Heart Activity during Startle Paradym in Children with Fragile X Syndrome and Autism Spectrum Disorder Compared to Typically Developing Children

Poster Presentation
Thursday, May 10, 2018: 5:30 PM-7:00 PM
Hall Grote Zaal (de Doelen ICC Rotterdam)
J. A. Ezell1, E. A. Will2, S. McQuillin1 and J. E. Roberts2, (1)University of South Carolina, Columbia, SC, (2)Psychology, University of South Carolina, Columbia, SC
Background: Fragile X syndrome (FXS) is a monogenetic disorder characterized by abnormal social behavior and intellectual disability. FXS is also the most frequent known heritable genetic cause of autism spectrum disorder (ASD), which makes it an ideal model for studying ASD. High rates of anxiety have been reported in both FXS and ASD with features of anxiety overlapping with ASD symptomatology in both clinical groups. Capturing anxiety in young children with FXS or ASD is challenging as verbal deficits can limit self-report and most measures are normed for older children or adults in these populations (Spence et al 2001). Behavioral and physiological measures of anxiety can provide important insight into early features of anxiety in children with FXS or ASD. Elevated heart rate and reduced modulation in response to threat can be indicative of anxiety (Whalen et al, 2017). Physiological reactivity to an auditory startle captures reflexive responses linked to underlying physiological mechanisms associated with anxiety. Given that children with FXS and ASD demonstrate dysregulated autonomic activity and related challenges modulating heart activity compared to typically developing (TD) children (Klusek et al, 2015; Roberts et al, 2012), heart activity in auditory startle response can provide insight into anxiety features in these high-risk groups.

Objectives: The purpose of this study is to characterize heart activity in response to an auditory startle in children with FXS and in children with ASD contrasted to low-risk controls. We predict that children with FXS or ASD will react with elevated heart activity to the auditory startle task compared to TD children.

Methods: Participants included 25 children with FXS, 21 TD children, and 11 children with idiopathic ASD (n =20 by INSAR) between the ages of 3-6 years old who are participating in an ongoing study. The auditory startle task takes place in the context of a silent children’s movie and is comprised of a three phases, 1). The pre-startle (30 seconds), 2) startle (1 second), and 3) post-startle (60 seconds).

Results: We examined patterns in heart activity during auditory startle response across FXS, ASD, and TD groups using a multi-level model, wherein 1s epochs were nested within children. The FXS and TD groups differed in startle response heart activity B=.50(.19), t=2.51, however, FXS and ASD groups did not B=.27(.19),t=1.39. Model results indicate that the FXS and ASD groups showed increased startle response heart rate, whereas the TD group showed a decrease (see figures).

Conclusions: These preliminary findings are consistent with previous research showing altered physiological reactivity in clinical samples with FXS and ASD compared to TD children. Results suggest that autonomic reactivity, indexed by heart rate, may represent a shared mechanistic vulnerability with anxiety in FXS and ASD. Elevated heart rate following startle response might be an early feature of anxiety in young children with FXS or ASD. Behavioral data are being coded during the startle experiment, and these data will be integrated with heart activity for presentation at the conference.