Postural and Cortical Responses Following Visual Occlusion in Adults With and Without ASD

Attention and sensory integration for gait in young adults with autism spectrum disorder

INTRODUCTION

Altered sensorimotor function is a common feature of autism spectrum disorder (ASD). As a result, spatiotemporal walking patterns are typically affected. Attentional processes relevant for locomotion may be altered in people with ASD. This study assessed the extent to which gait alterations observed under sensory challenging conditions are due to reduced attention-related processes in young adults with ASD.

METHODS

Twenty-one adults with ASD and 21 age- and sex-matched neurotypical participants walked at a self-selected pace on a 10-m walkway under 12 sensory/attention conditions: hard or carpet flooring; well-lit or dim lighting; no attention task, an auditory choice-reaction time information-processing task, or a simple reaction time information-processing task. Gait data were collected with a 12-marker motion capture set and a trunk accelerometer. Spatiotemporal characteristics of gait were derived and compared between the two groups across gait conditions.

RESULTS

Floor/light conditions impacted gait speed, average step length, average stance time, average step width, and step width variability similarly in both groups (p<0.05). The information processing tasks impacted average step length, gait speed, and step length variability (p<0.05). Group differences were found in step length metrics: the ASD group had decreased average step length during the simple reaction time information-processing task and neurotypical participants did not (p=0.039); the ASD group had increased variability on carpet compared to hard floor and the neurotypical group had no change in variability due to floor (p=0.015).

SIGNIFICANCE

These results suggest that attentional set-shifting and somatosensory inputs may play an important role in ASD-related gait alterations. Step length metrics appear to be sensitive to group differences between ASD and neurotypical adults during sensory challenging conditions.

Community-based postural control assessment in autistic individuals indicates a similar but delayed trajectory compared to neurotypical individuals

Autistic individuals exhibit significant sensorimotor differences. Postural stability and control are foundational motor skills for successfully performing many activities of daily living. In neurotypical development, postural stability and control develop throughout childhood and adolescence. In autistic development, previous studies have focused primarily on individual age groups (e.g., childhood, adolescence, adulthood) or only controlled for age using age-matching. Here, we examined the age trajectories of postural stability and control in autism from childhood through adolescents using standardized clinical assessments. In study 1, we tested the postural stability of autistic (n = 27) and neurotypical (n = 41) children, adolescents, and young adults aged 7-20 years during quiet standing on a force plate in three visual conditions: eyes open (EO), eyes closed (EC), and eyes open with the head in a translucent dome (Dome). Postural sway variability decreased as age increased for both groups, but autistic participants showed greater variability than neurotypical participants across age. In study 2, we tested autistic (n = 21) and neurotypical (n = 32) children and adolescents aged 7-16 years during a dynamic postural control task with nine targets. Postural control efficiency increased as age increased for both groups, but autistic participants were less efficient compared to neurotypical participants across age. Together, these results indicate that autistic individuals have a similar age trajectory for postural stability and control compared to neurotypical individuals, but have lower postural stability and control overall.

Attention and sensory integration for postural control in young adults with autism spectrum disorders

Postural control impairments have been reported in adults with autism spectrum disorders (ASD). Balance relies on the integration of multisensory cues, a process that requires attention. The purpose of this study was to determine if the influence of attention demands on sensory integration abilities relevant for balance partially contributes to postural control impairments in ASD. Young adults with ASD (N = 24) and neurotypical participants (N = 24) were exposed to sensory perturbations during standing. An established dual-task paradigm was used, requiring participants to maintain balance in these sensory challenging environments and to perform auditory information processing tasks (simple reaction time task and choice reaction time task). Balance was assessed using sway magnitude and sway speed, and attention demands were evaluated based on the response time in the auditory tasks. While young adults with ASD were able to maintain balance in destabilizing sensory conditions, they were more challenged (greater sway speed) than their neurotypical counterparts. Additionally, when exposed for an extended amount of time (3 min) to the most challenging sensory condition included in this study, adults with ASD exhibited a reduced ability to adapt their postural control strategies (sway speed was minimally reduced), demonstrating a postural inflexibility pattern in ASD compared to neurotypical counterparts. Finally, the impact of performing an auditory information processing task on balance and the dual-task cost on information processing (response time) was similar in both groups. ASD may disrupt temporal adaptive postural control processes associated with sensory reweighting that occurs in neurotypicals.