Test-Retest Reliability of Pediatric Heart Rate Variability: A Meta-Analysis

Cognitive control processes and emotion regulation in adolescence: Examining the impact of affective inhibition and heart-rate-variability on emotion regulation dynamics in daily life

Cognitive control processes likely influence the extent to which adolescents can successfully regulate their emotions. This study examined whether individual differences in affective inhibition and heart rate variability (HRV), as a peripheral index of cognitive control, moderated the association between momentary emotion regulation and negative affect (NA). Ecological Momentary Assessments (EMA) over 14 days were obtained in 235 adolescents (Mage = 13.48 years; 106 females). At each assessment, participants reported their current NA and the extent to which they used cognitive reappraisal and rumination. Moreover, at three time points (approximately 1 year, 6 months, and just before the EMA), affective inhibition was assessed using an affective go/no-go task and HRV was recorded at rest. Results indicate that adolescents with lower affective inhibition reported lower average levels of daily rumination. However, affective inhibition did not moderate the association between either daily cognitive reappraisal or rumination and momentary NA. Consistent with hypotheses, the association between momentary rumination and NA was weaker in adolescents showing higher levels of resting HRV. Overall, findings may underscore the importance of interventions targeting HRV as a malleable factor for enhancing adolescents' affective well-being.

Reliability of an "At-Home" Method for Monitoring Resting and Reactive Autonomic Nervous System Activity in Children: A Pilot Study

BACKGROUND

Heart rate variability (HRV), an index of the functional status of the autonomic nervous system (ANS), provides an opportunity for early detection of ANS dysfunction. Lower resting, vagally related HRV parameters are associated with increased risk of physical and mental illness. External factors influencing the ANS, such as the testing environment, may impact the interpretation of HRV. This study's main aim was to determine the reliability of HRV resting and reactivity tests performed at home with children aged 4-9 years.

METHODS

Fourteen healthy children (female n = 8) aged 6.8 ± 1.5 years participated. Two HRV tests were performed at home via online supervision 7 days apart using a Polar H10 heart rate monitor. The absolute and relative reliability of the pre-exercise resting (5 min) and sub-maximal exercise step test recovery (4 × 30 s segments) HRV time and frequency domains were calculated.

RESULTS

The Pearson correlation coefficients for day 1 versus day 7 for the vagal activity HRV domains (RMSSD log) at rest and in the first 30 s and 30-60 s of recovery indicated good-to-excellent relative reliability (r > 0.8, p < 0.01). Absolute reliability was moderate for the resting RMSSD log, with a coefficient of variation (CV) of 5.2% (90% CI: 3.9, 7.8%), high for the first 30 s of standing recovery, with a CV of 10.7% (90% CI: 8.2, 15.7%), and moderate for 30-60 s of recovery, with a CV of 8.7% (90% CI: 6.6, 12.9%).

CONCLUSIONS

The findings of this pilot study indicate that the resting and exercise recovery HRV measures of vagal activity can be measured reliably at home in children. This represents a novel "at-home" protocol for monitoring ANS health and development in children.

Examining the feasibility and utility of heart rate variability on intervention outcomes targeting emotion regulation in autism: a brief report

Autistic youth experience several behavioral and emotional characteristics that can predispose them to emotion dysregulation (ED). Current literature examining ED in autism spectrum disorder (ASD) is limited to parent- and self-reported measures, indicating a need for biological or physiological methods to better assess emotion regulation in ASD. Utilizing the autonomic nervous system, specifically heart rate variability (HRV), may be a promising method to objectively measure ED in ASD, given it is one of the body's primary means of regulating physiological arousal. Our pilot study is one of the first to examine the feasibility, utility, and construct validity of HRV along with clinical measures within an intervention targeting ED-specific symptoms in ASD. Participants included 30 autistic youth ages 8-17 years who participated in the pilot study of Regulating Together, a group-based intervention targeting emotion regulation. We demonstrate HRV is feasible, demonstrates adequate test-retest reliability, and is complimentary to clinician- and parent-reported measures. Our preliminary findings also point to certain HRV profiles being indicative of long-term outcomes after receiving treatment. HRV may be a useful, objective tool in determining differential needs of long-term follow-up care for treatment maintenance at screening or baseline stages.

rTMS in mental health disorders

Transcranial magnetic stimulation (TMS) is an innovative and non-invasive technique used in the diagnosis and treatment of psychiatric and neurological disorders. Repetitive TMS (rTMS) can modulate neuronal activity, neuroplasticity and arousal of the waking and sleeping brain, and, more generally, overall mental health. Numerous studies have examined the predictors of the efficacy of rTMS on clinical outcome variables in various psychiatric disorders. These predictors often encompass the stimulated brain region's location, electroencephalogram (EEG) activity patterns, potential morphological and neurophysiological anomalies, and individual patient's response to treatment. Most commonly, rTMS is used in awake patients with depression, catatonia, and tinnitus. Interestingly, rTMS has also shown promise in inducing slow-wave oscillations in insomnia patients, opening avenues for future research into the potential beneficial effects of these oscillations on reports of non-restorative sleep. Furthermore, neurophysiological measures emerge as potential, disease-specific biomarkers, aiding in predicting treatment response and monitoring post-treatment changes. The study posits the convergence of neurophysiological biomarkers and individually tailored rTMS treatments as a gateway to a new era in psychiatric care. The potential of rTMS to induce slow-wave activity also surfaces as a significant contribution to personalized treatment approaches. Further investigations are called for to validate the imaging and electrophysiological biomarkers associated with rTMS. In conclusion, the potential for rTMS to significantly redefine treatment strategies through personalized approaches could enhance the outcomes in neuropsychiatric disorders.

Cardiovascular reactivity as a measure of irritability in a transdiagnostic sample of youth: Preliminary associations

OBJECTIVES

Irritability is a transdiagnostic symptom in developmental psychopathology, conceptualized as a low threshold for frustration and increased proneness to anger. While central to emotion regulation, there is a vital need for empirical studies to explore the relationship between irritability and underlying physiological mechanisms of cardiovascular arousal.

METHODS

We examined the relationship between irritability and cardiovascular arousal (i.e., heart rate [HR] and heart rate variability [HRV]) in a transdiagnostic sample of 51 youth (M = 12.63 years, SD = 2.25; 62.7% male). Data was collected using the Empatica E4 during a laboratory stop-signal task. In addition, the impact of motion activity, age, medication, and sleep on cardiovascular responses was explored.

RESULTS

Main findings showed that irritability was associated with increased HR and decreased HRV during task performance.

CONCLUSIONS

Findings support the role of peripheral physiological dysregulation in youth with emotion regulation problems and suggest the potential use of available wearable consumer electronics as an objective measure of irritability and physiological arousal in a transdiagnostic sample of youth.

Estimating Resting HRV during fMRI: A Comparison between Laboratory and Scanner Environment

Heart rate variability (HRV) is regularly assessed in neuroimaging studies as an indicator of autonomic, emotional or cognitive processes. In this study, we investigated the influence of a loud and cramped environment during magnetic resonance imaging (MRI) on resting HRV measures. We compared recordings during functional MRI sessions with recordings in our autonomic laboratory (LAB) in 101 healthy subjects. In the LAB, we recorded an electrocardiogram (ECG) and a photoplethysmogram (PPG) over 15 min. During resting state functional MRI, we acquired a PPG for 15 min. We assessed anxiety levels before the scanning in each subject. In 27 participants, we performed follow-up sessions to investigate a possible effect of habituation. We found a high intra-class correlation ranging between 0.775 and 0.996, indicating high consistency across conditions. We observed no systematic influence of the MRI environment on any HRV index when PPG signals were analyzed. However, SDNN and RMSSD were significantly higher when extracted from the PPG compared to the ECG. Although we found a significant correlation of anxiety and the decrease in HRV from LAB to MRI, a familiarization session did not change the HRV outcome. Our results suggest that psychological factors are less influential on the HRV outcome during MRI than the methodological choice of the cardiac signal to analyze.

Heart rate variability improves in 3-5-year-old children following a 6-month physical activity-based intervention: the Active Early Learning (AEL) cluster randomised controlled trial

Heart rate variability (HRV) measurement provides non-invasive assessment of autonomic stability and cardiometabolic disease risk. Insufficient physical activity in early childhood may contribute to negative cardiometabolic health. The Active Early Learning (AEL) study was a 6-month randomised controlled trial investigating the effects of a physical activity-based program incorporating movement within the daily curriculum of preschool children. The current study assessed the effects of the AEL intervention on HRV as a measure of cardiac vagal control. Children aged between 3-5 years and enrolled in a preschool with an attendance of ≥15 children were eligible. Physical activity was recorded using an Actigraph wGT3x accelerometer worn at the waist of participants over 3 consecutive days. A Polar H10 chest strap measured HRV with the HF-band and RMSSD representing cardiac vagal control. After 6 months of the AEL trial, linear mixed model analyses revealed a significant intervention effect for increased HF (p = 0.044). The control group did not demonstrate changes in cardiac vagal control after the intervention ceased. Independent of age, sex, physical activity and BMI, the AEL study elicited significant improvements in the cardiac vagal control of participants who received the intervention. Findings highlight the importance of investigating HRV for assessing the cardiometabolic health in young children. ANZCTR trial registration number: ACTRN12619000638134. Novelty: The AEL curriculum improved child HRV independent of age, sex, physical activity and BMI. Heart rate and RR intervals did not demonstrate changes for the intervention and control groups. Multivariate programs for developing physical competence, confidence, knowledge and motivation may improve child health.

On the Variability of Heart Rate Variability-Evidence from Prospective Study of Healthy Young College Students

Heart rate variability (HRV) has been widely used as indices for autonomic regulation, including linear analyses, entropy and multi-scale entropy based nonlinear analyses, and however, it is strongly influenced by the conditions under which the signal is being recorded. To investigate the variability of healthy HRV under different settings, we recorded electrocardiograph (ECG) signals from 56 healthy young college students (20 h for each participant) at campus using wearable single-lead ECG device. Accurate R peak to R peak (RR) intervals were extracted by combing the advantages of five commonly used R-peak detection algorithms to eliminate data quality influence. Thorough and detailed linear and nonlinear HRV analyses were performed. Variability of HRV metrics were evaluated from five categories: (1) different states of daily activities; (2) different recording time period in the same day during free-running daily activities; (3) body postures of sitting and lying; (4) lying on the left, right and back; and (5) gender influence. For most of the analyzed HRV metrics, significant differences (p < 0.05) were found among different recording conditions within the five categories except lying on different positions. Results suggested that the standardization of ECG data collection and HRV analysis should be implemented in HRV related studies, especially for entropy and multi-scale entropy based analyses. Furthermore, this preliminary study provides reference values of HRV indices under various recording conditions of healthy young subjects that could be useful information for different applications (e.g., health monitoring and management).

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.

Heart rate variability for determining autonomic nervous system effects of lifestyle behaviors in early life: A systematic review

BACKGROUND

An unhealthy lifestyle negatively alters autonomic nervous system (ANS) activity as reflected by decreased heart rate variability (HRV), increasing cardiovascular disease (CVD) risk. Research investigating the effect of modifiable lifestyle factors on ANS activity in young children is limited. Early identification of these risk factors is vital to improving long-term individual and public health outcomes. A systematic review was conducted to assess the effect of maternal or child modifiable lifestyle factors on child ANS activity.

METHODS

Following the 2009 PRISMA guidelines, three electronic databases were searched from February 2018 - July 2019 for articles describing human trials between 1996 - 2019. Included studies examined ANS activity of children between 28 weeks gestational age - 6 years in relation to modifiable lifestyle CVD risk factors.

RESULTS

Twenty-six studies fulfilled inclusion criteria. Sixteen studies reported that modifiable lifestyle factors significantly influenced the HRV of children. Increased HRV was significantly associated with higher maternal zinc and omega-3 fatty acid intake, regular maternal aerobic exercise and a non-smoking environment. Child diet and body composition demonstrated some support for an association between these modifiable lifestyle factors and child HRV.

CONCLUSION

There is cross-sectional evidence supporting an association between maternal lifestyle factors and child HRV. Evidence is less supportive of a relationship between child modifiable lifestyle factors and child HRV. Monitoring the effects of lifestyle interventions on the ANS via HRV measurements of both mother and child may identify child CVD risk.

Measuring Heart Rate Variability Using Commercially Available Devices in Healthy Children: A Validity and Reliability Study

Heart rate variability (HRV) is an accepted method for determining autonomic nervous system activity and cardiovascular risk in various populations. This study assessed the validity and reliability of a commercially available finger photoplethysmography (PPG) system for measuring pediatric HRV in a real-world setting. Sixteen healthy children (4.06 ± 0.58 years) were recruited. The PPG system was compared to the Polar H10 heart rate (HR) sensor validated against ECG (gold standard) for HRV measurement. Seated short-term resting R-R intervals were recorded simultaneously using both systems. Recordings were performed on 3 days at the participants’ school. Paired t-tests, effect sizes and Bland–Altman analyses determined the validity of the PPG system. The relative and absolute reliability of both systems were calculated. No HRV parameters were valid for the PPG system. Polar H10 yielded moderate (0.50–0.75) to good (0.75–0.90) relative reliability with R-R intervals and the standard deviation of instantaneous and continuous R-R variability ratio showing the best results (ICCs = 0.84). Polar H10 displayed better absolute reliability with the root mean square of successive differences, R-R intervals and HR showing the lowest values (TEM% < 12%). The use of the Polar H10 and not the PPG system is encouraged for HRV measurement of young children in an educational real-world setting.

Sex differences in adolescents' cardiac reactivity and recovery under acute stress: The importance of nonlinear measures

How well adolescents can self-regulate in the face of stressors has considerable implications for long-term well-being and risk of psychopathology. This study investigated sex differences in adolescents' cardiac reactivity and recovery during a stressful task. Measures of cardiac variability (linear) and complexity (nonlinear) were obtained from N = 92 adolescents, 41 males (M age = 13.28, SD = 0.69; BMI = 21.9) and 51 females (M age = 13.36, SD = 0.67; BMI = 21.5). The adolescents underwent the Trier Social Stress Test, consisting of five conditions: baseline, anticipation, social exposure, math task, and recovery. Repeated measures ANOVAs revealed that female in comparison to male adolescents showed lower cardiac complexity revealed by higher short-term scaling exponent at baseline (p = .006) and math (p = .013) and lower entropy at exposure (p = .013) and math (p = .012). A marginal between-groups effect was found for Higuchi's fractal dimension, F(1, 90) = 3.67, p = .059, η_p ²  = .041, with females showing lower fractal dimension than males in math (p = .037). Linear measures did not reveal sex-related differences. Results suggest that adolescent females show lower cardiac complexity during stress. These findings support the importance of nonlinear cardiac measures for understanding cardiac reactivity during stress. Further research is needed to test the hypothesis that cardiac complexity is useful to detect an increased risk of emotional disorders, disorders that are more prevalent in women.

Reactive Heart Rate Variability and Cardiac Entropy in Children with Internalizing Disorder and Healthy Controls

Atypical vagal reactivity has been linked to internalizing psychopathology and less adaptive emotion regulation, but reactive cardiac entropy is largely unexplored. Therefore, this study investigated reactive vagally-mediated heart-rate variability (vmHRV) and cardiac entropy in relation to emotion regulation. Electrocardiograms of 32 children (9-13 years) with internalizing difficulties and 25 healthy controls were recorded during a baseline and a sad film. Reactivity-measures were calculated from the root mean square of successive differences (RMSSD) and sample entropy (SampEn). Emotion regulation was assessed using the emotion regulation checklist (ERC). Determinants of reactive SampEn and RMSSD were analyzed with marginal and generalized linear models. The study also modeled the relationship between cardiac reactivity and emotion regulation while controlling for psychopathology. The two groups differed significantly in vmHRV-reactivity, with seemingly higher vagal-withdrawal in the control group. SampEn increased significantly during the film, but less in subjects with higher psychopathology. Higher reactive entropy was a significant predictor of better emotion regulation as measured by the ERC. Internalizing subjects and controls showed significantly different vmHRV-reactivity. Higher reactive cardiac entropy was associated with lower internalizing psychopathology and better emotion regulation and may reflect on organizational features of the neurovisceral system relevant for adaptive emotion regulation.

Infant Vagal Tone and Maternal Depressive Symptoms: A Bottom-Up Perspective

Children vary in their susceptibility to environmental exposures such as maternal depression, but little is known about how children shape those same environments. When raising an infant with low arousal, mothers at risk of depression may experience decreased parenting self-efficacy and increased depressive symptoms. We evaluated a longitudinal mediated moderation model that hypothesized interactive effects of infant vagal tone (indexed by respiratory sinus arrhythmia [RSA]) and maternal postpartum depressive (PPD) symptoms on maternal depressive symptoms in early childhood via parenting self-efficacy. Among a sample of 322 very low-income Mexican American mother-infant dyads (46% male infants), infant RSA was assessed at 6 weeks of age; mothers (M_age = 27.8, SD = 6.5) reported PPD symptoms every 3 weeks from 6 weeks to 6 months, parenting self-efficacy at 18 and 24 months, and depressive symptoms at 18 and 36 months. Higher PPD symptoms predicted higher maternal depressive symptoms at 36 months, especially among mothers whose infants had lower resting RSA. The interactive effect of PPD symptoms and infant RSA on 36-month depressive symptoms was partially mediated by lower parenting self-efficacy. Lower infant RSA may exacerbate the detrimental effects of PPD symptoms on subsequent maternal well-being via damage to mothers' beliefs in their ability to parent effectively.

The Association Between Heart Rate Variability and Neurocognitive and Socio-Emotional Development in Nepalese Infants

BACKGROUND

Many young children in developing countries do not reach their developmental potential. Traditional methods for assessing developmental outcome are time consuming, thus, physiological measures that can contribute to the prediction of developmental outcomes in high risk groups have been suggested. Vagally mediated heart rate variability (vmHRV) is considered a neurophysiological or peripheral proxy for prefrontal and executive functioning and might serve as a supplement for traditional measurements of developmental status and as a potential useful risk indicator.

AIM

In the present study, we wanted to describe the vmHRV in Nepalese infants and relate it to the Bayley Scales of infant and toddler development, 3. edition (Bayley-III) subscales.

METHODS

600 Nepalese infants were included in the study. At 6-11 and 17-24 months, we measured neurodevelopmental and socio-emotional outcomes by the Bayley-III. Inter-beat intervals were recorded at two measurement points when the children were 17-24 months.

RESULTS

There was a high intraclass correlation between HRV indices generated from the two measurement points. No significant associations between vmHRV and Bayley-III sub scales were found at any time.

CONCLUSION

This study is the first to describe vmHRV in healthy infants and the relationship between Bayley-III scores. Our results suggest that vmHRV is not associated with measures of general development in infancy.

Exercise and Arterial Modulation in Children: The EXAMIN YOUTH Study

Background: Cardiovascular disease (CVD) remains to be one of the most frequent causes of death worldwide. Cardiovascular (CV) risk factors such as hypertension and obesity often manifest in childhood. The study examines the associations of blood pressure, body mass index and physical activity with cardiopulmonary, metabolic, and psychosocial health of children in a systems physiology approach. Methods/Design: This cross-sectional study will be performed in a cohort of 6 to 8 year old school children (n = 1000). As a measure of vascular health, retinal microvascular diameters and large artery pulse wave velocity will be examined. Anthropometric parameters, such as weight, height, body mass index, and blood pressure will be assessed according to standardized protocols for children. Physical fitness and activity will be measured by a 20 m shuttle run, a 20 m sprint and a proxy-reported questionnaire on lifestyle behavior. Spirometry, assessment of heart rate variability and skin advanced glycation end products as well as a flanker test will be performed to determine systemic end organ alterations. Discussion: The study offers a unique integrative primary prevention concept that aims to set the grounds for a healthy and active lifestyle approach during childhood. It will help optimize CV risk stratification to identify children at risk of disease progression later in life. The study will demonstrate the importance of specific CV screening programs in children to reduce the growing burden of CV disease in adulthood. Prospective follow-up studies will have to prove the efficacy of primary prevention programs in children to achieve healthier aging as a long-term goal.

Stress reactivity in healthy child offspring of parents with anxiety disorders

Several studies suggest that anxiety disorders (AD) involve dysregulation of the autonomic nervous system (ANS) and hypothalamic-pituitary (HPA) axis. However, it is unknown if alterations in these biological systems are premorbid markers of AD risk or a state-dependent feature of anxiety. This study examined ANS and HPA-axis response to a laboratory stressor in healthy child offspring of parents with (n = 55) and without (n = 98) a history of AD. High frequency heart rate variability (HF-HRV) was assessed during sitting and standing baseline conditions and during a speech task where participants remained standing. Salivary cortisol was measured at baseline and at 15, 30, 45 and 60 min post-speech. Subjective anxiety was assessed with a visual analogue scale. Children of parents with AD displayed reduced HRV and a blunted cortisol response to the speech task compared to children of non-anxious parents. No risk group effect was found for anxiety ratings. These preliminary data suggest that healthy children of anxious parents exhibit altered stress reactivity to an acute laboratory stressor. Further research is needed to confirm findings and identify mechanisms that may account for altered self-regulation processes to a stressor in children at familial risk for AD.

Heart rate mean and variability as a biomarker for phenotypic variation in preschoolers with autism spectrum disorder

Interest in autonomic arousal in autism spectrum disorder (ASD) is increasing; however, reliability of these measures in ASD is unknown, and previously reported associations with social and cognitive abilities are inconsistent. This study assesses heart rate (HR) and HR variability (HRV) in preschoolers with ASD or typical development (TD) while they passively watched naturalistic videos. Measurement reliability, group differences, and the relationship with social and cognitive abilities were evaluated. Seventy one ASD and 66 TD children (2-4 years) provided cardiac data from two sessions. Test-retest intraclass correlations of HR and HRV over a 3-week period were moderate to good in both groups. Groups did not differ in mean level of HR or HRV. Intra-individual variability of HR between video segments within a session was higher in the ASD group, but intraclass correlations of this metric were low. Higher HR related to better language skills in TD children, but not after accounting for age and nonverbal ability. Higher HRV related to better expressive and receptive language in ASD children after controlling for age and nonverbal ability. HR/HRV were not related to social or executive functioning skills and did not explain any additional variance in abilities at a 12-month follow-up visit. In summary, variation in language abilities is associated with HR in the TD group and HRV in the ASD group. While preliminary, these results are promising for consideration of autonomic control as a biomarker for individual differences in ASD and may help us understand the mechanisms that contribute to communication skills. Autism Research 2019, 12: 39-52. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Cardiac activity, such as heart rate and heart rate variability, is linked to a wide range of psychological functions. This study shows that there is an association between heart rate and heart rate variability and language skills in young children with autism spectrum disorder (ASD). These results may help us understand what underlies individual differences in developmental abilities in young children with ASD.

The relationship between maternal responsivity, socioeconomic status, and resting autonomic nervous system functioning in Mexican American children

Adversity, such as living in poor socioeconomic conditions during early childhood, can become embedded in children's physiology and deleteriously affect their health later in life. On the other hand, maternal responsivity may have adaptive effects on physiology during early childhood development. The current study tested both the additive and interactive effects of socioeconomic status (SES) and maternal responsivity measured at 1year of age on resting autonomic nervous system (ANS) function and trajectory during the first 5years of life. Participants came from a birth cohort comprised of Mexican-origin families living in California. Children's resting ANS functioning (respiratory sinus arrhythmia; RSA; pre-ejection period; PEP; and heart rate; HR) was collected at 1, 3.5, and 5years of age (N=336) and modeled across time using Hierarchical Linear Modeling. Consistent with hypotheses, results showed that low SES predicted flatter trajectories of resting HR and PEP over early childhood (i.e., patterns of consistently higher heart rate; shorter PEP), whereas children who experienced positive maternal responsivity had steeper trajectories in RSA and PEP over time (i.e., increasing parasympathetic activation; decreasing sympathetic activation). The interaction between SES and maternal responsivity significantly predicted RSA intercept at age 5, such that among children living in low SES environments, high maternal responsivity mitigated the negative effect of poverty and predicted higher resting RSA at 5years of age. Results are consistent with the early life programming theory that suggests that environmental influences become biologically embedded in the physiology of children living in socially disadvantaged contexts, and identify increased maternal responsivity as a developmental mechanism that could offset the deleterious effects of low SES.