Examining Tactile Sensitivity and Associations with Physiological Arousal and Social Functioning in Youth with Autism Spectrum Disorder.

Background: Autism spectrum disorder (ASD) is characterized by significant difficulties in social cognition and communication, as well as impairments in sensory processing. Previous findings have consistently shown elevated evening cortisol in youth with ASD compared to typically developing (TD) peers (Tomarken et al., 2015), suggesting increased accumulation of stress throughout the day (Corbett et al., 2009). Various factors may underlie this increased arousal, to include significant stress from social interaction, changes throughout the days, or heightened sensory sensitivity to internal or external stimuli.

Objectives: The current study examined potential associations between sensory processing, physiological arousal, and social responsiveness in ASD. It was hypothesized that underlying sensory defensiveness would be associated with increased arousal and reduced social functioning in youth ASD.

Methods: A large sample (N=113) of youth with ASD (N=64) or TD (N=49) between 8 and 17 years of age were recruited. Evening cortisol was collected as part of a larger study, which collected diurnal salivary samples over 3 days at home, 4 times per day (Immediate Waking, 30-min post-waking, afternoon, and evening). Sensory sensitivity was reported using the Short Sensory Profile (SSP). Social functioning was assessed by three parent-report measures including the Social Communication Questionnaire (SCQ), Social Responsiveness Scale (SRS), and the Child Behavior Checklist (CBCL). Pearson product correlations were conducted to measure levels of association between dependent variables.

Results: Sensory functioning (SSP) was negatively correlated with evening cortisol at trend-level (r=-.18, p=0.08). When individual subscales of the SSP were explored, a significant negative correlation was observed for the Tactile domain and evening cortisol (r=-.28, p=0.007). Moreover, the SSP Tactile domain was also negatively associated with measures of social functioning, including the SCQ (r=-.64, p<0.001), the SRS total score (r=-.69, p<0.001), and the social problems subscale on the CBCL (r=-.69, p<0.001). Within group comparison for the ASD group, corroborated relationships between tactile sensitivity and physiological and social functioning: SSP Tactile showed negative associations with evening cortisol (r=-.31, p=0.03), SCQ (r=-.33, p=0.02), SRS (r=-.43, p<0.001), and social problems on the CBCL (r=-.61, p<0.001). In the TD group, tactile sensitivity was only correlated with total SRS (r=-.36, p=0.01).

Conclusions: The study reveals significant associations between evening cortisol, sensory processing, and social functioning. Tactile sensitivity was related to physiological regulation and social responsiveness, such that impaired tactile processing corresponded with elevated evening cortisol and greater impairment in social functioning. Findings suggest sensory processing, especially tactile defensiveness, may underlie a number of symptoms in ASD, including accumulated stress, social responsiveness, and social symptom severity. The lack of significant findings in the TD group further suggest this underlying role of sensory processing may be unique to ASD. Tactile responsiveness may serve as a marker of more significant impairment in other core symptom domains, and future research should be directed towards understanding the directionality of these relationships, such that treating one symptom may directly or indirectly improve the others.