology. In a prospective longitudinal study of mother-child dyads (N = 446), we examined relations among maternal depression and anxiety symptoms when children were infants and aged 3 and 5 years, child respiratory sinus arrythmia (RSA) reactivity (measure of PNS reactivity) at 3 years, and child internalizing symptoms at age 5 years. Consistent with an adaptive calibration perspective, analyses tested the roles of child RSA reactivity as both a mediator and a moderator of associations between maternal and child symptoms. Greater child RSA reactivity in response to a fearful video predicted higher internalizing symptoms among children exposed to higher levels of maternal depression or anxiety symptoms at age 5 years (moderation effects). Child RSA reactivity did not mediate relations between maternal depression or anxiety symptoms in infancy and child internalizing symptoms at age 5 years. The results suggest that heightened PNS reactivity may represent a biological vulnerability to stressful environments early in life: When coupled with maternal depression or anxiety exposure, child PNS reactivity may promote the development of internalizing psychopathology in early childhood.

The role of social adversity on emotional dysregulation during infancy and early childhood

PURPOSE

The purpose of this study was to investigate if social adversity is associated with mother reported emotional dysregulation behaviors and trajectories during infancy and early childhood.

DESIGN & METHODS

A secondary data analysis from the Durham Child Health and Development study study included 206 child-mother dyads. Three models were used to explore the relationship between social adversity and mother reported emotional dysregulation during infancy (Infant Behavior Questionnaire-Revised) and early childhood (Child Behavior Checklist - Dysregulation Profile). Linear mixed effects models were adopted to investigate if social adversity was associated with mother reported emotional dysregulation longitudinally. Regression analysis was conducted to explore if social adversity was associated with maternal reported emotional dysregulation trajectory slope scores and maternal reported emotional dysregulation trajectory class. Maternal psychological distress and the child's sex assigned at birth were included as covariates in each analysis.

RESULTS

Infants with greater social adversity scores had significantly higher maternal reported fear responses across the first year of life. Social adversity was associated with maternal reported distress to limitations trajectory, dysregulated recovery class, and dysregulated distress to limitations class. During early childhood social adversity was significantly associated with maternal reported emotional dysregulation but not trajectories which showed little variability.

CONCLUSION & PRACTICAL IMPLICATIONS

Our results indicate that social adversity is associated with maternal reported emotional dysregulation during infancy and early childhood. Nursing and other professionals can participate in early screening to determine risk and provide intervention.

Dampened autonomic nervous system responses to stress and substance use in adolescence

We investigated whether parasympathetic and sympathetic nervous system (SNS) responses to social-evaluative threat at age 14 were related to the number of substances used between ages 14 and 16 among Mexican-origin adolescents (N = 243; 70.4% had never used substances by 14). Participants completed the Trier Social Stress Test, while cardiac measures of parasympathetic and SNS activity were measured continuously using respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), respectively. Participants reported whether they had ever used alcohol, marijuana, and cigarettes, and had ever vaped nicotine in their lifetime at ages 14 and 16. Multilevel models were used to test associations between RSA and PEP responses at age 14 and substance use at 16. Among youth who had not used substances by 14, dampened RSA and PEP responses, and profiles of greater coinhibition and lower reciprocal SNS activation between RSA and PEP, at age 14 were associated with using substances by 16. Among youth who used by 14, exaggerated PEP responses were associated with using more substances by age 16. Taken together, dampened autonomic responses to social-evaluative threat predicted initiation of substance use over two years, and difficulties with coordination of physiological responses may confer risk for substance use in adolescence.

Dynamics of mother-infant parasympathetic regulation during face-to-face interaction: The role of maternal emotion dysregulation

The dynamics of parent-infant physiology are essential for understanding how biological substrates of emotion regulation are organized during infancy. Although parent-infant physiological processes are dyadic in nature, research is limited in understanding how one person's physiological responses predict one's own and as well as the other person's responses in the subsequent moment. In this study, we examined mother-infant respiratory sinus arrhythmia (RSA) dynamics during the Still-Face Paradigm (SFP) among 106 mothers (M_age  = 29.54) and their 7-month-old infants (55 males). Given mothers' role in shaping dyadic interactions with their infant, we also tested how mothers' self-reported emotion dysregulation (measured via the Difficulties in Emotion Regulation Scale) associated with these dynamics. Results showed that both mothers' and infants' RSA tended to return to their respective homeostatic points (i.e., exhibited return strength) during each SFP episode, indicating stability in RSA for mother-infant dyads. Significant shifts in mother and infant RSA return strength were observed across SFP episodes, highlighting the role of contextual demands on each individual's physiological dynamics. Mother-infant RSA dynamics varied as a function of maternal self-reported emotion dysregulation. Specifically, RSA levels of infants with more dysregulated mothers had a weaker tendency to return to homeostasis during the Reunion episode and were less affected by their mothers' RSA during the Still-Face and Reunion episodes of the SFP, suggesting a less effective coregulatory influence. Our findings have implications for the intergenerational transmission of emotion dysregulation via mother-infant physiological dynamics.

Effects of an attachment-based intervention on autonomic regulation among opioid-exposed infants

Little is known about whether postnatal intervention enhances autonomic regulation among infants at risk for dysregulation due to prenatal opioid exposure. The present study evaluated the effects of modified Attachment Behavioral Catch-up (mABC) on autonomic regulation for opioid-exposed infants in a pilot randomized clinical trial. We hypothesized that, compared to a control intervention (modified Developmental Education for Families [mDEF]), mABC would be associated with higher resting respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP) as well as greater reactivity to and recovery from a social stressor (Still-Face Paradigm). Pregnant or peripartum women receiving opioid agonist therapy (61 mothers of 64 infants; final N = 36 infants) were randomly assigned to mABC or mDEF, 12-session home visiting programs beginning in the third trimester; mABC targets sensitive parenting, and mDEF targets cognitive and motor development. mABC was associated with significantly greater RSA reactivity and marginally greater PEP reactivity. In models accommodating missing data, mABC was additionally associated with significantly greater RSA recovery. In sensitivity analyses removing siblings, mABC predicted significantly enhanced PEP reactivity. Overall, in these preliminary analyses, mABC was associated with healthier autonomic regulation during a social stressor than mDEF. Thus, mABC may be a promising strategy to promote autonomic regulation among opioid-exposed infants through parenting intervention.

A systematic review and meta-analysis of the association between parenting and child autonomic nervous system activity

Parental socialization may influence the development of children's autonomic nervous system (ANS), a key stress-response system. However, to date no quantitative synthesis of the literature linking parenting and child ANS physiology has been conducted. To address this gap, we conducted a pre-registered meta-analysis. A systematic review of the literature identified 103 studies (n = 13,044 participants) with available effect sizes describing the association between parenting and either parasympathetic nervous system (PNS) or sympathetic nervous system (SNS) activity in children. The overall analysis revealed non-significant associations between parenting and child ANS physiology on average. However, moderation analyses revealed a positive association between more positive parenting and higher resting PNS activity that was stronger when a study was experimental rather than correlational, and when the sample included children with a clinical condition. In conclusion, well-controlled experimental studies show that positive parenting is associated with the development of higher resting PNS activity, an effect that may be stronger among children who are at elevated developmental risk.

Heart rate variability in 2014 predicted delayed onset of internalizing problems in 2015 among children affected by the 2011 Great East Japan Earthquake

Experience of natural disaster was related to an increased risk of long-term child internalizing problems. Initial traumatic experiences are hypothesized to work as disaster-related stresses and sensitize neural circuitry, leading to heightened reactivity to subsequent stressful experiences, which in turn results in delayed onset of internalizing problems. However, empirical evidence is lacking. Thus, we aimed to examine the association between heart rate variability (HRV) and internalizing problems among children exposed to the disaster. The Great East Japan Earthquake Follow-up for Children (GEJE-FC) study followed children aged 4-6 years old and their siblings and parents from three affected prefectures (Miyagi, Fukushima, and Iwate) and one unaffected prefecture (Mie) in Japan over four periods: from August 2012 to June 2013 (= T1), August 2013 to April 2014 (= T2), July 2014 to December 2014 (= T3), and August 2015 to December 2015 (= T4) (n = 155). HRV was assessed at T2 and T3 as a biomarker of autonomic nervous system activity. Child internalizing problems were assessed by caregivers at T3 and T4, using the Child Behavior Checklist. HRV measurements at T2 were not associated with child internalizing problems at T3. However, HRV in low frequency domains at T3 showed an inverse association with child internalizing problems at T4 (B = -1.72, 95% CI = -3.12 to -0.31). The findings indicated that later exacerbation of internalizing problems could be predicted by dysfunction of autonomic nervous system measured by HRV.

The cholinergic anti-inflammatory pathway in humans: State-of-the-art review and future directions

The parasympathetic nervous system modulates inflammation through efferent vagus nerve signaling. Tracey (2002) termed this process as the cholinergic anti-inflammatory pathway (CAP). Interest in the potential practical use of this immune-modulatory process is increasing alongside increasing appreciation for the role of systemic inflammation in the etiology of somatic and psychological disease. A diverse literature exists providing expansive correlational evidence and some preliminary experimental evidence of the CAP in humans. However, so far this literature has not been well integrated and critically evaluated. This review describes the current state-of-the-art of research into vagus nerve driven parasympathetic control of inflammation in humans. Substantial limitations and gaps in the literature are identified, and promising directions for future research are highlighted.

The impact of social disadvantage on autonomic physiology of latinx adolescents: The role of environmental risks

The experience of poverty embodies complex, multidimensional stressors that may adversely affect physiological and psychological domains of functioning. Compounded by racial/ethnic discrimination, the financial aspect of family poverty typically coincides with additional social and physical environmental risks such as pollution exposure, housing burden, elevated neighborhood unemployment, and lower neighborhood education levels. In this study, we investigated the associations of multidimensional social disadvantage throughout adolescence with autonomic nervous system (ANS) functioning at 17 years. Two hundred and twenty nine low-income Mexican-American adolescents (48.6% female) and their parents were assessed annually between the ages of 10 and 16. Participants' census tracts were matched with corresponding annual administrative data of neighborhood housing burden, education, unemployment, drinking water quality, and fine particulate matter. We combined measures of adolescents' electrodermal response and respiratory sinuses arrhythmia at rest and during a social exclusion challenge (Cyberball) to use as ANS indices of sympathetic and parasympathetic activity, respectively. Controlling for family income-to-needs, youth exposed to greater cumulative water and air pollution from ages 10-16 displayed altered patterns of autonomic functioning at rest and during the social challenge. Conversely, youth living in areas with higher housing burden displayed healthy patterns of autonomic functioning. Altogether, results suggest that toxin exposure in youths' physical environments disrupts the ANS, representing a plausible mechanism by which pollutants and social disadvantage influence later physical and mental health.

Quantifying the dynamic nature of vagal responsivity in infancy: Methodological innovations and theoretical implications

According to polyvagal theory, rapid modulation of the vagal brake develops early in infancy and supports social interactions. Despite being viewed as a dynamic system, researchers typically assess vagal regulation using global measures of respiratory sinus arrhythmia (RSA; an index of vagal tone). This study sought to capture the dynamic property of RSA and evaluate individual differences in within-infant RSA responsivity during mother-infant interaction. RSA was evaluated in a sample of 135 6-month-old Mexican-American infants during a 5-min free play task. Mothers reported on their children's behavioral problems and competence at 18 months using the Brief Infant-Toddler Social and Emotional Assessment. Time-varying estimates of infant RSA during the interaction were obtained using a multiple window technique and spectrogram analysis. Using structural equation modeling, we evaluated whether within-infant SD of RSA predicted infants' behavioral problems and competence at 18 months, after adjusting for infants' mean RSA and covariates. Greater within-infant SD of RSA predicted more behavior problems at 18 months. This study demonstrates that assessing intra-individual variability in RSA, or the extent to which infants fluctuate around their average level of RSA during a task, enhances our ability to test polyvagal theory's central tenet: vagal regulation supports well-regulated social interaction.

Children's altruism following acute stress: The role of autonomic nervous system activity and social support

Altruistic behavior after stress exposure may have important health and psychological benefits, in addition to broader societal consequences. However, so far experimental research on altruism following acute stress has been limited to adult populations. The current study utilized an experimental design to investigate how altruistic donation behavior among children may be influenced by (a) exposure to an acute social stressor, the Trier Social Stress Test modified for use with children (TSST-M), (b) individual differences in stress physiology, and (c) social support from a parent. The sample consisted of 180 children (54.9% male, 45.1% female; mean age = 9.92 years, SD = 0.56 years) randomly assigned to one of three conditions involving the TSST-M: (a) prepare for the TSST-M alone, (b) prepare for the TSST-M with a parent, and (c) no-stress control group. Results revealed that children made larger donations post-stressor if they were alone before the acute stressor, if they had moderate cardiac autonomic balance, reflecting both parasympathetic and sympathetic influence, and if they were older. Children who prepared for the TSST-M with social support from a parent made comparable donations as children in the no-stress control group, in accord with stress buffering models. Increased altruism following acute stress among children suggests that a comprehensive understanding of the human stress response needs to incorporate "tend-and-befriend" behavior-the tendency for humans to show increased altruistic behavior during times of distress.

Effects of maternal and paternal postnatal depressive symptoms on infants' parasympathetic regulation in low-income, Mexican American families

Mothers and fathers are at elevated risk for developing depression during the first postnatal year, especially among families from marginalized communities. Although a number of studies demonstrate that exposure to maternal depressive symptoms can undermine infants' regulatory development, less is known about the extent to which paternal depressive symptoms may also contribute. The current study investigated whether maternal and paternal depressive symptoms were uniquely associated with infants' physiological regulation, and whether associations varied depending on infant sex. Participants included 90 low-income Mexican American families. Fathers and mothers self-reported their depressive symptoms when infants were 15 weeks old, and infants' resting parasympathetic activity (i.e., respiratory sinus arrhythmia [RSA]) was assessed at 6 and 24 weeks. Results indicated that, after controlling for infant 6-week RSA and depressive symptoms in the other parent, paternal depressive symptoms were associated with lower 24-week RSA for both girls and boys, but maternal depressive symptoms were only associated with lower 24-week RSA for boys. Findings highlight a potential mechanism through which the consequences of parent depressive symptoms may reverberate across generations, and suggest that considerations of both infants' and parents' sex may lend insight into how best to intervene.

Socioemotional Mechanisms of Children's Differential Response to the Effects of Maternal Sensitivity on Child Adjustment

OBJECTIVE

Children differ in the extent to which they reap the benefits of maternal sensitive care or suffer the adverse consequences of insensitive care, and these differences can be accounted for by biological characteristics. However, how susceptible children adapt to maternal sensitivity in ways that either maximize positive development or lead to maladjustment has yet to be determined. Here, we propose a novel model of socioemotional mechanisms by which the joint influences of maternal sensitivity and child biological characteristics influence child adjustment.

DESIGN

We propose a theoretical model, in which children's vagal functioning and polymorphisms in serotonin transporter (5-HTTLPR) and dopamine receptor D4 (DRD4) genes confer susceptibility to the effects of maternal sensitivity on internalizing, externalizing, prosocial and moral behavior via changes in interpersonal strategies for emotion regulation, the threat response system, and empathy.

RESULTS

Theoretical and empirical support for the proposed mechanisms are provided.

CONCLUSIONS

The proposed mechanistic model of susceptibility to maternal sensitivity offers a novel framework of for whom and how children are affected by early maternal care, highlighting multiple reciprocal, interacting influences across genes, physiology, behavior, and the environment.

Autonomic nervous system activity predicts increasing serum cytokines in children

Systemic inflammation is associated with increased risk for prevalent and costly diseases, and animal models implicate the autonomic nervous system in the control of inflammatory processes. In humans, research on autonomic-immune connections has been much more limited, and has focused on single branch autonomic measures (i.e., either parasympathetic or sympathetic). The current study utilized cardiac autonomic balance (CAB), derived from dual-branch cardiac autonomic recordings, to test the relation between resting autonomic function and inflammatory reactivity to challenge in children.

METHODS

Participants included 96 children (51 boys, 45 girls) ages 9-11 years (mean age = 9.93 years, SD = 0.57 years). CAB values were calculated from standardized measures of parasympathetic and sympathetic activity, namely resting respiratory sinus arrhythmia and pre-ejection period data, respectively. Children provided two blood samples, one before and one following exposure to an acute social stressor or control condition. Serum was assayed for four cytokines that orchestrate inflammation: interleukin-6 (IL6), interleukin-8 (IL8), interleukin-10 (IL10), and tumor necrosis factor-alpha (TNFa).

RESULTS

We discovered large individual differences in inflammatory marker production across children, and no average main effect of stress condition. CAB significantly predicted these individual differences, such that children lower on CAB showed increasing serum cytokines from time 1 to time 2. In contrast, children with greater CAB tended to show declining inflammatory markers across the session.

DISCUSSION

Low cardiac autonomic balance (i.e., the combination of low parasympathetic and high sympathetic activity) may be a useful marker of proinflammatory tendencies in children, suggesting novel paths for early risk detection and intervention.

Feeding During Infancy: Interpersonal Behavior, Physiology, and Obesity Risk

Infancy is a sensitive developmental period that presents both opportunities and challenges for caregivers to feed their infants in ways that support healthy growth and development. The capacity to eat in a way that supports energy (caloric) intake aligned with the body's physiologic need for growth and development appear to diminish in the years following infancy, but the reasons for this and whether this is developmentally typical are unclear. Feeding interactions that undermine infants' ability to regulate their intake in response to hunger and satiety are thought to confer risk for obesity in infancy and beyond. In this integrative review, we consider what we know about the emergence of self-regulation of behavior and emotion from both a behavioral and a physiological perspective. Then, we apply this information to our emerging understanding of how self-regulation of energy intake may be derailed through feeding interactions between caregivers and infants.

Quantifying the dynamic nature of vagal responsivity in infancy: Methodological innovations and theoretical implications

According to polyvagal theory, rapid modulation of the vagal brake develops early in infancy and supports social interactions. Despite being viewed as a dynamic system, researchers typically assess vagal regulation using global measures of respiratory sinus arrhythmia (RSA; an index of vagal tone). This study sought to capture the dynamic property of RSA and evaluate individual differences in within-infant RSA responsivity during mother-infant interaction. RSA was evaluated in a sample of 135 6-month-old Mexican-American infants during a 5-min free play task. Mothers reported on their children's behavioral problems and competence at 18 months using the Brief Infant-Toddler Social and Emotional Assessment. Time-varying estimates of infant RSA during the interaction were obtained using a multiple window technique and spectrogram analysis. Using structural equation modeling, we evaluated whether within-infant SD of RSA predicted infants' behavioral problems and competence at 18 months, after adjusting for infants' mean RSA and covariates. Greater within-infant SD of RSA predicted more behavior problems at 18 months. This study demonstrates that assessing intra-individual variability in RSA, or the extent to which infants fluctuate around their average level of RSA during a task, enhances our ability to test polyvagal theory's central tenet: vagal regulation supports well-regulated social interaction.

Infant emotional responses to challenge predict empathic behavior in toddlerhood

Although emotional responses are theorized to be important in the development of empathy, findings regarding the prediction of early empathic behavior by infant behavioral and physiological responses are mixed. This study examined whether behavioral and physiological responses to mild emotional challenge (still face paradigm and car seat task) in 118 infants at age 6 months predicted empathic distress and empathic concern in response to an empathy-evoking task (i.e, experimenter's distress simulation) at age 20 months. Correlation analyses, corrected for sex and baseline levels of physiological arousal, showed that stronger physiological and behavioral responses to emotional challenge at age 6 months were positively related to observed empathic distress, but not empathic concern, at age 20 months. Linear regression analyses indicated that physiological and behavioral responses to challenge at 6 months independently predicted empathic distress at 20 months, which suggests an important role for both physiological and behavioral emotional responses in empathy development. In addition, curvilinear regression analyses showed quadratic associations between behavioral responses at 6 months, and empathic distress and empathic concern at 20 months, which indicates that moderate levels of behavioral responsivity predict the highest levels of empathic distress and empathic concern.

Attachment security in infancy predicts reduced parasympathetic reactivity in middle childhood

Children with histories of secure attachments during infancy are expected to develop healthier patterns of physiological activity at rest and in response to a stressor than children with insecure attachments. The present study examined longitudinal associations between infant attachment security and children's respiratory sinus arrhythmia (RSA) at rest and in response to a frustration task at age 9. The study focused on a sample of children referred from Child Protective Services (N = 97). RSA reflects the regulation of the parasympathetic branch of the autonomic nervous system, is sensitive to environmental influences, and is associated with emotion regulation. Children with histories of secure attachments during infancy exhibited less RSA withdrawal during a frustration task than children with histories of insecure attachments. Attachment security was not significantly associated with baseline RSA. Results suggest that mitigating parasympathetic reactivity during frustrating situations may be one avenue by which infant attachment security promotes emotion regulation.

Effects of an attachment-based intervention in infancy on children's autonomic regulation during middle childhood

The present study used a longitudinal randomized clinical trial to test whether an early intervention has causal effects on children's autonomic nervous system regulation. When children were infants, parents involved with Child Protective Services received Attachment and Biobehavioral Catch-up (ABC; N = 43), an intervention that promotes sensitive parenting, or a control intervention (N = 53). When children were 9 years old, children whose parents had received ABC exhibited higher respiratory sinus arrhythmia and lower heart rate at rest and during a parent-child interaction than children in the control group. Intervention effects were not detected for children's average skin conductance levels or for indices of autonomic reactivity. Results suggest that a parenting-focused early intervention impacted the development of children's autonomic regulation.

The impact of childhood trauma and psychophysiological reactivity on at-risk women's adjustment to parenthood

Adverse childhood experiences (ACEs) have an impact on women's adaptation to parenthood, but mechanisms are poorly understood. Autonomic nervous system reactivity was tested as a potential mediating mechanism in a sample of 193 at-risk primiparous women. ACEs were measured retrospectively during pregnancy. A baby cry-response task was administered during pregnancy while indicators of sympathetic reactivity (pre-ejection period; PEP) and parasympathetic reactivity (respiratory sinus arrhythmia; RSA) were recorded. Parenting self-efficacy, anxiety, and depressive symptoms were measured during pregnancy and 1 year after giving birth. Harsh discipline was measured 2 years after giving birth. Structural equation modeling was employed to test whether baseline PEP and RSA and reactivity mediated links between ACEs and postnatal outcomes, adjusted for prenatal variables. High ACEs predicted less RSA reactivity (p = .02), which subsequently predicted increases in depressive symptoms (p = .03). The indirect effect was not significant (p = .06). There was no indirect link between high ACEs and harsh parenting through PEP nor RSA (n = 98). The parasympathetic nervous system may be involved in negative affective responses in the transition to parenthood among women exposed to childhood trauma.