The interplay between cognitive tasks and vision for upright posture balance in adolescents

The influence of cognitive load and vision variability on postural balance in adolescents with intellectual disabilities

Introduction

This study aimed to investigate the impact of cognitive load, particularly its escalation during the execution of the same test, under varying vision conditions, on postural balance among adolescents with intellectual disability (ID).

Methods

Twenty adolescents underwent balance assessments under different visual conditions (Open Eyes (OE), Closed Eyes (CE), Flash, Goggles, Visual Stimulation (VS)) and task settings (Single Task (ST), Dual Task (DT) without challenges, and DT with challenges). The cognitive test was assessed using Verbal Fluency (VF).

Results and discussion

Significant effects were found for Task (p < 0.001, ηp2 = 0.85), indicating that CoP values significantly increased (p < 0.05) with the introduction of the DT. Dual Task Cost (DTC) demonstrated significant effects for Vision (p = 0.008, ηp2 = 0.62), with values varying significantly (p < 0.05) among different vision conditions, especially in CE and Flash conditions. Visual Dependency Quotient (VDQ) analyses revealed significant effects of condition (p < 0.001, ηp2 = 0.84), with significant changes observed in CE/OE and Flash/OE conditions (p < 0.05). Significant effects were observed for Cognitive performance in the Challenge condition (p < 0.001, ηp2 = 0.86), with decreased performance with cognitive task challenges, particularly in Flash and Goggles conditions (p < 0.05). In conclusion, cognitive tasks, especially challenging ones, and visual variations significantly impact postural balance in adolescents with ID.

Variability of Postural Coordination in Dual-Task Paradigm

Postural control is influenced by cognition. In most studies, variability of motor output has been considered regardless of variability in patterns of joint coordination. Uncontrolled manifold framework has been applied to decompose the joint's variance in two components. The first component leaves position of the center of mass in anterior-posterior direction (CoMAP) unchanged (VUCM) while the second component is in charge of variations of CoM (VORT). In this study, 30 healthy young volunteers were recruited. The experimental protocol consisted of three random conditions: quiet standing on a narrow wooden block without a cognitive task (NB), quiet standing on a narrow wooden block with an easy cognitive task (NBE), and quiet standing on a narrow wooden block with a difficult cognitive task (NBD). Results showed that CoMAP sway in NB condition was higher than both NBE and NBD conditions (p = .001). VORT in NB condition was higher than NBE and NBD conditions (p = .003). VORT in NB condition was higher than NBE and NBD conditions (p = .003). VUCM was unchanged in all conditions (p = 1.00) and synergy index in NB condition was smaller than NBE and NBD conditions (p = .006). These results showed that postural synergies increased under dual-task conditions.