Perceiving Pain in Others: Altered Physiological and Cognitive Regulation of Distress in ASD

Background:  Perceiving the pain of others normally activates the affective brain areas responsible for perceiving self-pain. These responses are thought to be required for feeling empathic concern for others, but need to be down-regulated in order to minimise personal distress and facilitate prosocial behaviour. Evidence from neuro-imaging studies suggest that vicarious responses are poorly regulated in autism spectrum disorder (ASD), but corresponding electrophysiological evidence is scant. Furthermore, there is evidence that poor self-regulation may stem in part from deficits in perspective-taking and own-emotion understanding (alexithymia).

Objectives: We investigated affective and sensory-motor empathy in individuals with varying levels of autism traits in response to viewing sensory pain displays. We also investigated the relationship of perspective-taking ability and alexithymia to self-reported personal distress and empathic concern. We hypothesised that participants with higher autism traits would show (1) poorer perspective-taking and higher levels of alexithymia, and (2) greater muscle activation, distress and sympathetic arousal when observing pain.

Methods: 105 individuals (27 ASD; ages 14 – 46) completed the Toronto Alexithymia Scale (TAS-20), the Interpersonal Reactivity Index (distress and empathic concern indices) and the Emotional Contagion Scale. Autism trait scores were calculated using participants' Autism Diagnostic Observation Schedule 2 algorithm and Autism Spectrum Quotient scores. Participants were shown videos of painful stimuli (a hand being stabbed), during which muscle activity in the participant's hand was measured at 100ms intervals using surface electromyography. Skin conductance responses were sampled as a measure of sympathetic activity. Using multilevel modelling, autism traits were correlated with (1) self-reported trait empathic concern, personal distress, emotional contagion and alexithymia, and (2) muscle activation and skin conductance when observing pain.

Results: High levels of alexithymia (p = .0006) and emotional contagion (p < .0001), and higher autism traits (p = .038), predicted higher personal distress.  In contrast, good perspective-taking (p < .0001), low alexithymia (p = .0002) and high emotional contagion scores (p < .0001) predicted higher levels of empathic concern. Autism trait scores did not predict empathic concern (p = .550). Participants with high levels of autism traits had significantly higher muscle activity; with the highest activity occurring at the time of highest pain intensity in the video (p = .0043). Skin conductance was significantly higher in participants with high autism traits and those with high trait levels of distress (p = .0064).

Conclusions: The study replicates and extends previous findings showing that people with ASD experience increased levels of distress and physiological arousal when witnessing painful stimuli. Alexithymia and poor perspective-taking in this group may contribute to the distress experienced. Physiologically, participants with high autism traits had significantly greater sympathetic arousal and muscle activation than those with low autism traits and low trait levels of distress. Autism trait levels were not correlated with empathic concern. These findings suggest intact empathic concern in ASD, but poorer self-regulation of vicarious emotion at the cognitive and physiological levels. Our data speak to the potential value of incorporating self-regulation strategies into ASD interventions to reduce distress and promote prosocial behaviour.