Interaction between delayed visual feedback and secondary cognitive tasks on postural control in older adults

Age-related decline in control mechanisms and sensory information detection adversely affect balance in older adults. This effect is particularly pronounced during the performance of a concurrent cognitive task. The purpose of this experiment was to determine the effects of cognitive load and the temporal salience of delayed visual feedback (DVF) on the stability of upright stance in older individuals. Fifteen healthy young and fifteen healthy older subjects participated. Participants were required to position their centre of pressure (COP) as close to a fixed-target as possible on an LCD monitor. In a set of experimental conditions the delay with which the visual feedback was made available to the participants was systematically varied. The cognitive dual-task involved the performance of a simple serial arithmetic operation. Visual feedback conditions consisted of eyes-open (no COP feedback) and DVF conditions (0, 300, 600, 900 ms). While sway variability increased with visual delay in both groups, older participants exhibited greater sway variability across all DVF conditions. Young adults showed a reduction in AP COP variability in the dual DVFcognitive task performance conditions Older adults, in contrast, did not benefit from cognitive dualtask performance. We argue that this reflects insufficient or inappropriate modulation of attention resulting in compromised balance control in older individuals.