Evaluating Balance and Gaze in Young Adults with Autism Spectrum Disorder During an Immersive Virtual Reality Perturbation

Abstract

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder impacting 1 in 31 individuals in the United States characterized by communication deficits and restricted, repetitive behavior. Individuals with ASD have been known to display a distinct balance mechanism in comparison to typically developing (TD) peers, resulting in the potential for an elevated fall risk. This may be explained by sensorimotor integration differences associated with the disorder including the acquisition and implementation of visual information. Much of the existing literature fails to address a young adult population and include the components of oculomotor behavior and balance combined in immersive environments, thus, the purpose of this study was to determine how young adults with ASD respond before, during, and after an immersive virtual reality perturbation. Twenty young adults diagnosed with ASD (25.6  4.59 years) and 20 TD individuals (21.15  2.76 years) were recruited for this study. On day one, participants completed a 30-second quiet standing (QST) baseline balance trial, a 120-second virtual reality perturbation (MCR) trial equipped with an oculomotor task, and a 90-second recovery (REC) trial immediately following VR exposure. On day two, participants completed a 120-second static virtual reality (VRB) trial. Balance data was collected using an embedded force plate for all trials, and eye tracking data was collected for the visual task employed in MCR trials. To make data segments easily comparable, MCR and VRB trials were divided into 30-second epochs for MCR 1-3 and VRB 1-3. Analysis 1 employed 2 x 7, Group x Condition mixed ANOVAs to explore general differences in postural control by condition. Analysis 2 employed bivariate correlations between postural control and oculomotor variables during MCR trials and independent samples t-tests to determine group differences in oculomotor variables. Analysis 3 employed 2 x 2, Group x Condition ANOVAs to examine postural control differences during perturbation and static VR conditions. Analysis 1 revealed significant (p < 0.05) between-subjects effects for 95% confidence ellipse area and center of pressure (COP) path length, significant within-subjects effects for COP velocity in the anteroposterior (y) direction, COP acceleration in the mediolateral (x) and y- directions, COP approximate entropy in the x- and y- directions, COP displacement in the y- direction, virtual time to contact (VTC) and minimum VTC (min-VTC), and significant a significant interaction effect for minVTC. Analysis 2 yielded no significant correlation between any oculomotor and postural control variable for any MCR epoch but revealed significant group differences for mean score and mean score accuracy during the oculomotor task. Analysis 3 revealed significant group differences (ASD > TD) for COP x- and y-velocity/displacement, 95% confidence ellipse area, and COP path length in addition to significant within-subjects effects (VRB > MCR) for y-velocity/displacement, x- and y- COP approximate entropy, COP path length, VTC, and minVTC. Findings regarding group differences are congruent with existing literature concerning elevated sway and general alternative postural control mechanisms observed in ASD populations. Differences observed between groups in oculomotor behavior may be attributed to saccadic behavior discrepancies in ASD, which may reflect a substandard allocation of attentional resources in this population. Such processes may partially explain differences observed in postural control between static and dynamic VR environments, along with intricacies reweighing sensory information during the maintenance of balance in dual- and single-task environments. Overall, our findings highlight the need for further concurrent exploration of visual and postural control behavior in individuals with ASD in a variety of immersive and non-immersive environments to aid in creating therapeutic protocols that directly target differences.