Brief Report: Reduced Heart Rate Variability in Children with Autism Spectrum Disorder

Autonomic and hedonic response to affective touch in autism spectrum disorder

Interpersonal touch plays a crucial role in shaping relationships and encouraging social connections. Failure in processing tactile input or abnormal tactile sensitivity may hamper social behaviors and have severe consequences in individuals' relational lives. Autism Spectrum Disorder (ASD) is characterized by both sensory disruptions and social impairments, making affective touch an ideal meeting point for understanding these features in ASD individuals. By integrating behavioral and physiological measures, we investigated the effects of affective touch on adult individuals with ASD from both an implicit and explicit perspective. Specifically, at an implicit level, we investigated whether and how receiving an affective touch influenced participants' skin conductance tonic and phasic components. At the explicit level, we delved into the affective and unpleasant features of affective touch. Overall, we observed lower skin conductance level in ASD compared to TD subjects. Interestingly, the typically developing (TD) group showed an increased autonomic response for affective touch compared to a control touch, while ASD subjects' autonomic response did not differ between the two conditions. Furthermore, ASD participants provided higher ratings for both the affective and unpleasant components of the touch, compared to TD subjects. Our results reveal a noteworthy discrepancy in ASD population between the subjective experience, characterized by amplified hedonic but also unpleasant responses, and the physiological response, marked by a lack of autonomic activation related to affective touch. This insightful dissociation seems crucial for a deeper understanding of the distinctive challenges characterizing people with ASD and may have implications for diagnosis and therapeutic approaches.

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.

Pre-autism: What a paediatrician should know about early diagnosis of autism‎

Autism, also known as an autism spectrum disorder, is a complex neurodevelopmental disorder usually diagnosed in the first three years of a child's life. A range of symptoms characterizes it and can be diagnosed at any age, including adolescence and adulthood. However, early diagnosis is crucial for effective management, prognosis, and care. Unfortunately, there are no established fetal, prenatal, or newborn screening programs for autism, making early detection difficult. This review aims to shed light on the early detection of autism prenatally, natally, and early in life, during a stage we call as "pre-autism" when typical symptoms are not yet apparent. Some fetal, neonatal, and infant biomarkers may predict an increased risk of autism in the coming baby. By developing a biomarker array, we can create an objective diagnostic tool to diagnose and rank the severity of autism for each patient. These biomarkers could be genetic, immunological, hormonal, metabolic, amino acids, acute phase reactants, neonatal brainstem function biophysical activity, behavioral profile, body measurements, or radiological markers. However, every biomarker has its accuracy and limitations. Several factors can make early detection of autism a real challenge. To improve early detection, we need to overcome various challenges, such as raising community awareness of early signs of autism, improving access to diagnostic tools, reducing the stigma attached to the diagnosis of autism, and addressing various culturally sensitive concepts related to the disorder.

Neurobehavioral and Medical Correlates of Autism Screening: 2-Year Outcomes for Infants Born Very Preterm

OBJECTIVE

To identify neonatal characteristics and 2-year neurodevelopmental outcomes associated with positive screening for risk of autism.

STUDY DESIGN

Nine university-affiliated neonatal intensive care units (NICUs) enrolled infants born at <30 weeks of gestation. Infants underwent the NICU Network Neurobehavioral Scale examination before discharge and the Bayley Scales of Infant and Toddler Development, Third Edition, the Child Behavior Checklist, and the Modified Checklist for Autism in Toddlers, revised with follow-up (M-CHAT-R/F) at 2 years of corrected age. Generalized estimating equations examined associations between M-CHAT-R/F, neurobehavioral test results, and neonatal medical morbidities.

RESULTS

At 2 years of corrected age, data were available for 466 of 744 enrolled infants without cerebral palsy. Infants with hypoaroused NICU Network Neurobehavioral Scale profiles were more likely to screen M-CHAT-R/F-positive (OR 2.76, 95% CI 1.38-5.54). Infants with ≥2 medical morbidities also were more likely to screen positive (OR 2.65, 95% CI 1.27-5.54). Children with positive M-CHAT-R/F scores had lower Bayley Scales of Infant and Toddler Development, Third Edition, Cognitive (t [451] = 5.43, P < .001, d = 0.82), Language (t [53.49] = 7.82, P < .001, d = 1.18), and Motor (t [451] = 7.98, P < .001, d = 1.21) composite scores and significantly greater Child Behavior Checklist Internalizing (t [457] -6.19, P < .001, d = -0.93) and Externalizing (t [57.87] = -5.62, P < .001, d = -0.84) scores.

CONCLUSIONS

Positive M-CHAT-R/F screens at 2 years of corrected age were associated with neonatal medical morbidities and neurobehavioral examinations as well as toddler developmental and behavioral outcomes. These findings demonstrate the potential utility of the M-CHAT-R/F as a global developmental screener in infants born very preterm, regardless of whether there is a later autism diagnosis.

Motor Skills, Heart Rate Variability, and Arterial Stiffness in Children with Autism Spectrum Disorder

The prevalence of autism spectrum disorder (ASD) among children has been recently increasing. The severity of symptoms greatly varies between individuals with ASD, ranging from relatively mild to extremely severe. It is important to have a clearer understanding of the possible adverse consequences resulting from this disorder, such as delayed motor development, autonomic dysregulation, and arterial stiffness. Thus, the objective of this study was to investigate differences in motor skills, heart rate variability (HRV), and arterial stiffness between children with ASD and typically developing children. In this study, the school-aged children with mild symptoms of ASD (n = 17, 11.1 ± 1.0 years old) and typically developing peers (n = 15, 11.0 ± 0.5 years old) were recruited. Motor skills, HRV, and arterial stiffness were measured in these two groups. Motor skills were evaluated by the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition. Moreover, HRV was measured through a short-term recording using the Polar heart rate monitor, and arterial stiffness was assessed by non-invasive computerized oscillometry. Compared with the typically developing group, children with ASD displayed significant deficits in some areas of motor skills, including manual coordination, strength and agility, and total motor composite. Moreover, children with ASD exhibited significantly reduced HRV, including time- and frequency-domain measures. However, the results did not demonstrate any statistically significant differences in arterial stiffness between the groups. Our findings demonstrated the presence of motor skill deficits and autonomic dysregulation in children with ASD.

Temporal profile of intranasal oxytocin in the human autonomic nervous system at rest: An electrocardiography and pupillometry study

BACKGROUND

Human social behavior is modulated by oxytocin (OT). Intranasal administration of OT (IN-OT) is a noninvasive route shown to elicit changes in the autonomic nervous system (ANS) activity; however, IN-OT's effect on the temporal profile of ANS activity at rest is yet to be described.

AIMS

We aimed to describe the temporal profile of IN-OT at six 10-min time windows from 15- to 100-min post-administration in 20 male participants at rest while continuously recording their pupillary in an eyes-open condition and cardiac activity in eyes-open and eyes-closed conditions.

METHODS

We used a double-blind, placebo-controlled, within-subjects design study where we extracted two proxies of parasympathetic nervous system (PNS) activity: high-frequency heart rate variability (HF-HRV) and pupillary unrest index (PUI); and a proxy of sympathetic nervous system activity: sample entropy of the pupillary unrest.

RESULTS

In the eyes-open condition, we found an effect of IN-OT on the proxies of PNS activity: decreased PUI in the three-time windows post-administration spanning 65-100 min, and as an exploratory finding, an increased HF-HRV in the 80-85 min time window.

CONCLUSIONS

We suggest there is a role of OT in PNS regulation that may be consistent with OT's currently theorized role in the facilitation of alertness and approach behavior.

Physiological and Psychological Effects of Parent-Delivered Traditional Thai Massage in Children With Autism: Protocol for a Randomized Controlled Trial

BACKGROUND

Although many autistic children receive massage as a complementary therapy, it is not included in evidence-based practice for autism because evidence of its efficacy is lacking. Further, prior studies have failed to identify objective indicators of core symptoms or elucidate their mechanisms.

OBJECTIVE

We developed a parent-delivered traditional Thai massage (TTM) intervention for children with autism, aiming to experimentally determine whether children with autism truly experience positive effects from parent-delivered TTM and determine possible mechanisms of the observed effects.

METHODS

A 2-armed, parallel randomized controlled trial was conducted between February 2022 and June 2022. Forty-eight children with autism (aged 7-12 years) were recruited from the Hainan Special Education School and randomly assigned to either a parental TTM or control group at a ratio of 1:1 based on random numbers generated with Online Research Randomizer. The generated sequences were concealed in an opaque envelope. Individuals in the parental TTM group received 16 parent-delivered TTM sessions over 8 weeks at the school's health room after school, and the control group maintained a normal daily routine. Outcomes were assessed on admission, after 8 weeks, and at a 2-month follow-up and included the effect of massage treatment on autism symptoms, measured with the Autism Treatment Evaluation Checklist score (evaluated by parents and a blinded teacher), physiological parameters (ie, heart rate variability and gait), and the Parenting Stress Index, Fourth Edition-Short Form.

RESULTS

We finished all data collection on June 20, 2022. Data analysis will be started, and we expect to publish results in 2023.

CONCLUSIONS

This study will provide further evidence for massage treatment of autism and provide support for family-based care.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100051355; https://tinyurl.com/3dwjxsw5.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41839.

Exploring Subtypes of Repetitive Behavior in Children with Autism Through Functional Analysis and Wearable Technology: a Pilot Biobehavioral Assessment

Objectives

Prior research has established assessment methodologies, such as functional analysis to identify specific contexts in which restricted and repetitive behavior (RRB) occurs, and measures of heart rate variability (HRV) to index the level of autonomic arousal in individuals with autism spectrum disorder (ASD). Yet, a gap remains in integrating multiple assessment methodologies to examine the complex underlying mechanisms of RRB. This study piloted a multi-disciplinary approach to assess both the functional behavioral and neurophysiological factors that may underlie occurrences of RRB. The study (a) evaluated the effect of a modified functional analysis protocol on delineating functional subtypes of RRB and (b) explored the effect of using a wearable technology within a functional analysis on identifying the relationship between RRB and HRV.

Method

A single-case alternating treatment design was used to randomly alternate noncontingent low-stimulation and high-stimulation conditions in a modified functional analysis protocol. Simultaneous measurement of RRB and HRV was obtained through direct behavioral observations and a wristband that collects blood volume pulse, respectively. Visual analysis of time series data was used to determine the functional subtypes of RRB, and nonparametric correlational analyses were conducted to determine the association between HRV and RRB.

Results

Findings from a sample of six participants suggest preliminary effectiveness of the assessment protocol in identifying subtypes of RRB and a significant correlation between HRV and RRB.

Conclusions

This study demonstrates the potential effect and usability of a wearable technology-aided biobehavioral approach to assess RRB and HRV in individuals with ASD.

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.

Modern Biomarkers for Autism Spectrum Disorder: Future Directions

Autism spectrum disorder is an increasingly prevalent neurodevelopmental disorder in the world today, with an estimated 2% of the population being affected in the USA. A major complicating factor in diagnosing, treating, and understanding autism spectrum disorder is that defining the disorder is solely based on the observation of behavior. Thus, recent research has focused on identifying specific biological abnormalities in autism spectrum disorder that can provide clues to diagnosis and treatment. Biomarkers are an objective way to identify and measure biological abnormalities for diagnostic purposes as well as to measure changes resulting from treatment. This current opinion paper discusses the state of research of various biomarkers currently in development for autism spectrum disorder. The types of biomarkers identified include prenatal history, genetics, neurological including neuroimaging, neurophysiologic, and visual attention, metabolic including abnormalities in mitochondrial, folate, trans-methylation, and trans-sulfuration pathways, immune including autoantibodies and cytokine dysregulation, autonomic nervous system, and nutritional. Many of these biomarkers have promising preliminary evidence for prenatal and post-natal pre-symptomatic risk assessment, confirmation of diagnosis, subtyping, and treatment response. However, most biomarkers have not undergone validation studies and most studies do not investigate biomarkers with clinically relevant comparison groups. Although the field of biomarker research in autism spectrum disorder is promising, it appears that it is currently in the early stages of development.

Clinical Discordance in Monozygotic Twins With Autism Spectrum Disorder

There is a significant concordance of autism spectrum disorder in monozygotic (MZ) twins, where behavioral manifestations are heavily influenced by genetic factors. We describe a case of male monozygotic twins with autism spectrum disorder (ASD), raised in the same household, that present with different clinical manifestations. One of the twins presents with intermittent frank syncopal episodes, sinus bradycardia, and elevated alkaline phosphatase (ALP), while the other has symptoms of attention-deficit/hyperactivity disorder (ADHD), normal cardiological findings, and normal ALP level. The clinical discordance in this pair of monozygotic twins may be due to any of the following: 1) neuroanatomic cerebellar differences, 2) variable expression of genotype, and 3) inconsistent neurotransmitter regulation.

Cardiac Evaluation of Exercise Testing in a Contemporary Population of Preschool Children: A New Approach Providing Reference Values

The objective of this study was to evaluate cardiac autonomic function at rest, during maximal exercise, and in post-exercise recovery, to determine sex-specific and age-specific differences in resting heart rate (RHR), linear and spectral parameters of Heart Rate Variability (HRV), HR_peak, and heart rate recovery (HRR) after one and five minutes, in preschool children. This study involved a cohort of 167 healthy children (79 girls) aged 3 to 6 years that were selected from several schools in southern Spain. A 10 × 20 m test was conducted, and the cardiovascular response was recorded. No significant differences were found in all variables between the sexes. However, a significant reduction in RHR and an increase in HRR were found from age 4 to age 6. HRV parameters at rest were higher in older children. No associations between 10 × 20 m performance, weight status, and cardiac parameters were found. Simple linear regression analysis revealed that heart rate reserve (HRr), HRR_5min, RMSSD, and HF were the variables that showed association with all HR parameters. There was also a significant correlation between HRr and HRR_5min. In conclusion, cardiovascular autonomic function during rest, exercise, and recovery in Spanish preschool children was not influenced by sex, although older children showed greater cardiovascular modulation. Cardiorespiratory fitness status was not associated with HR response.

Attention to live eye contact in adolescents with autism spectrum disorder

A number of studies have reported diminished attention to the eyes in individuals with autism spectrum disorder (ASD). These studies predominantly used static images of faces as stimuli. Recent studies, however, have shown enhanced response to eye contact in typically developing (TD) individuals when they observe a person in a live interaction. We investigated physiological orienting to perceived eye contact in adolescents with ASD and TD adolescents when they observed a person in live interaction or viewed a photograph of the same person's face. We measured heart rate (HR) deceleration as an index of attentional orienting. Adolescents with ASD, as well as TD adolescents, showed significant HR deceleration for the direct gaze compared to an averted gaze in the live condition, but not in the photographic condition. The results suggest an intact response to perceived eye contact in individuals with ASD during a live face-to-face interaction. LAY SUMMARY: Individuals with autism spectrum disorder (ASD) have a different eye gaze pattern when observing photographic faces. However, little is known about how individuals with ASD process a real person's face. We measured heart rate (HR) and found that adolescents with ASD showed the typical decline in HR when they made eye contact with a real person, which suggests that both groups of individuals directed their attention to eye contact in a live face-to-face interaction.

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.

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.

Autonomic responses to facial expression tasks in children with autism spectrum disorders: Cross-section study

BACKGROUND

The autonomic nervous system has an influence on emotions and behavior modulation, however, the relationship between autonomic modulation impairment and the autism spectrum disorder (ASD) is yet to be fully described.

AIMS

To evaluate the autonomic responses of children with and without ASD through the non-linear, and linear heart rate variability (HRV) measures, and assess the correlation between these responses, the severity and behavioral symptoms of autism.

METHODS AND PROCEDURES

27 children diagnosed with ASD (EG = experimental group) and 28 matching controls (CG = control group) were evaluated. The HRV was evaluated in 15 min sections at the following moments: I) Resting condition; II) During facial expression tasks; and III) Recovery. The severity and behavioral symptoms of autism were evaluated by the Childhood Autism Rating Scale (CARS) and Autistic Behaviors Checklist (ABC) scales.

OUTCOMES AND RESULTS

The facial expression tasks influenced the activity of the autonomic nervous system in both groups, however the EG experienced more autonomic changes. These changes were mostly evidenced by the non-linear indices. Also, the CARS and ABC scales showed significant correlations with HRV indices.

CONCLUSIONS AND IMPLICATIONS

Children with ASD presented an autonomic modulation impairment, mostly identified by the non-linear indices of HRV. Also, this autonomic impairment is associated with the severity and behavioral symptoms of autism.

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.

Equivalent Behavioral Facilitation to Tactile Cues in Children with Autism Spectrum Disorder

The alerting network, a subcomponent of attention, enables humans to respond to novel information. Children with ASD have shown equivalent alerting in response to visual and/or auditory stimuli compared to typically developing (TD) children. However, it is unclear whether children with ASD and TD show equivalent alerting to tactile stimuli. We examined (1) whether tactile cues affect accuracy and reaction times in children with ASD and TD, (2) whether the duration between touch-cues and auditory targets impacts performance, and (3) whether behavioral responses in the tactile cueing task are associated with ASD symptomatology. Six- to 12-year-olds with ASD and TD participated in a tactile-cueing task and were instructed to respond with a button press to a target sound /a/. Tactile cues were presented at 200, 400, and 800 ms (25% each) prior to the auditory target. The remaining trials (25%) were presented without tactile cues. Findings suggested that both groups showed equivalent alerting responses to tactile cues. Additionally, all children were faster to respond to auditory targets at longer cue–target intervals. Finally, there was an association between rate of facilitation and RRB scores in all children, suggesting that patterns of responding to transient phasic cues may be related to ASD symptomatology.

Social-Pragmatic Inferencing, Visual Social Attention and Physiological Reactivity to Complex Social Scenes in Autistic Young Adults

This study examined social-pragmatic inferencing, visual social attention and physiological reactivity to complex social scenes. Participants were autistic young adults (n = 14) and a control group of young adults (n = 14) without intellectual disability. Results indicate between-group differences in social-pragmatic inferencing, moment-level social attention and heart rate variability (HRV) reactivity. A key finding suggests associations between increased moment-level social attention to facial emotion expressions, better social-pragmatic inferencing and greater HRV suppression in autistic young adults. Supporting previous research, better social-pragmatic inferencing was found associated with less autistic traits.

Polychlorinated Biphenyls (PCBs): Risk Factors for Autism Spectrum Disorder?

Autism spectrum disorder (ASD) includes a group of multifactorial neurodevelopmental disorders defined clinically by core deficits in social reciprocity and communication, restrictive interests and repetitive behaviors. ASD affects one in 54 children in the United States, one in 89 children in Europe, and one in 277 children in Asia, with an estimated worldwide prevalence of 1-2%. While there is increasing consensus that ASD results from complex gene x environment interactions, the identity of specific environmental risk factors and the mechanisms by which environmental and genetic factors interact to determine individual risk remain critical gaps in our understanding of ASD etiology. Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been linked to altered neurodevelopment in humans. Preclinical studies demonstrate that PCBs modulate signaling pathways implicated in ASD and phenocopy the effects of ASD risk genes on critical morphometric determinants of neuronal connectivity, such as dendritic arborization. Here, we review human and experimental evidence identifying PCBs as potential risk factors for ASD and discuss the potential for PCBs to influence not only core symptoms of ASD, but also comorbidities commonly associated with ASD, via effects on the central and peripheral nervous systems, and/or peripheral target tissues, using bladder dysfunction as an example. We also discuss critical data gaps in the literature implicating PCBs as ASD risk factors. Unlike genetic factors, which are currently irreversible, environmental factors are modifiable risks. Therefore, data confirming PCBs as risk factors for ASD may suggest rational approaches for the primary prevention of ASD in genetically susceptible individuals.