Baseline Autonomic State Predictive of Social Responsiveness in Children with Autism Spectrum Disorders

Background: As noted in the diagnostic criteria of the Diagnostic and Statistical Manual for Mental Disorders-4th Edition (DSM-IV; American Psychiatric Association, 2000), children with Autism Spectrum Disorders (ASD) struggle with social interactions, including eye contact, vocalizations, and facial affect. Spurred by the minimal effects of social skill interventions (Bellini, Peters, Benner, & Hopf, 2007), the present study diverges from the common understanding of social skill deficits and introduces an autonomic nervous system circuit that may be one root of social problems. The Polyvagal Theory (e.g., Porges, 2005, 2007, 2008) outlines a Social Engagement System that consists of interconnected cranial nerves. According to the Polyvagal Theory and the Social Engagement System, social dysfunction as seen in ASD should be paired with physiological dysfunction (i.e., fight-flight state). Research finds children with ASD show a fight-flight state (i.e., high heart rate and low heart rate variability) to unfamiliar individuals and during baseline when compared to typically developing children (Ming, Julu, Brimacombe, Connor, & Daniels, 2005). Prior research has not indicated that physiological dysfunction is predictive of social dysfunction in children with ASD.

Objectives: We hypothesize that baseline autonomic state (i.e., heart rate and heart rate variability) is predictive of parent-reported social responsiveness in children with ASD. Specifically, a higher baseline heart rate (HR) should predict lower parent-reported social responsiveness, and lower baseline heart rate variability (HRV) should predict lower parent-reported social responsiveness.

Methods: Preliminary data analyses were conducted on eighteen children, aged 4-7, previously diagnosed with an ASD. Participants were administered a 3-minute baseline video while cardiac and respiratory measures were recorded with a LifeShirt®. During this time, the child's guardian completed the Social Responsiveness Scale (SRS; Constantino, 2002). The SRS measures: social awareness, social cognition, social communication, social motivation, and autistic mannerisms.

Results: Initial analyses showed that baseline HR significantly predicted total SRS score, β = .46, t(16) = 2.09, p < .05, with higher HR related to increased social dysfunction. Furthermore, baseline HRV (i.e., high frequency normalized units) significantly predicted total SRS score, β = -.45, t(15) = -1.97, p < .05, with reduced HRV related to increased social dysfunction. One-tailed correlations for SRS subscales indicated that 1) increased baseline HR was associated with more dysfunction in social motivation, r(16) = .46, p = .03, autistic mannerisms, r(16) = .35, p = .075, and social cognition, r(16) = .33, p = .089, and 2) decreased baseline HRV was associated with more dysfunction in social cognition, r(15) = -.33, p = .098, and autistic mannerisms, r(15) = -.39, p = .062.

Conclusions: Initial results supported our hypotheses that higher baseline HR and reduced HRV were related to dysfunctional social responsiveness, particularly social motivation, cognition, and mannerisms. Our results support the tenants of the Polyvagal Theory and the Social Engagement System, suggesting that physiological dysfunction is reflective of an overactive fight-flight state that may increase the likelihood of social difficulties in the child. Future studies should identify strategies to calm this over aroused state to potentially improve social responsiveness.