A Behavioral-Physiological Approach to Characterizing Emotion in Infants at Risk for Autism Spectrum Disorder
Objectives: The objectives of this study were to determine (1) the relation between behavioral affect and heart-rate during an emotion regulation task, and (2) whether behavioral affect and/or heart-rate predict ASD symptom expression in a high-risk (HR) infant sibling cohort.
Methods: Participants: Participants, drawn from an ongoing longitudinal study of early development of ASD, were 35 HR infants with an older sibling with ASD. Infants were assessed at 12 months of age. Emotion Regulation: The emotion regulation task, adapted from the Laboratory Temperament Assessment Battery, is comprised of activities designed to elicit positive (bubbles, toy play) and negative (toy removal, masks, grooming) emotions (Goldsmith et al., 1996). Infant behavioral affect was coded using Noldus Observer software. Affect was coded for valence (positive, negative, or neutral) and intensity (to differentiate mild/moderate displays from intense displays of affect). Raw heart-rate was recorded and extracted from an electrocardiogram signal using Thought Technologies Procom5 Infiniti. The data were processed and transformed into a metric of average change in heart-rate from baseline. ASD Symptom Expression: The Autism Observation Scale for Infants (AOSI; Bryson et al., 2007), a clinician-led observational assessment, was used to measure early signs of ASD. Analytical Approach: Average values were calculated for behavioral affect and heart-rate across 5-second time bins. Data were analyzed using a series of Spearman rank-order correlations to determine the (1) relation/congruence between behavioral affect and heart-rate, and (2) relation between affect intensity and heart-rate with AOSI total score.
Results: A significant correlation between behavioral affect and heart-rate was found for the grooming activity (rs=-0.458, p=0.003), but not other emotion-eliciting activities (p’s>0.05; Table 1). Behavioral affect was significantly correlated with AOSI total score for bubbles (rs=-0.692, p<0.001), toy play (rs=-0.337, p=0.026), and grooming activities (rs=-0.337, p<0.026). No significant correlations were observed between heart-rate and AOSI total score on any emotion-eliciting activities (Table 2).
Conclusions: The results suggest modest congruence between behavioral affect and heart-rate indices of emotion regulation in 12-month-old HR infants. Behavioral affect during the positive and negative emotion-eliciting activities was correlated with concurrent ASD symptom expression in HR infants, whereas heart-rate was not. Further work is warranted on modeling physiological responses to tasks eliciting various emotions in HR infants. Using this approach, we may be able to discern behavioral and physiological differences between infants who are diagnosed with ASD from those who are not.