Tonnsen, B., Richards, J.E., & Roberts, J.E. (2018). Heart Rate-Defined Sustained Attention in Infants at Risk for Autism. Journal of Neurodevelopmental Disorders.
Background: Although aberrant visual attention has been identified in infants at high familial risk for autism, the onset and mechanisms these profiles remain unclear. Integrating biomarkers of attention into prospective high-risk infant studies may inform more nuanced developmental trajectories, clarifying the onset and course of atypical attention and potentially advancing early screening or treatment protocols. Heart rate-defined sustained attention (HDSA) is a well-validated biomarker of attentional engagement that, in non-clinical infant populations, provides incremental information about attentional engagement beyond looking behaviors alone. The present study aimed to examine the characteristics and clinical correlates of HDSA in high-risk infants, informing whether HDSA may operate as a promising biomarker of attention and clinical symptoms in this population. Methods: We examined age-related patterns of HDSA during a passive looking task in 5-14 month old high-risk infant siblings of children with autism (n=21) compared to low risk controls (n=21), with most participants contributing multiple assessments. Emergent autism features were measured using the Autism Diagnostic Observation Schedule at 24 months. Primary dependent variables included the proportion of time in behavioral attention, proportion of time in HDSA, and average heart rate deceleration during HDSA. For each variable, we used nested multilevel models to examine whether attention differed by group, as well as whether attention predicted emergent autism features among HR infants. Results: As expected, HDSA served as a global biomarker of attention in high-risk infants, predicting greater variability in group risk status than behavioral looking alone. Among high-risk infants, more severe ASD features were also associated with increasingly shallow HDSA decelerations across development, suggesting abnormal qualities of HDSA may inform individual differences within this population. Conclusions: These preliminary findings provide initial evidence that HDSA may offer a sensitive, affordable, and portable biomarker of attention that may enhance understanding of atypical attention in high-risk infants. Using this method, we also provide initial evidence that atypical patterns of heart activity previously reported in children and adults with autism may emerge in the first year of life, warranting further study of how HDSA may specifically inform attention profiles in ASD.