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

Abstract

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.

Autonomic and hedonic response to affective touch in autism spectrum disorder

“…While recent studies have delved into understanding the physiological responses associated with affective touch in neurotypical individuals (Chatel-Goldman et al, 2014;Mazza et al, 2023;Triscoli et al, 2017), the only study that has focused on autonomic responses to affective touch in children with ASD has reported an overall hypoactivation in ASD children compared to TD peers (Bufo et al, 2022). Bufo et al (2022) have proposed that the diminished autonomic activation observed in ASD children when receiving affective touch could be attributed to a reduced engagement reaction commonly found in the ASD population. This reaction is likely influenced by both a lack of social motivation (Chevallier et al, 2012), and a deficiency in rewarding experiences associated with touch in general (Gordon et al, 2016) typical of the ASD subjects.…”

“…This reaction is likely influenced by both a lack of social motivation (Chevallier et al, 2012), and a deficiency in rewarding experiences associated with touch in general (Gordon et al, 2016) typical of the ASD subjects. However, in their pioneering work Bufo et al (2022) did not contrast the physiological response to affective touch with any other type of control touch. In contrast, our experiment uncovered this critical point by showing that while autonomic responses to affective touch were greater than those to control touch in TD individuals, participants with ASD exhibited comparable levels of activation between the two types of touch.…”

“…Recent research has started to examine in TD individuals autonomic nervous system responses-pupil dilation, skin conductance, and heart rate activity-evoked by affective touch (Chatel-Goldman et al, 2014;Gusso et al, 2021;Mazza et al, 2023;Triscoli et al, 2017) but to our knowledge only one study has investigated physiological responses to affective touch within the ASD population and has reported an overall hypoactivation in children with ASD compared to TD children (Bufo et al, 2022). Nevertheless, the limited research on autonomic responses to affective touch in adults with ASD, coupled with the observed dissociation between explicit and implicit outcomes in this population-present in other sensory domains (Mazza et al, 2020) -underscores the necessity for additional investigations.…”

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

“… 83 Future research on interoception at early processing levels, such as the function of peripheral small fibers and the relation to the autonomic regulation, could also contribute to the understanding of some behavioral and social symptomatology experienced by autistic individuals. 107 , 140 …”

“…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.…”