Examining Patterns of Physiological Arousal in Children with and without Autism Spectrum Disorder

Background: Autism Spectrum Disorder (ASD) is characterized by impairments in social communication and restricted and repetitive behaviors (American Psychiatric Association [APA], 2013). Cardiovascular activity has been studied as a biomarker for social-emotional functioning (Beauchaine, 2015; Patriquin et al., 2014) with increased autonomic dysregulation being associated with more social and emotional problems (Shahrestani et al., 2014). One common metric of autonomic activity is heart rate variability (HRV), or the fluctuation in the time interval between heartbeats. Respiratory sinus arrhythmia (RSA) is a measure of HRV that is associated with parasympathetic activity or the restoration of physiological functioning when the body is at rest (Porges, 1995). In typically developing populations, higher levels of RSA are related to better social functioning (Patriquin et al., 2014). However, these relationships are not well characterized in younger children with ASD.

Objectives: The present study aims to examine the relationships of physiological measures of arousal and ASD symptomology in preschool-aged children with and without a diagnosis of ASD during conditions with varying social demands.

Methods: Preliminary data were collected from 20 children between the ages of 2-5 years that participated in an ongoing study examining physiological arousal and symptoms of ASD and anxiety in preschoolers with and without ASD. Participants were categorized into two groups: children with a clinical diagnoses of ASD (N=11) and typically developing children (N=9). Physiological data included average heart rate (HR) and RSA collected during the following conditions: (1) baseline, (2) play-based assessment (Autism Diagnostic Observation Schedule; ADOS-2), and (3) recovery. The participants viewed a video for 5 minutes during the baseline and recovery conditions. The ADOS-2 severity score was used as a measure of ASD symptoms.

Results: Preliminary results indicate that children with ASD demonstrated lower levels of baseline RSA (M = 6.22) and recovery RSA (M = 6.02) than typically developing children (M = 6.61 and M= 6.79 respectively). Additionally, typically developing children displayed higher levels of RSA during the play-based condition (M = 6.93) than children with ASD (M = 6.09). Levels of RSA increased during the play-based condition in typically developing children, whereas levels of RSA decreased in the play-based condition in children with ASD. Children with ASD had higher measures of HR across baseline (M = 115.70), play-based (M= 117.40), and recovery (M= 111.54) conditions compared to the typically developing group across respective conditions (M=113.18, M= 114.16, and M =108.55). Autism symptom severity was negatively related to RSA in the baseline (r = -.561), play-based (r =-.227), and recovery (r =.608) conditions in the ASD group.

Conclusions: It is critical to identify potential subgroups in young children that may confer increased risk given specific biological and behavioral profiles. These preliminary findings suggest differences in patterns arousal across conditions with varying social demands in children with and without ASD. Results suggest that ASD symptom severity is related to parasympathetic influence and regulation. The detection of physiological processes that are associated with symptom presentation will allow for future studies to examine potential mechanistic factors that can be targeted for intervention.