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

Abstract

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.

Interoception in Autism: A Narrative Review of Behavioral and Neurobiological Data

“…A recent meta-analysis investigated the physiological response in autistic individuals in comparison to a non-autistic group, focusing on two key factors: (a) the type of physiological measure used, particularly its connection to the autonomic nervous system branches (sympathetic and parasympathetic); and (b) the social context in which the measurements were taken. 106 The findings revealed significant differences between groups, particularly in relation to the activity of the parasympathetic nervous system and the combined activity of the sympathetic and parasympathetic systems during social interactions. Specifically, respiratory sinus arrhythmia, a common measure of peripheral nervous system activity, showed reduced activity during exposure to environmental stimuli.…”

“…This may suggest that in autism, there may be differences in inhibitory mechanisms needed to reallocate physiological resources in response to external factors. 106 Along this line, in both autistic and non-autistic children, Bufo et al 107 collected autonomic parameters during gentle tactile stimulation in two skin regions, one corresponding to high-intensity C fibers (forearm), and the other to low-intensity C fibers l (palm of the hand). In response to tactile stimuli on both skin regions, non-autistic children had an increase in pupil diameter and skin conductance, along with a decrease in heart rate.…”