Infant Parasympathetic and Sympathetic Activity during Baseline, Stress and Recovery: Interactions with Prenatal Adversity Predict Physical Aggression in Toddlerhood

Is autonomic functioning distinctly associated with anxiety and unsociability in preschoolers?

There are many benefits of peer interactions for children's social, emotional, and cognitive development, and isolation from peers may have negative consequences for children. Although biological processes may underlie social withdrawal broadly, distinct patterns may be associated with withdrawal behaviors depending on their underlying motivation (e.g., shy versus disinterested). This study investigated the role of autonomic nervous system activity, as assessed via skin conductance level (SCL) and respiratory sinus arrhythmia (RSA) in predicting changes in unsociability (e.g., lack of interest in peers) and anxious-fearfulness (e.g., discomfort among peers). Data were collected using a community sample of 92 US preschool children (45.7% female; Mage = 45.51 months, SDage = 3.81 months) at two time points one year apart. Gender differences were also explored. Baseline physiology was assessed while viewing a neutral video clip, and reactivity was assessed while viewing social exclusion and post-aggression discussion videos. For all children, coinhibition (i.e., SCL inhibition accompanied by RSA inhibition) to the post-aggression discussion video and blunted SCL activation to the exclusion video were prospectively associated with higher levels of anxious-fearfulness one year later. For boys only, baseline reciprocal sympathetic activation (i.e., SCL activation and RSA inhibition) was prospectively related to higher levels of unsociability one year later. For girls only, RSA inhibition in response to the post-aggression discussion video was prospectively related to higher levels of unsociability one year later. Findings contribute to a growing literature on autonomic reactivity in preschoolers' adjustment and suggest possible differences in the physiological processes underlying unsociability and anxious-fearfulness.

Autonomic nervous system reactivity to emotion and childhood trajectories of relational and physical aggression

This study investigated the role of autonomic nervous system (ANS) coordination in response to emotion in girls' and boys' development of relational (e.g., ignoring, excluding) and physical (e.g., hitting, kicking) aggression. Caregivers reported on children's relational and physical aggression at ages 6, 7, 8, and 10 years (N = 232, 50.4% girls, 46.6% Latinx). Sympathetic nervous system (assessed via pre-ejection period) and parasympathetic nervous system (assessed via respiratory sinus arrhythmia) reactivity were measured in response to video clips depicting fear, happiness, and sadness at age 7. Growth curve models indicated that ANS reactivity to sadness, but not to fear or happiness, was related to trajectories of relational aggression. In contrast, ANS reactivity to all three emotions was associated with trajectories of physical aggression. Effects differed across genders, indicating that distinct patterns of ANS reactivity to emotion may be involved in girls' and boys' development of aggression. Overall, these findings contribute to a growing literature documenting the role of ANS reactivity to emotion in aggressive behavior. Moreover, this study considers ANS reactivity to specific emotions, as related to both relational and physical aggression, and as differentially expressed among girls versus boys.

Understanding emotion dysregulation from infancy to toddlerhood with a multilevel perspective: The buffering effect of maternal sensitivity

Challenges with childhood emotion regulation may have origins in infancy and forecast later social and cognitive developmental delays, academic difficulties, and psychopathology. This study tested whether markers of emotion dysregulation in infancy predict emotion dysregulation in toddlerhood, and whether those associations depended on maternal sensitivity. When children (N = 111) were 7 months, baseline respiratory sinus arrhythmia (RSA), RSA withdrawal, and distress were collected during the Still Face Paradigm (SFP). Mothers' reports of infant regulation and orientation and maternal sensitivity were also collected at that time. Mothers' reports of toddlers' dysregulation were collected at 18 months. A set of hierarchical regressions indicated that low baseline RSA and less change in RSA from baseline to stressor predicted greater dysregulation at 18 months, but only for infants who experienced low maternal sensitivity. Baseline RSA and RSA withdrawal were not significantly associated with later dysregulation for infants with highly sensitive mothers. Infants who exhibited low distress during the SFP and who had lower regulatory and orienting abilities at 7 months had higher dysregulation at 18 months regardless of maternal sensitivity. Altogether, these results suggest that risk for dysregulation in toddlerhood has biobehavioral origins in infancy but may be buffered by sensitive caregiving.

Autonomic brain functioning and age-related health concerns

The autonomic nervous system (ANS) regulates involuntary bodily functions such as blood pressure, heart rate, breathing, and digestion, in addition to controlling motivation and behavior. In older adults, the ANS is dysregulated, which changes the ability of the ANS to respond to physiological signals, regulate cardiovascular autonomic functionality, diminish gastric motility, and exacerbate sleep problems. For example, a decrease in heart rate variability, or the variation in the interval between heartbeats, is one of the most well-known alterations in the ANS associated with health issues, including cardiovascular diseases and cognitive decline. The inability to perform fundamental activities of daily living and compromising the physiological reactivity or motivational responses of older adults to moving toward or away from specific environmental stimuli are significant negative consequences of chronic and geriatric conditions that pose grave threats to autonomy, health, and well-being. The most updated research has investigated the associations between the action responsiveness of older adults and the maintenance of their physiological and physical health or the development of mental and physical health problems. Once autonomic dysfunction may significantly influence the development of different age-related diseases, including ischemic stroke, cardiovascular disease, and autoimmune diseases, this review aimed to assess the relationship between aging and autonomic functions. The review explored how motivational responses, physiological reactivity, cognitive processes, and lifelong developmental changes associated with aging impact the ANS and contribute to the emergence of health problems.

Parental sensitivity modifies the associations between maternal prenatal stress exposure, autonomic nervous system functioning and infant temperament in a diverse, low-income sample

Evidence suggests that adversity experienced during fetal development may shape infant physiologic functioning and temperament. Parental sensitivity is associated with child stress regulation and may act as a buffer against risk for intergenerational health effects of pre- or postnatal adversity. Building upon prior evidence in a racially and ethnically diverse sample of infants (M infant age = 6.5 months) and women of low socioeconomic status, this study examined whether coded parenting sensitivity moderated the association between an objective measure of prenatal stress exposures (Stressful Life Events (SLE)) and infant parasympathetic (respiratory sinus arrhythmia; RSA) or sympathetic (pre-ejection period; PEP) nervous system functioning assessed during administration of the Still-Face-Paradigm (SFP) (n = 66), as well as maternal report of temperament (n = 154). Results showed that parental sensitivity moderated the associations between prenatal stress exposures and infant RSA reactivity, RSA recovery, PEP recovery, and temperamental negativity. Findings indicate that greater parental sensitivity is associated with lower infant autonomic nervous system reactivity and greater recovery from challenge. Results support the hypothesis that parental sensitivity buffers infants from the risk of prenatal stress exposure associations with offspring cross-system physiologic reactivity and regulation, potentially shaping trajectories of health and development and promoting resilience.

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.

Unique Contributions of Maternal Prenatal and Postnatal Emotion Dysregulation on Infant Respiratory Sinus Arrhythmia

Prenatal intrauterine exposures and postnatal caregiving environments may both shape the development of infant parasympathetic nervous system (PNS) activity. However, the relative contributions of prenatal and postnatal influences on infant respiratory sinus arrhythmia (RSA)-an index of PNS functioning-are relatively unknown. We examined whether prenatal and postnatal maternal emotion dysregulation, a transdiagnostic construct that spans mental health diagnoses, were independently related to infant RSA trajectories during a social stressor, the still-face paradigm. Our sample included 104 mothers and their 7-month-old infants. Maternal emotion dysregulation was measured with the Difficulties in Emotion Regulation Scale during the 3rd trimester of pregnancy and again at a 7-month postpartum laboratory visit. Infant RSA was recorded during the still-face paradigm. Only postnatal maternal emotion dysregulation was associated with infant RSA. Specifically, high postnatal emotion dysregulation was associated with a blunted (i.e., dampened reactivity and recovery) infant RSA response profile. Infant sex did not moderate the associations between maternal emotion dysregulation and infant RSA. Findings suggest that postnatal interventions to promote effective maternal emotion regulation may reduce risk for infants' dysregulated psychophysiological stress responses.

Patterns of adversity and post-traumatic stress among children adopted from care

BACKGROUND

Children adopted from care are more likely to have experienced early adversity, but little is known about the impact of early adversity on later post-traumatic stress (PTS) symptoms.

OBJECTIVE

To investigate sub-groups of adversity in a sample of adopted children and examine the association with later PTS symptoms.

PARTICIPANTS AND SETTING

A study of British children adopted from care using social worker records (N = 374) and questionnaire-based longitudinal study of n = 58 children over 4-years post adoptive placement.

METHODS

We used latent class analysis to identify subgroups of children based on commonalities in perinatal and postnatal adversity experienced prior to adoption and examined differences in PTS symptoms at 4-years post-placement between subgroups.

RESULTS

Nearly one in five (19 %) children were in the clinical or borderline ranges for symptoms of PTS arousal, 14 % for PTS avoidance and 8 % for PTS intrusion. The 5-class solution fitted the data best, with one class characterized by children with a low probability of experiencing any adversity, one perinatal adversity class and three classes capturing different patterns of adversity. The multiple complex adversity class involving both perinatal and postnatal adversity had significantly higher symptoms of PTS avoidance and arousal than other sub-groups.

CONCLUSIONS

The prevalence and complexity of PTS symptoms among adoptive children highlights the need for effective interventions considering different profiles of early adversity.

Developmental foundations of physiological dynamics among mother-infant dyads: The role of newborn neurobehavior

This study tested whether newborn attention and arousal provide a foundation for the dynamics of respiratory sinus arrhythmia (RSA) in mother-infant dyads. Participants were 106 mothers (M_age  = 29.54) and their 7-month-old infants (55 males and 58 White and non-Hispanic). Newborn attention and arousal were measured shortly after birth using the NICU Network Neurobehavioral Scale. Higher newborn arousal predicted a slower return of infant RSA to baseline. Additionally, greater newborn attention predicted mothers' slower return to baseline RSA following the still-face paradigm, and this effect only held for mothers whose infants had lower newborn arousal. These findings suggest that newborn neurobehavior, measured within days of birth, may contribute to later mother-infant physiological processes while recovering from stress.

Neonatal brain and physiological reactivity in preschoolers: An initial investigation in an Asian sample

Parasympathetic nervous system (PNS) activity is important to physiological regulation. Limbic structures are important in determining what information the PNS receives, potentially influencing concurrent physiological responsivity and, ultimately, shaping PNS development. Yet, whether individual differences in these structures are linked to PNS activity in early childhood remains unclear. Here, in an exploratory capacity, we examined the association between neonatal limbic structures (i.e., the left and right amygdala and hippocampus) and preschoolers' resting-state respiratory sinus arrhythmia (RSA). RSA is a measure of heart-rate variability, a physiological marker that reflects fluctuation in the PNS and is often found predictive of emotion regulation and psychological wellbeing. Data were extracted from the "Growing Up in Singapore towards Healthy Outcomes" (GUSTO) cohort (n = 73, 39 girls). Neonatal limbic volume was collected within two weeks after birth while infants were asleep. Resting-state RSA was collected during a coloring session at 42 months of age. After controlling for potential confounders, a Bonferroni-corrected significant association between neonatal left hippocampal volume and resting-state RSA emerged wherein larger hippocampal volume was associated with higher resting-state RSA. No significant associations were present between resting-state RSA and right or left amygdala, or right hippocampal volume. These findings contribute to an increasing body of evidence aiming at enhancing our understanding of neurobiological underpinnings of parasympathetic activity and modulation. Results are also discussed with reference to ideas concerning biological sensitivity to context, as both left hippocampal volume and resting-state RSA were previously found to moderate associations between adversity and psychological function.

Heart Rate and Skin Conductance Associations with Physical Aggression, Psychopathy, Antisocial Personality Disorder and Conduct Disorder: An Updated Meta-Analysis

The associations between physiological measures (i.e., heart rate and skin conductance) of autonomic nervous system (ANS) activity and severe antisocial spectrum behavior (AB) were meta-analyzed. We used an exhaustive partitioning of variables relevant to the ANS-AB association and investigated four highly relevant questions (on declining effect sizes, psychopathy subscales, moderators, and ANS measures) that are thought to be transformative for future research on AB. We investigated a broad spectrum of physiological measures (e.g., heart rate (variability), pre-ejection period) in relation to AB. The search date for the current meta-analysis was on January 1^st, 2020, includes 101 studies and 769 effect sizes. Results indicate that effect sizes are heterogeneous and bidirectional. The careful partitioning of variables sheds light on the complex associations that were obscured in previous meta-analyses. Effects are largest for the most violent offenders and for psychopathy and are dependent on the experimental tasks used, parameters calculated, and analyses run. Understanding the specificity of physiological reactions may be expedient for differentiating between (and within) types of AB.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

ETHICS AND DISSEMINATION

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

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.

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.

Reduced caregiving quality measured during the strange situation procedure increases child's autonomic nervous system stress response

BACKGROUND

Dysfunctional maternal behavior has been shown to lead to disturbances in infant's regulatory capacities and alterations in vagal reactivity. We aim to investigate the autonomic nervous system (ANS) response of the child during the strange situation procedure (SSP) in relation to the quality of maternal behavior.

METHODS

Twelve month after birth, 163 mother-child-dyads were investigated during the SSP. Heart rate (HR) and both, the parasympathetic branch (PNS) via the respiratory sinus arrhythmia (RSA) and the sympathetic branch (SNS) via the left ventricular ejection time (LVET) of the ANS were continuously determined during the SSP using electrocardiogram (ECG) and impedance cardiogram (ICG) measures. Maternal behavior was assessed by using the AMBIANCE measure.

RESULTS

The ANS response in infants of mothers with disruptive behavior compared to infants of non-disruptive mothers was significantly altered during the SSP: HR increased especially when infants of disruptive mothers were alone with the stranger (F (1, 161) = 4.15, p = .04) with a significant vagal withdrawal when being in contact with the stranger despite of presence of the mother (F (1, 161) = 5.11, p = .03) and a significant increase in vagal tone during final reunion (F (1, 161) = 3.76, p = .05). HR increase was mainly based on a decrease in LVET (F (1, 161) = 4.08, p = .05) with a maximum infant's HR when the stranger came into the room instead of the mother.

CONCLUSION

Both, SNS and PNS branches of the child are significantly altered in terms of an ANS imbalance, especially during contract to a stranger, in relation to dysfunctional maternal behavior. Our findings suggest the importance of supporting high quality caregiving that enables the infant to adapt adequately to stressful interpersonal situations which is likely to promote later health.

Emotion regulation strategy knowledge moderates the link between cumulative stress and anxiety symptoms in childhood

Experiencing chronic stress early in life has been linked to anxiety symptoms and related outcomes. This study examined whether emotional self-regulatory processes, specifically children’s awareness of emotion regulation strategies, would qualify the link between cumulative stress and anxiety symptoms in childhood. One hundred and twenty-nine 6- to 11-year-olds ( M = 8.84; SD = 1.61; 47% girls) participated in the study. We derived an index of nine environmental stressors and quantified children’s emotion regulation strategy awareness from an interview about their emotional experiences. Parents reported on children’s anxiety symptoms. As expected, cumulative stress was positively associated with anxiety symptoms. Emotion regulation strategies moderated the effect of cumulative stress on anxiety symptoms, such that children with larger repertoires had fewer symptoms in the context of low stress, but more symptoms in the context of high stress. Results offer new insight in understanding anxiety symptoms in childhood and demonstrate the importance of children’s emotion regulation strategy knowledge as a novel facet of regulatory skill that may characterize the specific emotion dysregulation implicated in the emergence of psychopathology.

Small intra-individual variability of the pre-ejection period justifies the use of pulse transit time as approximation of the vascular transit

Background

Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT.

Methods

PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus.

Results

Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0–5.9 ms, 2) 2.8–5.1 ms, and 3) 1.6–12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236).

Conclusion

In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.