Analysis of Motor Behavior based on Recurrence Analysis in Adults with Autism Spectrum and Neurotypicals in a Dynamic Balance Task: a pilot study

Abstract

Introduction: Autism spectrum disorders (ASD) refers to a range of neurodevelopmental disorders with deficits in postural control (PC), motor development and coordination. The PC deficit appears to be persistent across the spectrum and can limit the acquisition of new motor skills with severe consequences in life's' quality. Objectives: i) to verify if the nonlinear techniques can identify the local recurrence pattern in the phase space of the PC, in individuals with ASD, ii) to compare the PC between ASD and neurotypical individuals, during a task of dynamic rotation balance. Methods: six male adult individuals, three autistic and three neurotypicals, performed a dynamic balance task, where angular velocity data was collected from the trunk. Results: Despite the inexistence of significant differences, autistic adults revealed, for all planes of movement, higher mean values of recurrence, periodicity, stability (except for the maximum line in the transversal plane), complexity and intermittence; differences that were visually confirmed by observing the recurrence graphs. Autistic participants also revealing lower mean values of Lyapunov exponent, meaning less divergency and variability than the neurotypicals. Conclusions: the autistic's postural control strategy of a greater periodicity, stability and a lower divergence and variability, may result from less plasticity in the ability to adjust to momentary states of postural imbalance. This strategy could be linked to the autistic's stereotypical behavior of continuously cyclical movements. However, this does not result in greater variability in movement, but less variability. Given the neuro-motor difficulty of these autistic adults in producing varied ranges of motion, it is recommended to introduce dynamic balance activities, starting with reduced levels of postural stability disturbance.