Cardiac vagal regulation in infancy predicts executive function and social competence in preschool: Indirect effects through language

From terrible twos to sassy sixes: The development of vocabulary and executive functioning across early childhood

Across the early childhood period of development, young children exhibit considerable growth in their executive functioning (EF) and vocabulary abilities. Understanding the developmental trajectory of these seemingly interrelated processes is important as both early vocabulary and EF have been shown to predict critical academic and socio-emotional outcomes later in childhood. Although previous research suggests that EF and vocabulary are correlated in early childhood, much of the existing longitudinal research has focused on unidirectional relations among preschool child samples. The current large-scale study, therefore, sought to examine whether children's vocabulary and EF abilities are bidirectionally related over time across four measurement waves in early childhood (i.e., at ages 2, 3, 4, and 6). At each timepoint, children's vocabulary skills were positively correlated with their concurrent EF abilities. After controlling for child sex and maternal education status, the best-fitting, cross-lagged panel model was a unidirectional model whereby children's early vocabulary scores predicted their later EF performance at each timepoint. Although age 2 EF significantly predicted age 3 vocabulary size, this association was no longer significant after accounting for maternal education status. Our results illustrate that vocabulary size plays an important role in predicting children's later EF performance across various timepoints in early childhood, even after controlling for children's initial EF scores. These findings have important implications for intervention research as fostering early vocabulary acquisition may serve as a possible avenue for improving EF outcomes in young children. RESEARCH HIGHLIGHTS: Children's vocabulary size is positively correlated with their concurrent executive functioning skill at ages 2, 3, 4, and 6 Young children's early vocabulary scores predict their later EF performance across measurement waves, even after controlling for initial EF skill There is stability in children's relative vocabulary size and executive functioning performance over time in early childhood.

The longitudinal contributions of child language, negative emotionality, and maternal positive affect on toddler executive functioning development

Executive functions (EF) develop rapidly across early childhood and play a prominent role in promoting adaptive outcomes later in development. Although the existing literature suggests that the development of early EF is sensitive to the influence of intrinsic and extrinsic factors, limited research has examined the joint contributions of multiple child and contextual factors in infancy/toddlerhood. The purpose of our longitudinal study was therefore to identify early environmental, behavioral, biologically-based factors that influence children's EF outcomes in late toddlerhood. Participants included 409 mother-child dyads (209 girls) and the data was collected across children's first three postnatal years. Parent-report measures were used to assess infant negative affectivity (5-months; IBQ-R) and toddler language (age 2; MCDI), and both maternal positive affect (5-months) and toddler frustration (age 2) were coded during mother-child interaction tasks. A battery of behavioral tasks was used to measure child EF in late toddlerhood (age 3). After controlling for maternal education (a proxy for children's socio-economic environment), path analysis indicated that both infant and maternal affect at 5-months directly predicted toddlers' language skills and frustration expression at age 2. Toddler language (but not frustration) also predicted child performance on multiple EF tasks at age 3. Finally, 5-month infant and maternal affect indirectly predicted age 3 EF via age 2 language. Our results identify language as a mechanism through which children's early caregiving environment influences their EF development. Taken together, these findings illustrate the importance of applying a biopsychosocial perspective to the examination of early childhood EF development.

Expressive language in infancy and toddlerhood: The roles of child temperament and maternal parenting behaviors

Prompt, appropriate, and contingent maternal behaviors play a role in early language acquisition, as do individual differences in children's temperament. However, little work has investigated the combined influence of maternal psychosocial and child biological factors on expressive language development. The purpose of this study was to evaluate the concurrent and longitudinal contributions of responsive/intrusive parenting and child temperament to multiple expressive language outcomes at 10 and 24 months of age. Participants included 407 mothers and children (209 girls). Mothers completed questionnaires about their infant's temperament and language, and maternal parenting was coded during mother–child interaction tasks. Dependent variables included (1) gestures at 10 months, (2) vocabulary at 24 months, (3) mean length of utterance at 24 months, and (4) sentence complexity at 24 months. After controlling for child sex and maternal education, child temperament was associated with language outcomes at 10 and 24 months, whereas intrusive, but not responsive, parenting related to only 24 month language outcomes. Longitudinally, infant negative affectivity predicted sentence complexity in toddlerhood. These findings elucidate the presence of both psychological and biological predictors as they differentially influence various aspects of expressive language development across the first two postnatal years.

Vocabulary and Executive Functioning: A Scoping Review of the Unidirectional and Bidirectional Associations across Early Childhood

Early childhood marks a time where word learning is accompanied by rapid growth in the cognitive processes that underlie self-modulated and goal-directed behavior (i.e., executive functions). Although there is empirical evidence to support the association between executive functioning and vocabulary in childhood, inconsistent findings have been reported regarding the extent to which early executive functioning abilities predict later vocabulary outcomes and vice versa. To clarify the nature of the longitudinal relation between these two processes and to examine what, if any, claims can be made about their interdependence, a critical review of the literature was conducted. Also addressed are the conceptual and/or methodological differences that exist across studies conducted on this topic that may be contributing to some of the discrepancies reported in the longitudinal literature. Finally, this review provides practical and empirically informed future directions to serve as a resource for early childhood researchers advancing this area of study.

Context is key: Parasympathetic regulation in the classroom differentially predicts preschoolers' socially competent behaviors

Research shows that children's early social competence predicts their later academic and interpersonal success. Accordingly, early childhood education programs increasingly aim to evaluate and support children's social skill development. Despite ample theoretical and empirical work demonstrating the role of the parasympathetic nervous system (PNS) in supporting neurophysiological processes that underlie social behaviors, no study has explicitly tested whether the assessment of PNS activity in childhood educational settings provides insight into children's social functioning. The current study addresses this gap by examining the influence of context-specific PNS regulation, assessed via respiratory sinus arrhythmia (RSA), in predicting preschool children's socially competent behavior toward peers in the classroom. Results showed that: (1) RSA withdrawal (e.g., decreases relative to a baseline task) during unstructured classroom activities predicted children's socially competent behaviors during these unstructured activities but not during structured activities, whereas (2) withdrawal during structured classroom activities predicted children's socially competent behaviors during structured activities. These results indicate that PNS activity makes context-specific contributions to children's social behaviors and highlight the importance of assessing neurophysiological regulation in context.

Child maltreatment severity and sleep variability predict mother–infant RSA coregulation

Regulatory processes underlie mother-infant interactions and may be disrupted in adverse caregiving environments. Child maltreatment and sleep variability may reflect high-risk caregiving, but it is unknown whether they confer vulnerability for poorer mother–infant parasympathetic coordination. The aim of this study was to examine mother–infant coregulation of respiratory sinus arrhythmia (RSA) in relation to child maltreatment severity and night-to-night sleep variability in 47 low-income mother–infant dyads. Maternal and infant sleep was assessed with actigraphy and daily diaries for 7 nights followed by a mother–infant still-face procedure during which RSA was measured. Higher maltreatment severity was associated with weakened concordance in RSA coregulation related to the coupling of higher mother RSA with lower infant RSA, suggesting greater infant distress and lower maternal support. In addition, higher infant sleep variability was associated with infants’ lower mean RSA and concordance in lagged RSA coregulation such that lower maternal RSA predicted lower infant RSA across the still-face procedure, suggesting interrelated distress. The findings indicate that adverse caregiving environments differentially impact regulatory patterns in mother–infant dyads, which may inform modifiable health-risk behaviors as targets for future intervention.

Infant physiological activity and the early emergence of social communication

Early in life, social engagement is facilitated by effective regulation during times of rest and stress. Physiological regulation during social play and in response to sudden environmental changes or social stressors may play an important role in sustaining social engagement in infancy and facilitate the acquisition of early social-communication skills. The aim of this study was to investigate the role of physiological activity during social play, including respiratory sinus arrhythsmia (RSA) and heart rate-defined attention, in the early emergence of social-communication skills. Using RSA as an index of vagal tone, we measured vagal tone, vagal suppression, and heart rate-defined sustained attention during a social interaction with a caregiver (i.e., the Still-Face procedure) in 21 infants aged 3-4 months. At 9 months, caregivers reported on their infant's early social-communication skills. Results suggest that RSA, RSA suppression, and heart rate-defined sustained attention to a caregiver are significantly associated with early-emerging social-communication skills at 9 months. In addition, RSA and heart rate-defined sustained attention during social play were highly related. Suppression of RSA during the Still-Face phase of the infant-caregiver interaction emerged as a particularly strong predictor of later-developing social-communication skills, including 9-month-olds' ability to use eye gaze, facial expression, and gestures to communicate.

Characterizing change in vagal tone during the first three years of life: A systematic review and empirical examination across two longitudinal samples

Functioning of the parasympathetic nervous system (PNS), most often indexed by respiratory sinus arrhythmia (RSA), influences the volitional, cognitively-mediated forms of self-regulation across development. However, despite its clear relevance to children's self-regulation, and its utility as a transdiagnostic biomarker of emotion dysregulation and psychopathology, the ontogeny of vagal tone under conditions of homeostasis across infancy and early childhood is not well understood. The current research is comprised of two complementary studies. The first aims to address this gap by conducting a systematic review of the literature which has assessed resting RSA in the first three years of life. The second study uses data from two diverse, longitudinal datasets (n = 203 and n = 370) to model change in RSA from infancy to toddlerhood. Results from a systematic review of 62 studies meeting inclusion criteria suggest that measures of resting RSA increase over time and demonstrate moderate stability across infancy, toddlerhood, and preschool ages. Results from a series of models fit to longitudinal data in study two suggest that baseline RSA is characterized by stable increases across infancy and early childhood. Moreover, although there was equivocal evidence for individual variability in trajectories of RSA, the findings suggest that the individual differences in resting RSA may become entrenched in early life based on observed significant variance in growth model intercepts. In all, the current study contributes to our understanding of the developmental trajectories of baseline RSA across infancy and early childhood and should support future research examining links between children's parasympathetic regulation and their adjustment in early life.

Language and socioemotional development in early childhood: The role of conversational turns

This study examines the role of language environment (number of conversational turns) in the development of socioemotional competencies between 18 and 30 months. The language environment of 43 infants and their social-emotional competencies were measured at 18 months and again at 30 months. Multiple regressions showed a significant contribution of turns at 18 months on socioemotional competencies at 30 months, controlling for their initial levels, child vocalizations, maternal warmth, and social risk. Cross-lagged analysis revealed that the direction of the longitudinal relation between turns and emotional competencies is more likely to go from turns to socioemotional development than the other way around. Implications for theory and research are discussed.

Improving neurodevelopment in infants with complex congenital heart disease

Worldwide, more than 400,000 infants are born each year with complex congenital heart disease (CCHD) requiring surgical intervention within the first months of life. Although improvements in perioperative care have resulted in increased rates of survival, more than half of infants with CCHD have neurodevelopmental impairments affecting subsequent educational achievements, job opportunities, and mental health. Brain maturity and impaired outcomes in infants with CCHD are similar to those of prematurely born infants. Developmentally supportive care, including foundational application of kangaroo care (KC), improves neurodevelopment in premature infants. Provision of developmentally supportive care with KC during the early hospitalization of infants with CCHD has the potential to similarly improve neurodevelopment. The purposes of the article are to describe common congenital heart defects, describe developmentally supportive care with an emphasis on KC, and to offer specific recommendations for KC and research in infants with CCHD.

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.