Dual Tasking Under Compromised Visual and Somatosensory Input in Elderly Fallers and Non-Fallers

Background: Performance of additional tasks disturbs postural control in elderly. It is unknown, however, how postural control is affected in elderly fallers and non-fallers in a reduced sensory situation. Objective: To compare differences between single and dual tasking in three test conditions; (1) no-vision, (2) under reduced somatosensory information and (3) with a combination of both conditions. Design: An observational cohort study with participants assigned to a 12-month pretest fall assessment and a postural balance assessment. Methods: Fifteen independently living elderly participated (77.5 ± 7.0 [63-87] years). Falls were pre-assessed with a 1- year monthy “fall calendar”. Postural control was analyzed by means of a force platform. Participants were standing quiet (first task) while counting backwards (second task). A 2-factor (group x condition) ANOVA was performed at p<.05. Differences of postural (DTCp) and cognitive dual task costs (DTCc) between test conditions were analyzed (one-way ANOVA). Results: The analysis showed significant group (fallers/non-fallers) and condition effects. Post hoc analyses indicated that the postural control variables were significantly different during the concurrent reduced vision and somatosensory information. Dual task costs showed a significant difference between normal (N) and the combined condition (NV+RP) in non-fallers. Conclusion: The combination of reduced visual and somatosensory information causes a larger disturbance of postural stability compared with the reduction of visual or somatosensory information alone. Non-fallers seem to have no threats to the postural control stability in this combined reduced sensory situation. They reduce their postural control, which leaves them enough resources to compensate for the reduced sensory information.