The Impact of Dual Tasking on the Vestibulo-Ocular Reflex

Introduction: Our daily life comprises dual-task activities requiring stable gait and postural. The Vestibulo-Ocular-Reflex (VOR) is one of the key components in balance control. The VOR enables gaze stabilization during head movements and constantly adapts to environmental changes which is critical for gait and balance control. Various studies have shown that either cognitive or motor activity adversely affects balance function and vice versa. We aim to assess the impact of cognitive and motor dual tsking on the VOR function and to evaluate the VOR adaptability to changing target distance by using the video head impulse test (vHIT).

Methods: In total, 16 healthy young adults performed 14 assignments: single task vHIT to far and near targets, single task cognitive, single task motor, and dual-task cognitive/motor tasks with vHIT to far and near targets. Two types of activities were chosen for the cognitive and for the motor tasks. vHIT testing was performed with a near target at 15 cm, and a far target at 1.5 meters. A paired t-test was used to evaluate the difference in VOR gains and adaptability abilities between single and dual tasking conditions.

Results: No difference in VOR gains or VOR gain ratios (near VOR gain/far VOR gain*100 = adaptability) was demonstrated between single-task vHIT and either dual-tasking conditions (cognitive or motor). Similar VOR gain was observed between dual tasking with far and near objects. No difference was found between the cognitive and motor dual-tasking effects.

Conclusions: Gaze stability has been shown to be a robust reflex with a low sensitivity to different external loads. Therefore, it may not be necessary to include dual-tasking exercises during gaze stability rehabilitation, unlike general balance rehabilitation.