Sympathetic-Parasympathetic Interaction and Externalizing Problems in Children with Autism Spectrum Disorder

Annual Research Review: What processes are dysregulated among emotionally dysregulated youth? - a systematic review

Proliferation of the term "emotion dysregulation" in child psychopathology parallels the growing interest in processes that influence negative emotional reactivity. While it commonly refers to a clinical phenotype where intense anger leads to behavioral dyscontrol, the term implies etiology because anything that is dysregulated requires an impaired regulatory mechanism. Many cognitive, affective, behavioral, neural, and social processes have been studied to improve understanding of emotion dysregulation. Nevertheless, the defective regulatory mechanism that might underlie it remains unclear. This systematic review of research on processes that affect emotion dysregulation endeavors to develop an integrative framework for the wide variety of factors investigated. It seeks to ascertain which, if any, constitutes an impaired regulatory mechanism. Based on this review, we propose a framework organizing emotion-relevant processes into categories pertaining to stimulus processing, response selection and control, emotion generation, closed- or open-loop feedback-based regulation, and experiential influences. Our review finds scant evidence for closed-loop (automatic) mechanisms to downregulate anger arousal rapidly. Open-loop (deliberate) regulatory strategies seem effective for low-to-moderate arousal. More extensive evidence supports roles for aspects of stimulus processing (sensory sensitivity, salience, appraisal, threat processing, and reward expectancy). Response control functions, such as inhibitory control, show robust associations with emotion dysregulation. Processes relating to emotion generation highlight aberrant features in autonomic, endocrine, reward functioning, and tonic mood states. A large literature on adverse childhood experiences and family interactions shows the unique and joint effects of interpersonal with child-level risks. We conclude that the defective closed-loop regulatory mechanisms that emotion dysregulation implies require further specification. Integrating research on emotion-relevant mechanisms along an axis from input factors through emotion generation to corrective feedback may promote research on (a) heterogeneity in pathogenesis, (b) interrelationships between these factors, and (c) the derivation of better-targeted treatments that address specific pathogenic processes of affected youth.

Autonomic Disequilibrium at Rest in Autistic Children and Adults

Autism Spectrum Disorder (ASD) symptoms have been proposed to be linked to Autonomic Nervous System (ANS) atypical functioning, in particular sympathetic hyper-arousal and parasympathetic under-activation. The objective of this study was to characterize autonomic functioning at rest in autistic and neurotypical children and adults. To characterize several aspects of autonomic functioning, we recorded simultaneously pupil diameter, heart rate and electrodermal activity during 5 min of rest in 44 children (6-12 years old, 22 autistic) and 42 adults (19-52 years old, 21 autistic). Several parameters allowed to characterize tonic and phasic indices of sympathetic and parasympathetic systems at rest. Autistic children exhibited the expected pattern of parasympathetic under-activation at rest compared to their typically developing (TD) peers, and with a tendency for a higher phasic sympathetic activity. Adults exhibited a reverse autonomic pattern, with autistic individuals showing higher sympathetic tonus and lower sympathetic phasic activity than their TD peers. In conclusion, we observed an autonomic disequilibrium at rest both in autistic children and adults, but with opposite patterns that could reflect adaptive compensation mechanisms during maturation. This disequilibrium in autistic children would switch from excessive phasic components to excessive tonic components in adults, possibly subtended by an atypical locus coeruleus functioning.

Differential Relations Between Parenting and Emotion Regulation in Children with ASD Across Dyadic and Independent Contexts

Many children with ASD exhibit difficulties with emotion regulation that greatly impair functioning. Certain intrinsic correlates of dysregulation have been identified in this population, but the search for potential environmental influences has been less fruitful. The current study examined several aspects of parenting as correlates of observed regulation in Autistic children, as measured in both parent-child and independent regulatory contexts. A diverse sample of 76 children with ASD aged 6 to 10 years participated in frustrating laboratory tasks with and without their primary caregivers, and the caregivers completed a parenting questionnaire. Emotion regulation, parental scaffolding, and gentle guidance were coded from videotaped interaction, and scores of parental involvement, positive parenting, and inconsistent discipline were obtained through parent report. Differential relations were observed between parenting and children's regulation when considered across contexts, with parental scaffolding associated with children's dyadic regulation and parents' reports of their involvement and discipline associated with children's independent regulation. Findings support previous evidence identifying a potential delay in the internalization of parental co-regulatory support in Autistic children, and highlight parental involvement as a previously unidentified unique correlate of independent regulation in this population. Implications for conceptualizations of emotion regulation in autism are discussed as is the importance of extending findings through further longitudinal research.

Piloting a battery to evaluate parasympathetic reactivity and externalizing behaviours during early childhood in autism spectrum disorder

Background

Respiratory Sinus Arrhythmia Reactivity (RSA-R) correlates both positively and negatively with externalizing behavior in autistic individuals. These inconsistencies may result from task-based differences. This pilot study measured RSA-R in 4-to 6-year-olds, across two time-points, using four validated tasks with matched baseline and challenge periods. Social, cognitive, sensory, and emotional tasks were employed to evaluate the use of a domain-specific approach in measuring RSA-R in young autistic children.

Methods

RSA and parent-reported externalizing behavior were collected from 16 children (Mage=5.60 years; 13 male; 12 white/caucasian; 15 non-hispanic/latine). RSA-R was measured by the difference score of the challenge task minus its corresponding comparison task. Correlations were computed to evaluate associations between RSA-R and behavior.

Results

RSA was reliably measured for 3/4 tasks (.694 ≤ ICCs ≤ .896). Only RSA-R during a social task correlated with externalizing behavior. These results support using a battery that measures a range of challenges, differing in social demands, to characterize how arousal contributes to emotion regulation demands among young autistic children.

Physiological Dysregulation in Children With and Without Externalizing Difficulties: Novel Insights From Intensive Longitudinal Data

Extant research on physiological dysregulation in children has focused on point-in-time measures and absolute mean levels of physiology. However, these methods do not capture dynamic fluctuations in physiology that characterize dysregulation. In the present work, we aimed to assess whether physiological dysregulation as captured by fluctuations rather than mean levels would differentiate between children with and without clinically elevated levels of externalizing behavior. As an exploratory approach, we examined fluctuations in children's physiological responses (i.e., root mean square of successive differences [RMSSD] in beat-to-beat heart rate intervals) to social transgression scenarios across 15 short-term measurement occasions (5-second bins). Controlling for mean RMSSD, as well as emotional and cognitive correlates of externalizing behavior (i.e., sympathy and inhibitory control), children with externalizing difficulties exhibited greater within-person fluctuations in RMSSD (i.e., physiological dysregulation) compared to children without externalizing difficulties. The present findings provide preliminary support for using intensive longitudinal data comprised of short-term physiological measurements and point to the centrality of within-child physiological variability as a marker of dysregulation, particularly amongst children with externalizing disorders for whom self-regulation is a core challenge.

ECG Recordings as Predictors of Very Early Autism Likelihood: A Machine Learning Approach

In recent years, there has been a rise in the prevalence of autism spectrum disorder (ASD). The diagnosis of ASD requires behavioral observation and standardized testing completed by highly trained experts. Early intervention for ASD can begin as early as 1-2 years of age, but ASD diagnoses are not typically made until ages 2-5 years, thus delaying the start of intervention. There is an urgent need for non-invasive biomarkers to detect ASD in infancy. While previous research using physiological recordings has focused on brain-based biomarkers of ASD, this study investigated the potential of electrocardiogram (ECG) recordings as an ASD biomarker in 3-6-month-old infants. We recorded the heart activity of infants at typical and elevated familial likelihood for ASD during naturalistic interactions with objects and caregivers. After obtaining the ECG signals, features such as heart rate variability (HRV) and sympathetic and parasympathetic activities were extracted. Then we evaluated the effectiveness of multiple machine learning classifiers for classifying ASD likelihood. Our findings support our hypothesis that infant ECG signals contain important information about ASD familial likelihood. Amongthe various machine learning algorithms tested, KNN performed best according to sensitivity (0.70 ± 0.117), F1-score (0.689 ± 0.124), precision (0.717 ± 0.128), accuracy (0.70 ± 0.117, p-value = 0.02), and ROC (0.686 ± 0.122, p-value = 0.06). These results suggest that ECG signals contain relevant information about the likelihood of an infant developing ASD. Future studies should consider the potential of information contained in ECG, and other indices of autonomic control, for the development of biomarkers of ASD in infancy.

Prefrontal Functional Connectivities in Autism Spectrum Disorders: A Connectopathic Disorder Affecting Movement, Interoception, and Cognition

The prefrontal cortex is included in a neuronal system that includes the basal ganglia, the thalamus, and the cerebellum. Most of the higher and more complex motor, cognitive, and emotional behavioral functions are thought to be found primarily in the frontal lobes. Insufficient connectivity between the medial prefrontal cortex (mPFC) and other regions of the brain that are distant from each other involved in top-down information processing rely on the global integration of data from multiple input sources and enhance low level perception processes (bottom-up information processing). The reduced deactivation in mPFC and in the rest of the Default Network during global task processing is consistent with the integrative modulatory role served by the mPFC. We stress the importance of understanding the degree to which sensory and movement anomalies in individuals with autism spectrum disorder (ASD) can contribute to social impairment. Further investigation on the neurobiological basis of sensory symptoms and its relationship to other clinical features found in ASD is required Treatment perhaps should not be first behaviorally based but rather based on facilitating sensory motor development.

Prevalence and Phenomenology of Anxiety in Preschool-Aged Children with Autism Spectrum Disorder

Individuals with autism spectrum disorder (ASD) are at a higher risk for developing co-occurring anxiety symptoms and diagnosable anxiety disorders compared to children with neurotypical development (NTD). The objective of the current study was to characterize the prevalence and phenomenology of anxiety in preschool-aged children with ASD. Our sample consisted of preschoolers (M = 52.8 months, SD = 10.8 months) with ASD (n = 77, 66% with co-occurring intellectual disability, ID) and NTD (n = 55). We employed multi-method (questionnaire and semi-structured diagnostic interview) and multi-informant (parent- and teacher-report) assessments of anxiety. Children with ASD were significantly more likely to meet criteria for an anxiety disorder than children with NTD. Over 70% of our sample with ASD met DSM-5 criteria for an anxiety disorder, with Specific Phobia and Separation Anxiety Disorder being the most prevalent. A range of specific fears was endorsed in the group with ASD, many of which overlapped with ASD symptoms. Parents, but not teachers, also reported greater anxiety symptoms for children with ASD relative to the comparison sample. Prevalence and phenomenology of anxiety in our sample with ASD generally did not differ between those with and without co-occurring ID, with the exception of higher rates of generalized anxiety in those without ID. Results showed poor concordance between parent questionnaires and a semi-structured diagnostic interview in detecting clinically-elevated anxiety in children with ASD. Implications for clinical practice and research are discussed.

Parasympathetic withdrawal indexes risk for emotion dysregulation in children with autism spectrum disorder

Children with autism spectrum disorder (ASD) experience significant difficulties with emotion regulation. Theory and empirical evidence suggest substantial biological contributions to regulatory challenges, which may be related to core ASD symptoms. Respiratory sinus arrythmia (RSA) is a measure of parasympathetic nervous system activity that serves as a putative biomarker for emotion regulation. Higher baseline RSA and more RSA reactivity (parasympathetic withdrawal; RSA-R) in response to challenge appear adaptive in non-clinical populations, but existing evidence for children with ASD remains inconclusive. The current study examined correlates of observed emotion dysregulation in 61 children with ASD between the ages of 6 and 10 years, including ASD symptom levels as well as both baseline RSA and concurrent RSA reactivity. Consistent with previous research, ASD symptom level was significantly correlated with observed dysregulation whereas additional factors such as child IQ were not. Baseline RSA was unrelated to observed dysregulation, but higher RSA reactivity predicted concurrent dysregulation above and beyond the contribution of child ASD symptoms. Findings contribute to an emerging understanding of dysregulation in these children, raise questions about the utility of traditional baseline RSA measures for this population, and clarify the functional significance of RSA reactivity as a risk factor for emotion dysregulation in children with ASD.

Parasympathetic functioning and sleep problems in children with autism spectrum disorder

Respiratory sinus arrhythmia (RSA), an index of parasympathetic nervous system activity, has been linked with sleep quality among children with neurotypical development. The current study extended examination of these processes to children with autism spectrum disorder (ASD), a group at considerable risk for sleep problems. Participants included 54 children with ASD (aged 6-10 years, 43% Hispanic). RSA data were collected via a wired MindWare system during a 3-min baseline and a 3-min challenge task. Parents reported on their children's sleep problems and sleep duration using the Children's Sleep Habits Questionnaire, Abbreviated. Although no significant correlations emerged between RSA indices and parent-reported child sleep, baseline RSA and RSA reactivity interacted in the prediction of sleep problems. For children with higher RSA reactivity, higher baseline RSA was associated with fewer sleep problems, but for children with lower RSA reactivity, baseline RSA was not predictive. No main effects or interactions of RSA predicted sleep duration. Findings suggest resilience against sleep problems for children with ASD presenting with higher baseline RSA and higher RSA reactivity. Implications of these results center upon directly targeting psychophysiology (i.e., parasympathetic nervous system regulation) as a possible mechanism to improve sleep in children with ASD, and developing personalized interventions based on physiological markers of risk and resilience.

Electrodermal Activity Moderates Sleep-Behavior Associations in Children with Autism Spectrum Disorder

Relative to children without autism spectrum disorder (ASD), children with ASD experience elevated sleep problems that can contribute to behavioral comorbidities. This study explored the interaction between psychophysiology and sleep to determine which children with ASD may be at risk for, or resilient to, effects of poor sleep on daytime behavior. Participants included 48 children (aged 6-10 years) with ASD. Measures of sympathetic nervous system activity (electrodermal activity; EDA) were collected during a baseline and in response to a laboratory challenge task. Parents reported on their children's sleep problems and behavioral functioning, including broad externalizing symptoms and situational noncompliance, using standardized questionnaires and a clinical interview. EDA moderated the significant positive associations between sleep problems and both behavioral outcomes. The link between sleep problems and broad externalizing symptoms and situational noncompliance was positive and significant in the context of lower baseline EDA and nonsignificant in the context of higher baseline EDA. Sleep problems also interacted with EDA reactivity in predicting situational noncompliance, but not broad externalizing symptoms. Findings highlight the complex interplay among sleep, daytime behavior, and psychophysiology in children with ASD. Results are interpreted in the context of differential susceptibility and dual-risk frameworks. This study underscores the importance of high-quality sleep for children with ASD, especially those with the biological sensitivity or vulnerability factors (i.e., EDA) identified in this study. Clinical implications are discussed, and directions for future research are provided.

Sleep Problems in Children with ASD and Gene Disrupting Mutations

Sleep difficulties are pervasive in autism spectrum disorder (ASD), yet how sleep problems relate to underlying biological mechanisms such as genetic etiology is unclear, despite recent reports of profound sleep problems in children with ASD-associated de novo likely gene disrupting (dnLGD) mutations, CHD8, DYRK1A, and ADNP. We aimed to inform etiological contributions to ASD and sleep by characterizing sleep problems in individuals with dnLGD mutations. Participants (N = 2886) were families who completed dichotomous questions about sleep problems within a medical history interview for their child with ASD (age 3-28 years). Confirmatory factor analyses compared between those with ASD and a dnLGD mutation and those with idiopathic ASD (i.e., no known genetic event, NON) highlighted four domains (sleep onset, breathing issues, nighttime awakenings, and daytime tiredness) with sleep onset as a strong factor for both groups. Overall, participant predictors indicated that internalizing behavioral problems and lower cognitive scores were related to increased sleep problems. Internalizing problems were also related to increase nighttime awakenings in the dnLGD group. As an exploratory aim, patterns of sleep issues are described for genetic subgroups with unique patterns including more overall sleep issues in ADNP (n = 19), problems falling asleep in CHD8 (n = 22), and increased daytime naps in DYRK1A (n = 23). Implications for considering genetically defined subgroups when approaching sleep problems in children with ASD are discussed.

The Gut-Brain-Microbiome Axis and Its Link to Autism: Emerging Insights and the Potential of Zebrafish Models

Research involving autism spectrum disorder (ASD) most frequently focuses on its key diagnostic criteria: restricted interests and repetitive behaviors, altered sensory perception, and communication impairments. These core criteria, however, are often accompanied by numerous comorbidities, many of which result in severe negative impacts on quality of life, including seizures, epilepsy, sleep disturbance, hypotonia, and GI distress. While ASD is a clinically heterogeneous disorder, gastrointestinal (GI) distress is among the most prevalent co-occurring symptom complex, manifesting in upward of 70% of all individuals with ASD. Consistent with this high prevalence, over a dozen family foundations that represent genetically distinct, molecularly defined forms of ASD have identified GI symptoms as an understudied area with significant negative impacts on quality of life for both individuals and their caregivers. Moreover, GI symptoms are also correlated with more pronounced irritability, social withdrawal, stereotypy, hyperactivity, and sleep disturbances, suggesting that they may exacerbate the defining behavioral symptoms of ASD. Despite these facts (and to the detriment of the community), GI distress remains largely unaddressed by ASD research and is frequently regarded as a symptomatic outcome rather than a potential contributory factor to the behavioral symptoms. Allowing for examination of both ASD's impact on the central nervous system (CNS) as well as its impact on the GI tract and the associated microbiome, the zebrafish has recently emerged as a powerful tool to study ASD. This is in no small part due to the advantages zebrafish present as a model system: their precocious development, their small transparent larval form, and their parallels with humans in genetics and physiology. While ASD research centered on the CNS has leveraged these advantages, there has been a critical lack of GI-centric ASD research in zebrafish models, making a holistic view of the gut-brain-microbiome axis incomplete. Similarly, high-throughput ASD drug screens have recently been developed but primarily focus on CNS and behavioral impacts while potential GI impacts have not been investigated. In this review, we aim to explore the great promise of the zebrafish model for elucidating the roles of the gut-brain-microbiome axis in ASD.

Parental Socialization of Emotion and Psychophysiological Arousal Patterns in Children with Autism Spectrum Disorder

Children with autism spectrum disorder (ASD) are at considerable risk for difficulties with emotion regulation and related functioning. Although it is commonly accepted that parents contribute to adaptive child regulation, as indexed by observable child behavior, theory and recent evidence suggest that parenting may also influence relevant underlying child physiological tendencies. The current study examined concurrent associations between two elements of parental socialization of emotion and measures of both sympathetic and parasympathetic nervous system activity in 61 children with ASD aged 6 to 10 years. To index parental socialization, parents reported on their reactions to their children's negative emotions, and parental scaffolding was coded from a dyadic problem-solving task. Children's baseline respiratory sinus arrhythmia (RSA), electrodermal reactivity (EDA-R), and RSA reactivity in response to challenge were obtained as measures of the children's physiological activity. Regression analyses indicated that supportive parent reactions were related to higher child baseline RSA, a biomarker of regulatory capacity. Fewer unsupportive parent reactions and higher quality scaffolding were associated with higher EDA-R, a physiological index of inhibition. The identification of these concurrent associations represents a first step in understanding the complex and likely bidirectional interplay between parent socialization and child physiological reactivity and regulation in this high-risk population.

Alterations in the autonomic nerve activities of prenatal autism model mice treated with valproic acid at different developmental stages

Autism spectrum disorder (ASD) is characterized by impairment of social communication, repetitive behavior and restrictive interest. The risk of ASD is strongly associated with the prenatal period; for instance, the administration of valproic acid (VPA) to pregnant mothers increases risk of ASD in the child. Patients with ASD often exhibit an alteration in the autonomic nervous system. In this study, we assessed the autonomic nervous activity at each prenatal developmental stage of model mice of ASD treated with VPA, to clarify the relationship between timing of exposure and ASD symptoms. The assessment of the autonomic nervous activity was performed based on the analysis of electrocardiography data collected from fetal and adult mice. Interestingly, VPA model mouse fetuses exhibited a significantly lower activity of the sympathetic nervous system. In contrast, sympathetic nervous activity at P0 was significantly higher. In adult VPA model mice, the parasympathetic activity of female VPA mice was suppressed. Moreover, female VPA mice showed reduced the parasympathetic activity after exposure to restraint stress. These results suggest that the autonomic nervous activity of VPA model mice was altered from the fetal stage, and that the assessment of autonomic nervous activities at an early developmental stage could be useful for the understanding of ASD.

Atypical Emotional Electrodermal Activity in Toddlers with Autism Spectrum Disorder

Past studies in autism spectrum disorder (ASD) indicate atypical peripheral physiological arousal. However, the conditions under which these atypicalities arise and their link with behavioral emotional expressions and core ASD symptoms remain uncertain. Given the importance of physiological arousal in affective, learning, and cognitive processes, the current study examined changes in skin conductance level (ΔSCL) in 41 toddlers with ASD (mean age: 22.7 months, SD: 2.9) and 32 age-matched toddlers with typical development (TD) (mean age: 21.6 months, SD: 3.6) in response to probes designed to induce anger, joy, and fear emotions. The magnitude of ΔSCL was comparable during anger (P = 0.206, d = 0.30) and joy (P = 0.996, d = 0.01) conditions, but significantly lower during the fear condition (P = 0.001, d = 0.83) in toddlers with ASD compared to TD peers. In the combined samples, ΔSCL positively correlated with intensity of behavioral emotional expressivity during the anger (r[71] = 0.36, P = 0.002) and fear (r[68] = 0.32, P = 0.007) conditions, but not in the joy (r[69] = -0.15, P = 0.226) condition. Finally, ΔSCL did not associate with autism symptom severity in any emotion-eliciting condition in the ASD group. Toddlers with ASD displayed attenuated ΔSCL to situations aimed at eliciting fear, which may forecast the emergence of highly prevalent internalizing and externalizing problems in this population. The study putatively identifies ΔSCL as a dimension not associated with severity of autism but with behavioral responses in negatively emotionally challenging events and provides support for the feasibility, validity, and incipient utility of examining ΔSCL in response to emotional challenges in very young children. LAY SUMMARY: Physiological arousal was measured in toddlers with autism exposed to frustrating, pleasant, and threatening tasks. Compared to typically developing peers, toddlers with autism showed comparable arousal responses to frustrating and pleasant events, but lower responses to threatening events. Importantly, physiological arousal and behavioral expressions were aligned during frustrating and threatening events, inviting exploration of physiological arousal to measure responses to emotional challenges. Furthermore, this study advances the understanding of precursors to emotional and behavioral problems common in older children with autism. Autism Res 2020, 13: 1476-1488. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.