Cognitive task modality influences postural control during quiet standing in healthy older adults

Background The interstimulus interval of a cognitive task was found to have a limited effect on postural control in young adults, while visual cognitive tasks were found to improve stability compared to auditory tasks. It is of interest to investigate whether postural control in healthy older adults is sensitive to these types of cognitive task manipulations. Aims The objectives of the present experiment were to evaluate the impact of interstimulus interval and modality of a continuous cognitive task on postural control in healthy older adults. Methods Fifteen healthy older adults (70 +/- 3.2 years, 3 male) were asked to stand with feet together on a force platform while performing auditory and visual cognitive tasks performed with interstimulus intervals of 2 and 5 s. Results Visual tasks led to reductions in sway area and sway variability in the anterior-posterior direction compared to auditory tasks (ps <= 0.05). The interstimulus interval did not lead to a change in sway, except for a small change in the medial-lateral direction for the 2-s interval compared to the 5-s interval (p = 0.05). Discussion and conclusions Results suggest that the interstimulus interval had a very limited effect on postural sway. The modality of the cognitive task had a greater effect on postural sway, as visual cognitive tasks yielded smaller sway area and anterior-posterior sway variability than auditory conditions. Visual stimuli may have acted as an anchor, yielding reduced sway.