Autonomic response in autism spectrum disorder: Relationship to social and cognitive functioning

Toward effective oxytocin interventions in autism: Overcoming challenges and harnessing opportunities

Intranasal administration of oxytocin is emerging as a potential pharmacological option for mitigating social difficulties and regulating stress in autism spectrum disorder. However, initial single-dose and multiple-dose trials showed mixed results, with some demonstrating improvements in social and repetitive behavior and others showing no benefit over placebo. This perspective aims to elucidate factors contributing to this variability and to highlight pitfalls and opportunities in the field. We identified two major factors: design-related elements and individual participant characteristics. Pertaining to design-related elements, optimal dosing regimens have yet to be established, but appear to favor moderate intervention durations (i.e., 4-6 weeks) with intermittent and intermediate dosing (i.e., 24-32 IU every other day). Also, the context of the intervention seems crucial, as enhanced outcomes are mainly observed when oxytocin administration is paired with a socially stimulating and supporting environment. In addition, more adequate outcome measures have to be established to effectively assess oxytocin's impact, including behavioral scales and objective biophysiological markers tapping into stress and neurophysiological regulation. Future research should also account for individual participant differences in biological sex, developmental stage and cognitive and adaptive functioning, and incorporate (epi)genetic screening to identify responders. Overall, refining study designs and personalizing intervention protocols are essential for optimizing oxytocin's prosocial and anxiolytic effect in autism.

Toward better outcome measurement for insomnia in children with autism spectrum disorder

LAY ABSTRACT

Insomnia, trouble falling asleep or staying asleep, is common in autistic children. In a previous report, we described the results of focus groups with parents of autistic children toward the development of the Pediatric Autism Insomnia Rating Scale. In this article, we report on the steps taken to complete the Pediatric Autism Insomnia Rating Scale. With help from the Simons Foundation registry, we collected information from parents on 1185 children with autism spectrum disorder to test the new measure. These results were evaluated using standard statistical methods such as factor analysis. To confirm the validity of the new measure, we enrolled a separate sample of 134 autistic children for a detailed assessment by video conference. This step showed that the Pediatric Autism Insomnia Rating Scale is clearly measuring symptoms of insomnia in children with autism spectrum disorder and not related problems such as hyperactivity, repetitive behavior, or anxiety. We also showed that the total score on the Pediatric Autism Insomnia Rating Scale is stable when repeated over a brief period of time. This is important because a measure that is not stable over a brief period of time would not be suitable as an outcome measure. In summary, the Pediatric Autism Insomnia Rating Scale is a brief and valid measure of insomnia in children with autism spectrum disorder that provides reliable scores.

Pupillary response during social emotion tasks in autism spectrum disorder

Autistic individuals encounter challenges in recognizing emotional expressions of others. Pupillary response has been proposed as an indicator of arousal dysregulation or cognitive load. The pupillary response of autistic individuals during socio-affective tasks remains unclear. This study investigated pupillary response in autistic adults when viewing emotional faces/eyes and recognizing emotions during the Reading the Mind in the Eyes Test (RMET) and watching interpersonal touch scenes in the social touch task. The study included 98 participants diagnosed with autism spectrum disorder and 37 typically developing controls (TD). Pupil size was measured using the Tobii X2-30 Eye Tracker. The results showed that autistic adults had larger maximal pupil sizes, smaller minimal pupil sizes, and greater change rates of pupil size, particularly during the RMET Eyes task. Clinical correlations revealed that attention switching difficulty positively correlated with mean pupil size in TD participants, while social communication deficits positively correlated with mean pupil size in autistic participants. In conclusion, our findings suggest atypical pupillary responses in autistic adults during socio-affective tasks, indicating heightened cognitive demand. Further investigation is necessary to understand the underlying mechanisms and their association with autistic traits.

The Physiological and Clinical-Behavioral Effects of Heart Rate Variability Biofeedback in Adolescents with Autism: A Pilot Randomized Controlled Trial

Adolescents with autism present lower levels of cardiac vagal modulation. It was hypothesized that Heart Rate Variability Biofeedback (HRVB) increases cardiac vagal modulation in adolescents with autism, resulting in positive effects on physiological and psychosocial parameters. It was also hypothesized that home-based HRVB training is feasible. In a single-blind, randomized sham-controlled pilot trial, adolescents with autism performed supervised HRVB (n = 24) or sham training (n = 20). Subsequently, half of the adolescents received HRVB training at home, whereas the other subset did not practice. Physiological, cortisol and behavioral data were collected during stress-provoking assessments before and after each training period. Supervised HRVB resulted in a late increase in cardiac vagal modulation in adolescents with autism. Heart rate increased and cortisol decreased significantly immediately after supervised HRVB, but none of these effects remained after follow-up. Following supervised HRVB, no significant change in psychosocial functioning was found. Home-based HRVB was feasible, adolescents reported lower symptoms of stress, but a significant decrease in compliance rate was found. HRVB is feasible and effective in adolescents with autism given the late-emerging increases in cardiac vagal modulation and decrease in stress symptoms. Replicating this study with a larger sample and further exploration of the working mechanisms of HRVB are recommended. ClinicalTrials.gov , NCT04628715.

Intact gesture cueing of attention but attenuated sensitivity to peripheral social targets in autistic children: An eye-tracking and pupillometric study

BACKGROUND

Altered automatic attention cueing has been reported in autistic children. Yet less is known about how autistic children would respond when the social cue that directs attention occurs in an implied social interaction.

METHODS

By using eye-tracking, the current study examined orienting responses to a socially-relevant target or a nonsocial target cued by a goal-directed social gesture in autistic children. Saccadic reaction time and pupillary responses were employed to measure gaze behavior and physiological arousal of autistic children.

RESULTS

Both groups of children showed reflexive orienting to the target regardless of its sociality, whereas typically developing (TD) children exhibited faster gaze shift than autistic children when the target was a social stimulus. An increased pupil dilation was observed in autistic children in response to stimuli relative to TD children. Further, autistic children showed larger baseline pupil response.

CONCLUSIONS

Autistic children show attenuated sensitivity to social targets and atypical pupil responses, which may be due to the dysfunction of locus coeruleus (LC) - norepinephrine (NE) system.

Metabolic network analysis of pre-ASD newborns and 5-year-old children with autism spectrum disorder

Classical metabolomic and new metabolic network methods were used to study the developmental features of autism spectrum disorder (ASD) in newborns (n = 205) and 5-year-old children (n = 53). Eighty percent of the metabolic impact in ASD was caused by 14 shared biochemical pathways that led to decreased anti-inflammatory and antioxidant defenses, and to increased physiologic stress molecules like lactate, glycerol, cholesterol, and ceramides. CIRCOS plots and a new metabolic network parameter,V ° net, revealed differences in both the kind and degree of network connectivity. Of 50 biochemical pathways and 450 polar and lipid metabolites examined, the developmental regulation of the purine network was most changed. Purine network hub analysis revealed a 17-fold reversal in typically developing children. This purine network reversal did not occur in ASD. These results revealed previously unknown metabolic phenotypes, identified new developmental states of the metabolic correlation network, and underscored the role of mitochondrial functional changes, purine metabolism, and purinergic signaling in autism spectrum disorder.

The relationship between subjective difficulty in interoceptive processing and accuracy of heartbeat perception in autistic individuals

Most autistic people experience difficulties in sensory processing, including interoceptive processing. For example, they often report subjective difficulties in the interoceptive processing of interoceptive input, such as difficulty in interpreting bodily signals, including hunger, thirst, and fatigue. However, whether these subjective interoceptive difficulties are from underlying problems in interoceptive accuracy remains unclear. This study investigated the relationship between subjective interoceptive difficulty and behavioral interoceptive accuracy in autistic adults and a control group. Subjective interoceptive accuracy was measured using an interoceptive sensitivity questionnaire, and behavioral interoceptive accuracy was measured using a heartbeat counting task. The results showed no significant relationship between subjective interoceptive difficulty and behavioral interoceptive accuracy in the autistic or control groups. This suggests that subjective interoceptive difficulty and behavioral interoceptive accuracy reflect different aspects of interoceptive processing. One possible interpretation is that autistic adults can identify individual local sensory inputs, such as heartbeats, however, they have difficulty integrating multiple inputs and recognizing internal body states such as hunger and fatigue.

C. Social Context in Stress and Autism: Comparing Physiological Profiles Across Two Social Paradigms in Youth with and without Autism Spectrum Disorder

Background

The social world is often stressful for individuals with autism spectrum disorder (ASD). Research shows youth with ASD demonstrate physiological hyperreactivity to some social stressors (e.g., interaction) but not others (e.g., evaluation); therefore, this study examined diagnosis (ASD or typical development (TD)), social context, perceived anxiety, and physiological responsivity across multiple stress systems; namely, the hypothalamic pituitary adrenal (HPA) axis and autonomic nervous system (ANS).

Method

This study examined 244 ten-to-thirteen-year-olds with ASD (N = 140) or TD (N = 104). Physiological responses, measured by salivary cortisol, heart rate (HR), and respiratory sinus arrhythmia (RSA), were assessed before and after a social evaluative threat paradigm (Trier Social Stress Test; TSST) and social interaction (Trier Social Stress Test- Friendly; TSST-F). Mediation models examined the relationships between anxiety, diagnosis, and physiology.

Results

Significant three-way interactions were observed for cortisol (p=0.007) and HR (p=0.002), suggesting diagnostic groups respond differently across context and time points. There was no significant interaction for RSA (p=0.149), although ASD youth had significantly lower RSA overall (p=0.038). State and trait anxiety did not mediate the relationship between diagnosis and physiology (all p>0.05).

Conclusions

Findings emphasize the critical role of context and a multisystem approach in examination of physiological social stress in youth with ASD. Results provide a foundation to elucidate unique response patterns across physiological systems to more precisely identify those with heightened physiological arousal across social contexts. It is proposed that future identification of subtypes may ultimately inform approaches for enhancing social engagement.

Autonomic nervous system responses to social stimuli among autistic individuals: A systematic review and meta-analysis

Physiological responses to environmental and social stimuli have been studied broadly in relation to psychological states and processes. This may be especially important regarding autistic individuals, who show disparities in social interactions. However, findings from studies assessing autonomic nervous system (ANS) responses of autistic individuals present contradictions, with reports showing both autonomic disparities and intact autonomic functioning. The current study aimed to review the existing literature and to estimate if there is a difference between autistic individuals and neurotypical (NT) individuals in their autonomic responses to social stimuli. Furthermore, the study examined factors that may moderate this difference, including the type of physiological function measured, the level of participation required, as well as the age and intellectual functioning of the participants. The meta-analysis revealed a small and statistically insignificant overall difference between autistic and NT individuals, albeit with high heterogeneity. A further nested moderator analysis revealed a significant difference between autistic and NT individuals in physiological response that reflects mainly a parasympathetic nervous system (PNS) activity. Another difference was found in physiological response that reflects a combined activity of the sympathetic and parasympathetic systems, but only for experimental tasks that demanded active participation in social interactions. These results suggest a distinctiveness in autonomic regulation of autistic individuals in social situations, and point to the PNS as an important study objective for future investigation.

Coactivation of Autonomic and Central Nervous Systems During Processing of Socially Relevant Information in Autism Spectrum Disorder: A Systematic Review

Body-brain interaction provides a novel approach to understand neurodevelopmental conditions such as autism spectrum disorder (ASD). In this systematic review, we analyse the empirical evidence regarding coexisting differences in autonomic (ANS) and central nervous system (CNS) responses to social stimuli between individuals with ASD and typically developing individuals. Moreover, we review evidence of deviations in body-brain interaction during processing of socially relevant information in ASD. We conducted systematic literature searches in PubMed, Medline, PsychInfo, PsychArticles, and Cinahl databases (until 12.1.2022). Studies were included if individuals with ASD were compared with typically developing individuals, study design included processing of social information, and ANS and CNS activity were measured simultaneously. Out of 1892 studies identified based on the titles and abstracts, only six fulfilled the eligibility criteria to be included in synthesis. The quality of these studies was assessed using a quality assessment checklist. The results indicated that individuals with ASD demonstrate atypicalities in ANS and CNS signalling which, however, are context dependent. There were also indications for altered contribution of ANS-CNS interaction in processing of social information in ASD. However, the findings must be considered in the context of several limitations, such as small sample sizes and high variability in (neuro)physiological measures. Indeed, the methodological choices varied considerably, calling for a need for unified guidelines to improve the interpretability of results. We summarize the current experimentally supported understanding of the role of socially relevant body-brain interaction in ASD. Furthermore, we propose developments for future studies to improve incremental knowledge building across studies of ANS-CNS interaction involving individuals with ASD.

Assessment of autonomic symptom scales in patients with neurodevelopmental diagnoses using electronic health record data

Background

Sleep disturbances, gastrointestinal problems, and atypical heart rate are commonly observed in patients with autism spectrum disorder (ASD) and may relate to underlying function of the autonomic nervous system (ANS). The overall objective of the current study was to quantitatively characterize features of ANS function using symptom scales and available electronic health record (EHR) data in a clinically and genetically characterized pediatric cohort.

Methods

We assessed features of ANS function via chart review of patient records adapted from items drawn from a clinical research questionnaire of autonomic symptoms. This procedure coded for the presence and/or absence of targeted symptoms and was completed in 3 groups of patients, including patients with a clinical neurodevelopmental diagnosis and identified genetic etiology (NPD, n=244), those with an ASD diagnosis with no known genetic cause (ASD, n=159), and age and sex matched controls (MC, n=213). Symptoms were assessed across four main categories: (1) Mood, Behavior, and Emotion; (2) Secretomotor, Sensory Integration; (3) Urinary, Gastrointestinal, and Digestion; and (4) Circulation, Thermoregulation, Circadian function, and Sleep/Wake cycles.

Results

Chart review scores indicate an increased rate of autonomic symptoms across all four sections in our NPD group as compared to scores with ASD and/or MC. Additionally, we note several significant relationships between individual differences in autonomic symptoms and quantitative ASD traits.

Conclusion

These results highlight EHR review as a potentially useful method for quantifying variance in symptoms adapted from a questionnaire or survey. Further, using this method indicates that autonomic features are more prevalent in children with genetic disorders conferring risk for ASD and other neurodevelopmental diagnoses.

Probiotic and intra-nasal oxytocin combination therapy on autonomic function and gut-brain axis signaling in young children and teens with autism spectrum disorder

Autonomic dysfunction has been widely studied in individuals with autism spectral disorder (ASD); however, the autonomic response to probiotic and oxytocin (OT) combination intervention has not yet been explored. We conducted the present study that includes 35 individuals with ASD aged 3-20 years to explore autonomic responses to daily Lactobacillus plantarum probiotic supplementation and OT nasal spray treatment both alone and in combination. We identified significant improvements in autonomic indices from subjects receiving combination treatment relative to those receiving placebo. Parameters that were observed to improve following combination treatment are time domain metrics of heart rate variability (HRV), including the root mean square of successive differences between normal heartbeats (RMSSD), standard deviation of normal-to-normal R-R intervals (SDNN), and proportion of the number of pairs of adjacent NN intervals that differ by more than 50ms (pNN50, p < 0.05). Furthermore, individuals that received either probiotics or OT alone demonstrated fewer changes in RMSSD, pNN50, and SDNN. Several parameters that demonstrated significant improvements in combination therapy were found to be correlated with baseline levels of OT (LF power: r = -0.86, p = 0.024; mean HR: r = 0.89, p = 0.012). Additionally, Social Responsiveness Scale (SRS) raw total scores (mean HR, r = 0.86, p = 0.024) and Aberrant Behavior Checklist (ABC) raw total scores (mean HR r = 0.94, p = 0.017) were correlated with mean heart rate (HR) and HRV-derived parameters. These results provide further evidence of synergy of probiotic and OT combination and help us gain a better understanding of the role of the gut-brain axis in ASD phenotypes and pathogenesis.

Development and Parasympathetic Regulation in Male and Female Adolescents with Autism Spectrum Disorder: A Two-Timepoint Longitudinal Study

Prolonged dysregulation of the autonomic nervous system (ANS) may increase propensity for physical or psychiatric illness. The current study examined differences in respiratory sinus arrhythmia (RSA) regulation in 215 adolescents with or without autism spectrum disorder (ASD) at Time 1 (T1; 10-13 years old) and 1 year later (Time 2; T2). Linear mixed effects models demonstrated lower RSA regulation in ASD, and a small interaction effect, showing blunted change in RSA from T1 to T2. Developmental differences in RSA regulation were particularly notable in females with ASD and those taking psychotropic medications. Results expand previous findings of reduced parasympathetic regulation in ASD by revealing a blunted developmental slope, indicating diagnostic differences may persist or worsen over time, particularly in females.

Heart Rate Variability Code: Does It Exist and Can We Hack It?

A code is generally defined as a system of signals or symbols for communication. Experimental evidence is synthesized for the presence and utility of such communication in heart rate variability (HRV) with particular attention to fetal HRV: HRV contains signatures of information flow between the organs and of response to physiological or pathophysiological stimuli as signatures of states (or syndromes). HRV exhibits features of time structure, phase space structure, specificity with respect to (organ) target and pathophysiological syndromes, and universality with respect to species independence. Together, these features form a spatiotemporal structure, a phase space, that can be conceived of as a manifold of a yet-to-be-fully understood dynamic complexity. The objective of this article is to synthesize physiological evidence supporting the existence of HRV code: hereby, the process-specific subsets of HRV measures indirectly map the phase space traversal reflecting the specific information contained in the code required for the body to regulate the physiological responses to those processes. The following physiological examples of HRV code are reviewed, which are reflected in specific changes to HRV properties across the signal-analytical domains and across physiological states and conditions: the fetal systemic inflammatory response, organ-specific inflammatory responses (brain and gut), chronic hypoxia and intrinsic (heart) HRV (iHRV), allostatic load (physiological stress due to surgery), and vagotomy (bilateral cervical denervation). Future studies are proposed to test these observations in more depth, and the author refers the interested reader to the referenced publications for a detailed study of the HRV measures involved. While being exemplified mostly in the studies of fetal HRV, the presented framework promises more specific fetal, postnatal, and adult HRV biomarkers of health and disease, which can be obtained non-invasively and continuously.

Social and executive functioning in individuals with autism spectrum disorder without intellectual disability: The case-control study protocol of the CNeSA study

Several studies suggest that children and adolescents with autism spectrum disorder (ASD) often present deficits in executive functions (EFs). The research on cold EF shows a high heterogeneity across different cohorts of patients as well as different study designs, while studies investigating hot EF and their relationship with different ASD phenotypes are still limited and related only to specific domains, although this concept could contribute to clarify the phenotypical variability by explaining the difficulties encountered by individuals with ASD in daily life, where stimuli are often emotionally charged. With the aim to identify specific neuropsychological profiles in children and adolescents with ASD without intellectual disability, we designed a study protocol comparing a clinical sample of individuals with ASD to aged-matched (10-17 years) typically developing controls (TDC) on a neuropsychological test battery investigating both "cold" and "hot" EF with the purpose of further investigating their relationships with ASD symptoms. Autonomic measures including heart rate, heart rate variability, skin conductance, and salivary cortisol were also recorded before/during/after the neuropsychological testing session. This paper describes the case-control study protocol named "Caratterizzazione NEuropsicologica del disturbo dello Spettro Autistico, senza Disabilità Intellettiva, CNeSA study," its rationale, the specific outcome measures, and their implications for the clinical management of individuals with ASD and a precision medicine approach.

Cardiac autonomic control in Rett syndrome: Insights from heart rate variability analysis

Rett syndrome (RTT) is a rare and severe neurological disorder mainly affecting females, usually linked to methyl-CpG-binding protein 2 (MECP2) gene mutations. Manifestations of RTT typically include loss of purposeful hand skills, gait and motor abnormalities, loss of spoken language, stereotypic hand movements, epilepsy, and autonomic dysfunction. Patients with RTT have a higher incidence of sudden death than the general population. Literature data indicate an uncoupling between measures of breathing and heart rate control that could offer insight into the mechanisms that lead to greater vulnerability to sudden death. Understanding the neural mechanisms of autonomic dysfunction and its correlation with sudden death is essential for patient care. Experimental evidence for increased sympathetic or reduced vagal modulation to the heart has spurred efforts to develop quantitative markers of cardiac autonomic profile. Heart rate variability (HRV) has emerged as a valuable non-invasive test to estimate the modulation of sympathetic and parasympathetic branches of the autonomic nervous system (ANS) to the heart. This review aims to provide an overview of the current knowledge on autonomic dysfunction and, in particular, to assess whether HRV parameters can help unravel patterns of cardiac autonomic dysregulation in patients with RTT. Literature data show reduced global HRV (total spectral power and R-R mean) and a shifted sympatho-vagal balance toward sympathetic predominance and vagal withdrawal in patients with RTT compared to controls. In addition, correlations between HRV and genotype and phenotype features or neurochemical changes were investigated. The data reported in this review suggest an important impairment in sympatho-vagal balance, supporting possible future research scenarios, targeting ANS.

Identifying phenotypic and physiological subgroups of preschoolers with autism spectrum disorder

BACKGROUND

To understand the emergence of symptoms in autism spectrum disorder (ASD), we need to identify the mechanisms that underpin the development of core social skills. Mounting evidence indicates that young children with later ASD attend less to other people, which could compromise learning opportunities with cascading effects. Passive looking behaviour does not tell us about engagement with visual information, but measures of physiological arousal can provide information on the depth of engagement. In the current study, we use heart rate (HR) and heart rate variability (HRV) to measure engagement with social dynamic stimuli in ASD.

METHODS

Sixty-seven preschoolers with ASD and 65 typical developing preschoolers between 2 and 4 years of age participated in a study where HR was measured during viewing of social and non-social videos. Using latent profile analyses, more homogeneous subgroups of children were created based on phenotype and physiology.

RESULTS

Preschool-aged children with ASD, regardless of their non-verbal, verbal and social competencies, do not differ in overall HR or HRV compared to TD children. However, the ASD group showed a larger increase in HR (more disengagement) than the TD group to later-presented social stimuli. Phenotypic and physiological profiles showed this was primarily the case for children with below average verbal and non-verbal skills, but not necessarily those with more ASD symptoms.

CONCLUSION

Children with ASD, especially a subgroup showing moderate cognitive delays, show an increase in HR to social stimuli over time; this may reflect difficulties re-engaging with social information when attention is waning.

Atypical Response to Affective Touch in Children with Autism: Multi-Parametric Exploration of the Autonomic System

This study aimed at evaluating the autonomic response to pleasant affective touch in children with Autism Spectrum Disorders (ASD) and age-matched typically developing (TD) peers, thanks to multiple autonomic nervous system (ANS) parameters and by contrasting CT (C-tactile fibers) high- vs. low-density territory stimulations. We measured pupil diameter, skin conductance, and heart rate during gentle stroking of two skin territories (CT high- and low-density, respectively, forearm and palm of the hand) in thirty 6-12-year-old TD children and twenty ASD children. TD children showed an increase in pupil diameter and skin conductance associated with a heart rate deceleration in response to tactile stimulations at the two locations. Only the pupil was influenced by the stimulated location, with a later dilation peak following CT low-density territory stimulation. Globally, ASD children exhibited reduced autonomic responses, as well as different ANS baseline values compared to TD children. These atypical ANS responses to pleasant touch in ASD children were not specific to CT-fiber stimulation. Overall, these results point towards both basal autonomic dysregulation and lower tactile autonomic evoked responses in ASD, possibly reflecting lower arousal and related to social disengagement.

Higher scores on autonomic symptom scales in pediatric patients with neurodevelopmental disorders of known genetic etiology

INTRODUCTION

Features of underlying autonomic dysfunction, including sleep disturbances, gastrointestinal problems, and atypical heart rate, have been reported in neurodevelopmental conditions, including autism spectrum disorder (ASD). The current cross-sectional, between-groups study aimed to quantify symptoms of autonomic dysfunction in a neurodevelopmental pediatric cohort characterized by clinical diagnoses as well as genetic etiology.

METHOD

The Pediatric Autonomic Symptom Scales (PASS) questionnaire was used to assess autonomic features across a group of patients with clinical neurodevelopmental diagnoses (NPD; N = 90) and genetic etiologies. Patients were subdivided based on either having a clinical ASD diagnosis (NPD-ASD; n = 37) or other non-ASD neurodevelopmental diagnoses, such as intellectual disability without ASD, speech and language disorders, and/or attention deficit hyperactivity disorder (NPD-OTHER; n = 53). Analyses focused on characterizing differences between the NPD group compared to previously published reference samples, as well as differences between the two NPD subgroups (NPD-ASD and NPD-OTHER).

RESULTS

Our results indicate higher PASS scores in our NPD cohort relative to children with and without ASD from a previously published cohort. However, we did not identify significant group differences between our NPD-ASD and NPD-OTHER subgroups. Furthermore, we find a significant relationship between quantitative ASD traits and symptoms of autonomic function.

CONCLUSION

This work demonstrates the utility of capturing quantitative estimates of autonomic trait dimensions that may be significantly linked with psychosocial impairments and other core clinical features of ASD.

Measurement of interpersonal physiological synchrony in dyads: A review of timing parameters used in the literature

When individuals share interpersonal connections, such as the bond between a mother and child or between a therapist and their client, they often exhibit measurable coordination of some physiological response patterns during their interactions known as interpersonal physiological synchrony (IPS Butler, 2011; Palumbo et al., 2016; Tscacher & Meier, 2019). However, as there is no single definition of IPS in the literature, researchers across fields have not established a standardized method for its study. This paper outlines methodological considerations that researchers should take into account when designing studies of IPS. Due to the inherent temporal component of synchrony analyses, we direct particular focus to the issue of measurement timing. Synchrony is described across multiple physiological processes, including electrodermal skin activation, cardiac function, respiration, and neural oscillatory activity, and we make specific recommendations for each. Across physiological measures and analytic strategies, we recommend that when determining an experimental timeframe in which to isolate periods of dyadic IPS, researchers should account for the timing of both the biological systems of interest and the psychological processes theorized to underlie their activity in that particular context. In adopting this strategy, researchers can ensure that they capture all of the fluctuations associated with a psychological process of interest and can add to the growing body of literature examining physiological correlates of interpersonal bonds.

The autism-associated Meis2 gene is necessary for cardiac baroreflex regulation in mice

Recent understanding of Autism Spectrum Disorder (ASD) showed that peripheral primary mechanosensitive neurons involved in touch sensation and central neurons affected in ASD share transcriptional regulators. Mutant mice for ASD-associated transcription factors exhibit impaired primary tactile perception and restoring those genes specifically in primary sensory neurons rescues some of the anxiety-like behavior and social interaction defects. Interestingly, peripheral mechanosensitive sensory neurons also project to internal organs including the cardiovascular system, and an imbalance of the cardio-vascular sympathovagal regulation is evidenced in ASD and intellectual disability. ASD patients have decreased vagal tone, suggesting dysfunction of sensory neurons involved in cardio-vascular sensing. In light of our previous finding that the ASD-associated Meis2 gene is necessary for normal touch neuron development and function, we investigated here if its inactivation in mouse peripheral sensory neurons also affects cardio-vascular sympathovagal regulation and baroreflex. Combining echocardiography, pharmacological challenge, blood pressure monitoring, and heart rate variability analysis, we found that Meis2 mutant mice exhibited a blunted vagal response independently of any apparent cardiac malformation. These results suggest that defects in primary sensory neurons with mechanosensitive identity could participate in the imbalanced cardio-vascular sympathovagal tone found in ASD patients, reinforcing current hypotheses on the role of primary sensory neurons in the etiology of ASD.

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.

Diagnostic and Physical Effects in Parasympathetic Response to Social Evaluation in Youth With and Without Autism Spectrum Disorder

Individuals with autism spectrum disorder (ASD) may demonstrate atypical autonomic (ANS) responses; however, research remains inconsistent. This study examined parasympathetic response during social evaluation in 241 youth (10-13 years) with ASD (n = 138) or typical development (TD; n = 103). Diagnosis, age, pubertal development, and body mass index (BMI) were hypothesized to be associated with ANS function. Linear mixed effects models demonstrated lower RSA in ASD relative to TD in a base model with no covariates. However, when accounting for differences in BMI, there was no evidence of atypical parasympathetic regulation in youth with ASD. As lower parasympathetic regulation may increase susceptibility for a number of conditions, it will be important to elucidate the link between BMI and the ANS, especially in ASD.

An Observational Study of Heart Rate Variability Using Wearable Sensors Provides a Target for Therapeutic Monitoring of Autonomic Dysregulation in Patients with Rett Syndrome

Rett Syndrome (RTT) is a complex neurodevelopmental disorder that has multi-system involvement with co-occurring epilepsy, breathing problems and autonomic dysregulation. Autonomic dysregulation can increase the risk of cardiorespiratory vulnerability in this patient group. Assessment of heart rate variability (HRV) provides an overview of autonomic health in RTT and offers insight into how the sympathetic and parasympathetic components of the nervous system function. However, to our knowledge, no study has evaluated HRV in Rett patients to assess how the dynamics of autonomic function vary with age and changes during the day and/or night. Using non-invasive wearable sensors, we measured HRV in 45 patients with RTT and examined the time and frequency domain sympathetic and parasympathetic indices. Among the HRV indices assessed, heart rate decreases with age and is lower in the night across all ages studied. The sympathetic index (SDNN) and the parasympathetic indices (RMSSD and pNN50) are not seen to change with age. Nevertheless, these indices were all higher during the day when compared to the night. Our findings appear to show that Rett patients are less adaptable to autonomic changes during the night. In the clinical setting, this might be more relevant for patients with severe psychopathology.

Indices of Heart Rate Variability and Performance During a Response-Conflict Task Are Differently Associated With ADHD and Autism

We investigated autonomic arousal, attention and response conflict, in ADHD and autism. Heart rate variability (HRV), and behavioral/electrophysiological indices of performance, were recorded during a task with low and high levels of response conflict in 78 children/adolescents (7-15 years old) with ADHD, autism, comorbid ADHD+autism, or neurotypical. ANOVA models were used to investigate effects of ADHD and autism, while a mediation model was tested to clarify the relationship between ADHD and slower performance. Slower and less accurate performance characterized ADHD and autism; however, atypical electrophysiological indices differently characterized these conditions. The relationship between ADHD and slower task performance was mediated by reduced HRV in response to the cue stimulus. Autonomic hypo-arousal and difficulties in mobilizing energetic resources in response to sensory information (associated with ADHD), and atypical electrophysiological indices of information processing (associated with autism), might negatively affect cognitive performance in those with ADHD+autism.

Stress System Activation in Children and Adolescents With Autism Spectrum Disorder

The mission of the human stress system is the maintenance of homeostasis in the presence of real or perceived, acute or chronic stressors. The hypothalamic–pituitary–adrenal (HPA) axis and the autonomic nervous system (ANS) are the stress system-related neuroendocrine pathways. There is abundant evidence that children and adolescents with autism spectrum disorder (ASD) may exhibit atypical function within the HPA axis and the ANS both at the resting state and during the presence of social and/or non-social stressors. The aim of this review is to provide an up-to-date summary of the findings regarding stress system alterations in children and adolescents with ASD. We focus on the variations of stress hormones circadian rhythms, specifically cortisol and alpha-amylase (i.e., a surrogate index of epinephrine/norepinephrine secretion), and on the alterations of stress system responsivity to different stressors. Also, we present imaging and immunological findings that have been associated with stress system dysregulation in children and adolescents with ASD. Finally, we review the pivotal role of HPA axis-ANS coordination, the developmental trajectory of the stress system in ASD, and the possible role of early life stress in the dysregulation of the stress system demonstrated in children and adolescents with ASD. This synthesis will hopefully provide researchers with a foundation for an integrated approach to future research into stress system variations in children and adolescents with ASD.

Autism Spectrum Disorder in Children Is Not Associated With Abnormal Autonomic Nervous System Function: Hypothesis and Theory

The quest to understand the pathophysiology of autism spectrum disorder (ASD) has led to extensive literature that purports to provide evidence for autonomic dysfunction based on heart rate and heart rate variability (HRV), in particular respiratory sinus arrhythmia (RSA), a measure of parasympathetic functioning. Many studies conclude that autism is associated with vagal withdrawal and sympathetic hyperactivation based on HRV and electrodermal analyses. We will argue that a critical analysis of the data leads to the hypothesis that autonomic nervous system dysfunction is not a dominant feature of autism. Most children with ASD have normal parasympathetic baseline values and normal autonomic responses to social stimuli. The existing HRV and electrodermal data cannot lead to the conclusion of an over-excitation of the sympathetic nervous system. A small subgroup of ASD children in experimental settings has relatively low RSA values and relatively high heart rates. The data suggest that this is likely associated with a relatively high level of anxiety during study conditions, associated with co-morbidities such as constipation, or due to the use of psychoactive medication. Many studies interpret their data to conform with a preferred hypothesis of autonomic dysfunction as a trait of autism, related to the polyvagal theory, but the HRV evidence is to the contrary. HRV analysis may identify children with ASD having autonomic dysfunction due to co-morbidities.

Evaluating the potential of respiratory-sinus-arrhythmia biofeedback for reducing physiological stress in adolescents with autism: study protocol for a randomized controlled trial

Background

Prior evidence points towards lower cardiac vagal modulation in individuals with autism spectrum disorder (ASD) as compared to control groups. A cross-sectional phase in this study will gather more evidence concerning this topic. A longitudinal phase will explore the efficacy of a biofeedback intervention based on respiratory sinus arrhythmia (RSA) in adolescents with ASD. Finally, a feasibility study will focus on a non-supervised RSA biofeedback intervention in this population.

Methods

The cross-sectional phase includes the comparison of adolescents with ASD (n=38) and age- and gender-matched typically developing peers. A standardized assessment will be used which contains physiological, cortisol, and behavioral measurements. The longitudinal phase contains a randomized, single-blinded, and sham-controlled design to determine the efficacy of supervised RSA biofeedback in adolescents with ASD (n=128). A follow-up phase of 5 weeks is included to evaluate the presence of retention effects. During the latter, a feasibility study will focus on a non-supervised intervention (n=64). Assessments as described previously are scheduled after the intervention and the follow-up phase.

Discussion

First, more conclusive evidence will be provided for the presence of lower cardiac vagal modulation in adolescents with ASD as well as the association between these lower values and physiological and behavioral indices. Second, the supervised intervention in adolescents with ASD is hypothesized to upregulate this cardiac vagal modulation and positively change behavioral and physiological parameters. Third, evidence regarding the feasibility and acceptability of a non-supervised intervention may open novel avenues for home-based interventions in this population.

Trial registration

ClinicalTrials.govNCT04628715. Registered on 13 November 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05709-4.

Alternations in the Cardiovascular Autonomic Regulation and Growth Factors in Autism

Autism spectrum disorder (ASD) represents a serious neurodevelopmental disorder associated with autonomic nervous system dysregulation. The aim was to study complex cardiovascular autonomic regulation using heart rate variability (HRV) and systolic blood pressure variability (SBPV) linear/non-linear analysis at rest and during orthostasis, and to assess plasma levels of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) in autistic children. Twenty-five ASD boys and 25 age and gender-matched children at the age 7-15 years were examined. After venous blood taking, continuous ECG and blood pressure biosignals were recorded at rest and during orthostasis. Evaluated parameters: RR intervals, high- and low-frequency band of HRV spectral analysis (HF-HRV, LF-HRV), symbolic dynamics parameters 0V%, 1V%, 2LV%, 2UV%, low- and high-frequency band of SBPV (LF-SBPV, HF-SBPV), systolic, diastolic, mean blood pressure, EGF, VEGF plasma levels. RR intervals were significantly shortened and the HF-HRV, LF-SBPV, HF-SBPV parameters were significantly lower at rest, the HF-HRV and LF-SBPV remained lower during orthostasis in autistic children compared to controls (p<0.05). EGF plasma levels were significantly lower in ASD compared to controls (p=0.046). No significant differences were found in remaining parameters. Our study revealed tachycardia, cardiovagal underactivity, and blunted sympathetic vasomotor regulation at rest and during orthostasis in autistic children. Additionally, complex heart rate dynamics are similar in autistic children than controls. Furthermore, EGF was reduced in autistic children without significant correlations with any autonomic parameters. We suggest that the abnormal complex cardiovascular reflex control could contribute to understanding the pathway linking autonomic features and autism.

The process of Learn to Play Therapy with parent-child dyads with children who have autism spectrum disorder

INTRODUCTION

Learn to Play Therapy aims to build children's ability to spontaneously initiate pretend play. The purpose of this study was to explore evidence for this therapy for children with autism spectrum disorder by investigating the changes in a child's pretend play and key techniques used in the process of therapy.

METHODS

Six children with a diagnosis of autism spectrum disorder (mean age = 3.8 years; SD = 1.2 years) were engaged in therapy sessions with a parent. Four therapy session videos for each child were selected across four time points from 15 videos of each child, representing 6 months of therapy. Retrospective video analysis was used to investigate the changes in the child's ability by coding six play skills and enjoyment of play. Key techniques in the process of Learn to Play Therapy were analysed by frequency of occurrence during sessions.

RESULTS

There was a significant increase in the child's pretend play ability for play scripts (p = .042), sequences of play actions (p = .043), object substitution (p = .043), doll/teddy play (p = .028), social interaction (p = .043) and enjoyment (p = .026). There was a mirroring of the therapist, parent and child for all key techniques, with parents showing increased frequency rates after Time 1. Repetition with variation decreased by Time 4. Challenging the child showed higher rates in Times 2 and 4. Focussed attention remained stable, and the child's talk during play had the highest total frequency.

CONCLUSION

Learn to Play Therapy is an effective therapy in building pretend play ability in children with autism, with parents increasing their involvement in using the key techniques after Time 1. The results inform therapists on how the key techniques were used within the therapy sessions to increase the child's pretend play ability.

Executive Functioning: A Mediator Between Sensory Processing and Behaviour in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interaction, executive functioning, sensory-perceptual abilities and behaviour, such as anxious/depressed states, attention problems, aggression, or somatic complains. However, the dynamic relationship between these dimensions remains to be addressed. Therefore, we explored the link between executive functions, sensory processing and behaviour in 79 children and adolescents with ASD. Results showed significant associations between all dimensions-executive functions, sensory processing and behaviour. Furthermore, using structural equation modelling methods, we observed a mediation effect of executive functioning, specifically the domain pertaining to emotion regulation and control, and in the relationship between sensory processing abnormalities and behavioural problems. We discuss the importance of emotion regulation as a mediator between sensory processing and behavioural impairments and its impact in social competence in ASD.

Technology-Based Assessments and Treatments of Anxiety in Autistic Individuals: Systematic Review and Narrative Synthesis

This systematic review (Prospero Registration Number: CRD42019142910) aimed to narratively synthesise technology-aided assessments and treatments of anxiety in individuals with autism spectrum disorder (ASD) for the first time. Sixteen studies were identified: 5 assessment studies and 11 treatment studies. Assessment studies targeted state anxiety using ecological momentary assessment, wearables, or computerised tasks. Treatment studies targeted specific fears/phobias using electronic screen media or transdiagnostic anxiety using telemedicine. Broadly, results indicated technology-aided assessments and treatments may be feasible and effective at targeting anxiety in ASD, except treatments involving social scripts or peer modelling. Assessment results further indicated that state anxiety in ASD has a distinct psychophysiological signature and is evoked by idiosyncratic triggers. However, larger scale studies with representative samples are needed.

Heart Rate Variability Biofeedback Improves Emotional and Physical Health and Performance: A Systematic Review and Meta Analysis

We performed a systematic and meta analytic review of heart rate variability biofeedback (HRVB) for various symptoms and human functioning. We analyzed all problems addressed by HRVB and all outcome measures in all studies, whether or not relevant to the studied population, among randomly controlled studies. Targets included various biological and psychological problems and issues with athletic, cognitive, and artistic performance. Our initial review yielded 1868 papers, from which 58 met inclusion criteria. A significant small to moderate effect size was found favoring HRVB, which does not differ from that of other effective treatments. With a small number of studies for each, HRVB has the largest effect sizes for anxiety, depression, anger and athletic/artistic performance and the smallest effect sizes on PTSD, sleep and quality of life. We found no significant differences for number of treatment sessions or weeks between pretest and post-test, whether the outcome measure was targeted to the population, or year of publication. Effect sizes are larger in comparison to inactive than active control conditions although significant for both. HRVB improves symptoms and functioning in many areas, both in the normal and pathological ranges. It appears useful as a complementary treatment. Further research is needed to confirm its efficacy for particular applications.

Autism and mood disorders

Individuals with autism experience substantially higher rates of mood problems compared to the general population, which contribute to reduced quality of life and increased mortality through suicide. Here, we reviewed evidence for the clinical presentation, aetiology and therapeutic approaches for mood problems in autism. We identified a lack of validated tools for accurately identifying mood problems in individuals with autism, who may present with 'atypical' features (e.g. severe irritability). Risk factors for mood problems in autism appear to be largely overlapping with those identified in the general population, including shared genetic, environmental, cognitive, physiological/neurobiological mechanisms. However, these mechanisms are exacerbated directly/indirectly by lived experiences of autism, including increased vulnerability for chronic stress - often related to social-communication difficulties(/bullying) and sensory sensitivities. Lastly, current therapeutic approaches are based on recommendations for primary mood disorders, with little reference to the neurobiological/cognitive differences associated with autism. Thus, we recommend: 1) the development and validation of (objective) tools to identify mood problems in autism and measure therapeutic efficacy; 2) an interactive approach to investigating aetiologies in large-scale longitudinal studies, integrating different levels of analysis (e.g. cognitive, neurobiological) and lived experience; 3) testing potential treatments through high-quality (e.g. sufficiently powered, blinded) clinical trials, specifically for individuals with autism.

Exploring Social Biomarkers in High-Functioning Adults with Autism and Asperger's Versus Healthy Controls: A Cross-Sectional Analysis

Biomarkers for autism spectrum disorder (ASD) are lacking but would facilitate drug development for the core deficits of the disorder. We evaluated markers proposed for characterization of differences in social communication and interaction in adults with ASD versus healthy controls (HC) for utility as biomarkers. Data pooled from an observational study and baseline data from a placebo-controlled study were analyzed. Between-group differences were observed in eye-tracking tasks for activity monitoring, biomotion, human activity preference, composite score (p = 0.0001-0.037) and pupillometry (various tasks, p = 0.017-0.05). Impaired olfaction was more common in the ASD sample versus HC (p = 0.018). Our preliminary results suggest the potential use for stratification and response sub-analyses outcome-prediction of specific eye-tracking tasks, pupillometry and olfaction tests in ASD trials.

Differential Item Functioning Based on Autism Features, IQ, and Age on the Screen for Child Anxiety Related Disorders (SCARED) Among Youth on the Autism Spectrum

Anxiety commonly occurs among youth on the autism spectrum, yet measurement of anxiety in this population is complicated by a number of factors, including potentially overlapping symptomatology, the child's intellectual functioning, and changes in anxiety across development. Moreover, few studies have examined the psychometric properties of anxiety measures in this population, and no study to date has tested whether there are systematic differences in the measurement of anxiety, or differential item functioning (DIF), across the high degree of heterogeneity and the developmental course of autism. To test this possibility, data were combined across multiple studies using the National Database for Autism Research, an NIH-funded data repository. Parent-report on the Screen for Child Anxiety Related Disorders (SCARED) and Social Communication Questionnaire (SCQ) were used as measures of anxiety and autism features, respectively. A confirmatory factor analysis indicated good fit of the literature standard five-factor structure. Moderated nonlinear factor analysis (MNLFA) revealed multiple items with intercept and loading DIF based on level of autism features, IQ, and age, especially for items related to social behavior. Therefore, although the measure's factor structure is consistent with that found in the general population, the SCARED may not capture differences in anxiety equivalently for all children on the spectrum and across their development. Clinicians and researchers need to be especially vigilant in measuring anxiety symptoms in children with autism by removing items flagged for DIF from the SCARED and/or by using multiple measures and informants. LAY ABSTRACT: Autistic youth often experience clinical levels of anxiety. Many tools used to measure anxiety were developed for the general population, but not for use with autistic youth. This study found that the Screen for Child Anxiety Related Disorders (SCARED) measures the same five dimensions of anxiety as in the general population. Parents, however, may respond differently to questions on the SCARED based on their child's autism features, intellectual functioning, and age, which impacts our ability to accurately measure anxiety among autistic youth.

Gaze Following and Pupil Dilation as Early Diagnostic Markers of Autism in Toddlers

Background: Children with autism spectrum disorder (ASD) show certain characteristics in visual attention. These may generate differences with non-autistic children in the integration of relevant social information to set the basis of communication. Reliable and objective measurement of these characteristics in a language learning context could contribute to a more accurate early diagnosis of ASD. Gaze following and pupil dilation are being studied as possible reliable measures of visual attention for the early detection of ASD. The eye-tracking methodology allows objective measurement of these biomarkers. The aim of this study is to determine whether measurements of gaze following and pupillary dilation in a linguistic interaction task are potential objective biomarkers for the early diagnosis of ASD. Method: A group of 20 children between 17 and 24 months of age, made up of 10 neurotypical children (NT) and 10 children with an increased likelihood of developing ASD were paired together according to chronological age. A human face on a monitor pronounced pseudowords associated with pseudo-objects. Gaze following and pupil dilation were registered during the task These measurements were captured using eye-tracking methodology. Results: Significant statistical differences were found in the time of gaze fixation on the human face and on the object, as well as in the number of gazes. Children with an increased possibility of developing ASD showed a slightly higher pupil dilation than NT children. However, this difference was not statistically significant. Nevertheless, their pupil dilation was uniform throughout the different periods of the task while NT participants showed greater dilation on hearing the pseudoword. Conclusions: The fixing and the duration of gaze, objectively measured by a Tobii eye-tracking system, could be considered as potential biomarkers for early detection of ASD. Additionally, pupil dilation measurement could reflect differential activation patterns during word processing in possible ASD toddlers and NT toddlers.

Relationships among gastrointestinal symptoms, sleep problems, challenging behaviour, comorbid psychopathology and autism spectrum disorder symptoms in children and adolescents with 15q duplication syndrome

BACKGROUND

Comorbidity is the presence of at least two disorders in one person at one time. This study examined the frequency of gastrointestinal (GI) symptoms, sleep problems, comorbid psychopathology, challenging behaviour and autism spectrum disorder (ASD) symptoms in children and adolescents with duplication 15q syndrome (Dup15q), aged 3-17 years. This study also examined whether challenging behaviour in Dup15q is predicted by age, gender, presence of an intellectual disability, sleep problems, GI symptoms and comorbid psychopathology.

METHOD

Parental measures were completed by 101 parents of children and adolescents with Dup15q. Questionnaires were composed of the Children's Sleep Habits Questionnaire, Behavior Problems Inventory - Short Form, GI Symptom Inventory, Social Communication Questionnaire and the Child Behavior Checklist.

RESULTS

Sleep problems (94%), GI symptoms (87%) and challenging behaviour (100%) were common comorbidities represented in the sample in this study. Significant relationships were found between challenging behaviour and the presence of co-occurring sleep problems, GI symptoms, comorbid psychopathology and ASD symptoms. Further analysis revealed that these comorbidities also predicted challenging behaviour.

CONCLUSION

This research demonstrated the importance of studying the relationships between GI symptoms, sleep problems, comorbid psychopathology, ASD symptoms and challenging behaviour in Dup15q and how these conditions can shape the Dup15q phenotype.

Brief Report: Can a Composite Heart Rate Variability Biomarker Shed New Insights About Autism Spectrum Disorder in School-Aged Children?

Several studies show altered heart rate variability (HRV) in autism spectrum disorder (ASD), but findings are neither universal nor specific to ASD. We apply a set of linear and nonlinear HRV measures-including phase rectified signal averaging-to segments of resting ECG data collected from school-age children with ASD, age-matched typically developing controls, and children with other psychiatric conditions characterized by altered HRV (conduct disorder, depression). We use machine learning to identify time, frequency, and geometric signal-analytical domains that are specific to ASD (receiver operating curve area = 0.89). This is the first study to differentiate children with ASD from other disorders characterized by altered HRV. Despite a small cohort and lack of external validation, results warrant larger prospective studies.

Cardiac Startle Response and Clinical Outcomes in Preschool Children With Fragile X Syndrome and Autism Spectrum Disorder

Objective: Poor physiological regulation in response to threat is linked to multiple negative developmental outcomes including anxiety, which is highly prevalent and impairing in young children with neurodevelopmental disabilities like fragile X syndrome (FXS) and autism spectrum disorder (ASD). The present study contrasted cardiac startle response in pre-school-aged children with FXS, with and without ASD, to children with non-syndromic ASD (nsASD) and neurotypical controls (NT). The relationship of cardiac startle to non-verbal mental age (NVMA), ASD severity, and parent-reported anxiety was also examined. Method: Four age-matched groups of pre-school children participated including those with FXS without ASD (FXS-Only, n = 21), FXS with ASD (FXS+ASD, n = 17), nsASD (n = 42), and NT children (n = 27). Participants viewed a silent movie during which a single 200 ms 98-decibel white noise burst occurred. Cardiac activity was analyzed for pre-stimulus respiratory sinus arrhythmia (RSA) and the inter-beat intervals (IBI) at the auditory stimulus and 10 s post-stimulus. The Spence Pre-school Anxiety Scale, Autism Diagnostic Observation Schedule-2nd Edition, and Mullen Scales of Early Learning were examined in relation to startle response. Results: The nsASD group demonstrated heightened cardiac activity at the auditory stimulus and 10 s post-stimulus compared to the NT controls. Neither of the FXS groups showed differences from any other group. Higher pre-stimulus RSA was associated with reduced cardiac response across groups, while the relationship between cognitive ability and ASD severity to cardiac response varied between groups. Parent-reported anxiety was not associated with cardiac response for any group. Conclusion: These findings demonstrate group distinctions in cardiac responses to auditory startle. Although FXS and ASD share behavioral characteristics, the nsASD group showed a heightened cardiac startle response compared to the NT group that was not present in the FXS groups with or without ASD. Non-verbal mental age was associated with greater stimulus or post-stimulus reactivity for all groups except the FXS+ASD group, which showed no association between startle response and any clinical outcomes. Increased understanding of the relationship between physiological regulation and clinical outcomes will assist in identifying the timing and targets for effective interventions for individuals with neurodevelopmental disabilities.

Trajectories of Heart Activity Across Infancy to Early Childhood Differentially Predict Autism and Anxiety Symptoms in Fragile X Syndrome

Background: Fragile X syndrome (FXS) is a monogenic disorder characterized by high rates of autism spectrum disorder (ASD) and anxiety. A longstanding "hyperarousal hypothesis" in FXS has argued that ANS dysfunction underpins many symptoms of FXS. However, the developmental onset and trajectory of ANS dysfunction, as well as the consequences of ANS dysfunction on later psychiatric symptoms, remain poorly understood in FXS. Insight into the emergence, trajectory, and consequences of ANS dysfunction across early development in FXS has critical implications for prevention, intervention, and optimal outcomes in both typical and atypical development. This longitudinal study investigated whether and when males with FXS evidence atypical ANS function from infancy through early childhood, and how trajectories of ANS function across infancy and early childhood predict ASD and anxiety symptom severity later in development. Methods: Participants included 73 males with FXS and 79 age-matched typically developing (TD) males. Baseline heart activity was recorded at multiple assessments between 3 and 83 months of age, resulting in 372 observations. General arousal and parasympathetic activity were indexed via interbeat interval (IBI) and respiratory sinus arrhythmia (RSA), respectively. ASD and anxiety symptoms were assessed at 36 months of age or later in a subgroup of participants (FXS n = 28; TD n = 25). Results: Males with FXS exhibited atypical patterns of developmental change in ANS function across infancy and early childhood. As a result, ANS dysfunction became progressively more discrepant across time, with the FXS group exhibiting significantly shorter IBI and lower RSA by 29 and 24 months of age, respectively. Shorter IBI at 24 months and a flatter IBI slope across development predicted elevated anxiety symptoms, but not ASD symptoms, later in childhood in both FXS and TD males. Reduced RSA at 24 months predicted elevated ASD symptoms, but not anxiety symptoms, in both groups. Developmental change in RSA across early development did not predict later anxiety or ASD symptoms. Conclusion: This is the first longitudinal study to examine the "hyperarousal hypothesis" in infants and young children with FXS. Findings suggest that hyperarousal (i.e., shorter IBI, lower RSA) is evident in males with FXS by 24-29 months of age. Interestingly, unique aspects of early ANS function differentially relate to later ASD and anxiety symptoms. General arousal, indexed by shorter IBI that becomes progressively more discrepant from TD controls, predicts later anxiety symptoms. In contrast, parasympathetic-related factors, indexed by lower levels of RSA, predict ASD symptoms. These findings support the "hyperarousal hypothesis" in FXS, in that ANS dysfunction evident early in development predicts later-emerging symptoms of ASD and anxiety. This study also have important implications for the development of targeted treatments and interventions that could potentially mitigate the long-term effects of hyperarousal in FXS.

Prepronociceptin-Expressing Neurons in the Extended Amygdala Encode and Promote Rapid Arousal Responses to Motivationally Salient Stimuli

Motivational states consist of cognitive, emotional, and physiological components controlled by multiple brain regions. An integral component of this neural circuitry is the bed nucleus of the stria terminalis (BNST). Here, we identify that neurons within BNST that express the gene prepronociceptin (Pnoc^BNST) modulate rapid changes in physiological arousal that occur upon exposure to motivationally salient stimuli. Using in vivo two-photon calcium imaging, we find that Pnoc^BNST neuronal responses directly correspond with rapid increases in pupillary size when mice are exposed to aversive and rewarding odors. Furthermore, optogenetic activation of these neurons increases pupillary size and anxiety-like behaviors but does not induce approach, avoidance, or locomotion. These findings suggest that excitatory responses in Pnoc^BNST neurons encode rapid arousal responses that modulate anxiety states. Further histological, electrophysiological, and single-cell RNA sequencing data reveal that Pnoc^BNST neurons are composed of genetically and anatomically identifiable subpopulations that may differentially tune rapid arousal responses to motivational stimuli.

Emergence and rate of autism in fragile X syndrome across the first years of life

Prospective longitudinal studies of idiopathic autism spectrum disorder (ASD) have provided insights into early symptoms and predictors of ASD during infancy, well before ASD can be diagnosed at age 2-3 years. However, research on the emergence of ASD in disorders with a known genetic etiology, contextualized in a developmental framework, is currently lacking. Using a biobehavioral multimethod approach, we (a) determined the rate of ASD in N = 51 preschoolers with fragile X syndrome (FXS) using a clinical best estimate (CBE) procedure with differential diagnoses of comorbid psychiatric disorders and (b) investigated trajectories of ASD symptoms and physiological arousal across infancy as predictors of ASD in preschoolers with FXS. ASD was not diagnosed if intellectual ability or psychiatric disorders better accounted for the symptoms. Our results determined that 60.7% of preschoolers with FXS met the Diagnostic and Statistical Manual of Mental Disorders (fifth edition) (DSM-5) criteria for ASD using the CBE procedure. In addition, 92% of these preschoolers presented with developmental delay and 45.4% also met criteria for psychiatric disorders, either anxiety, ADHD, or both. ASD diagnoses in preschoolers with FXS were predicted by elevated scores on traditional ASD screeners in addition to elevated autonomic arousal and avoidant eye contact from infancy.

A wearable heart rate measurement device for children with autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by early impairment in social and communication domains and autonomic nervous system unbalance. This study evaluated heart rate (HR) as a possible indicator of stress response in children with ASD as compared to children with language disorder (LD). Twenty-four patients [mean age = 42.62 months; SD = 8.14 months,12 with ASD (10 M/2F) and 12 with LD (8 M/4F)] underwent clinical [Leiter International Performance Scale-Revised, Autism Diagnostic Observation Schedule, second edition (ADOS-2)] and physiological evaluation (HR monitoring) during five interactive activities, while wearing an HR measurement device. IQ (ASD:IQ = 103.33 ± 12.85 vs. LD:IQ = 111.00 ± 8.88, p = 0.103) and fluid reasoning on the Leiter-R Scale were within the normal range in all subjects. Increased HR during the third activity (ADOS-2 bubble play) significantly correlated with autistic symptoms (r = 0.415; p = 0.044), while correlations between ADOS-2 total score and HR during the first activity (ADOS-2 free play; r = 0.368; p = 0.077), second activity (Leiter-R figure ground subscale; r = 0.373, p = 0.073), and fifth activity (ADOS-2 anticipation of a routine with objects; r = 0.368; p = 0.076) did not quite reach statistical significance. Applying a linear regression model, we found that the ADOS-2 total score significantly influenced HR variations (p = 0.023). HR monitoring may provide a better understanding of the stress-provoking situations for children with ASD. Furthermore, it could help clinicians detect the impact of the stressful condition on the autistic core and adress treatment strategy.

Autism spectrum disorder and pupillometry: A systematic review and meta-analysis

Pupillometry, measuring pupil size and reactivity, has been proposed as a measure of autonomic nervous system functioning, the latter which might be altered in individuals with autism spectrum disorder (ASD). This study aims to evaluate if pupillary responses differ in individuals with and without ASD. After performing a systematic literature search, we conducted a meta-analysis and constructed a qualitative synthesis. The meta-analysis shows a longer latency of the pupil response in the ASD-group as a substantial group difference, with a Hedges' g of 1.03 (95% CI 0.49-1.56, p = 0.008). Evidence on baseline pupil size and amplitude change is conflicting. We used the framework method to perform a qualitative evaluation of these differences. Explanations for the group differences vary between studies and are inconclusive, but many authors point to involvement of the autonomous nervous system and more specifically the locus coeruleus-norepinephrine system. Pupillometry reveals differences between people with and without ASD, but the exact meaning of these differences remains unknown. Future studies should align research designs and investigate a possible effect of maturation.

PRESS-Play: Musical Engagement as a Motivating Platform for Social Interaction and Social Play in Young Children with ASD

Musical experiences are ubiquitous in early childhood. Beyond potential benefits of musical activities for young children with typical development, there has long been interest in harnessing music for therapeutic purposes for individuals with autism spectrum disorder (ASD). However, there is debate as to the effectiveness of these approaches and thus a need to identify mechanisms of change (or active ingredients) by which musical experiences may impact social development in young children with ASD. In this review, we introduce the PRESS-Play framework, which conceptualizes musical activities for young children with ASD within an applied behavior analysis framework consistent with the principles of naturalistic developmental behavioral interventions. Specifically, the PRESS-Play framework proposes that musical activities support key elements of evidence-based approaches for social engagement including predictability, reinforcement, emotion regulation, shared attention, and social play context, providing a platform for delivery and receipt of social and behavioral instruction via a transactional, developmental approach. PRESS-Play considers that these factors may impact not only the child with ASD but also their interaction partner, such as a parent or peer, creating contexts conducive for validated social engagement and interaction. These principles point to focused theories of change within a clinical-translational framework in order to experimentally test components of social-musical engagement and conduct rigorous, evidence-based intervention studies.

Emerging biomarkers in autism spectrum disorder: a systematic review

Autism spectrum disorder (ASD) affects approximately 2% of children in the United States (US) yet its etiology is unclear and effective treatments are lacking. Therapeutic interventions are most effective if started early in life, yet diagnosis often remains delayed, partly because the diagnosis of ASD is based on identifying abnormal behaviors that may not emerge until the disorder is well established. Biomarkers that identify children at risk during the pre-symptomatic period, assist with early diagnosis, confirm behavioral observations, stratify patients into subgroups, and predict therapeutic response would be a great advance. Here we underwent a systematic review of the literature on ASD to identify promising biomarkers and rated the biomarkers in regards to a Level of Evidence and Grade of Recommendation using the Oxford Centre for Evidence-Based Medicine scale. Biomarkers identified by our review included physiological biomarkers that identify neuroimmune and metabolic abnormalities, neurological biomarkers including abnormalities in brain structure, function and neurophysiology, subtle behavioral biomarkers including atypical development of visual attention, genetic biomarkers and gastrointestinal biomarkers. Biomarkers of ASD may be found prior to birth and after diagnosis and some may predict response to specific treatments. Many promising biomarkers have been developed for ASD. However, many biomarkers are preliminary and need to be validated and their role in the diagnosis and treatment of ASD needs to be defined. It is likely that biomarkers will need to be combined to be effective to identify ASD early and guide treatment.