Autonomic Nervous System Function in Response to Social Judgment in Adolescents with and without Autism Spectrum Disorder

Background:  Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by deficits in reciprocal social behavior. However, it is unclear if deficits in social behavior are primarily due to disinterest in social stimuli, or to elevated stress response to social information or events. The autonomic nervous system helps to facilitate salience detection, approach, and avoidance behavior in response to sensory information, including social stimuli. Research in our lab has shown enhanced responsivity to social stress and variable biobehavioral profiles in children with ASD. Previous work with children with ASD has also demonstrated alterations in autonomic regulation, including respiratory sinus arrhythmia (RSA), a measure of vagal control over heart rate fluctuation. The majority of prior work has focused on children with ASD, but adolescents with ASD have been understudied. The adolescent period may be of particular interest to the study of ASD, as this developmental epoch is associated with increased salience of social judgment in typically developing (TD) populations.

Objectives: In this study, we employed the Trier Social Stress Test (TSST) to study RSA response to social judgment in ASD compared to TD adolescents.  

Methods: Participants with ASD or TD ages 12-17 underwent a modified version of the TSST as part of a larger study of stress and social behavior. In this modified version, one of the raters was replaced with an age-matched peer. At arrival and during the TSST, vagal tone and cardiac output were measured using MindWare, a mobile unit that measures real-time cardiac and respiration data. The TSST included four 5-minute periods: preparation, speech, mental subtraction, and debriefing. Heart rate data was cleaned and RSA was calculated using the MindWare software suite. RSA data was log-transformed to correct for skewness of the data. We performed repeated measures ANOVA to determine group differences in RSA at baseline and during each 5-minute portion of the TSST. We included pubertal status, as assessed by the Physical Development Scale, as a covariate in our model. Additional post hoc t-tests were performed to assess for group differences at each time point.    

Results: There was a significant effect of diagnosis on RSA values (p=0.03), with post hoc analyses suggesting significant differences in RSA between groups during the speech (p=0.027), mental subtraction (p=0.001), and debriefing (p=0.013) portions of the task. TD participants showed higher mean RSA values than ASD participants, with no significant differences in baseline RSA. There were no significant effects of pubertal status or interaction effects with diagnosis. 

Conclusions: Our findings indicated differences in autonomic arousal in ASD adolescents compared to TD peers. TD peers overall showed elevated RSA during the TSST compared to baseline RSA, suggesting engagement of the ANS in preparation for the stress challenge. Meanwhile, the ASD group overall did not show such engagement of the ANS, and in fact showed a significantly decreased RSA compared to baseline, suggesting a poorly regulated vagal tone. These findings suggest that autonomic dysregulation may contribute to social behavior deficits in ASD.