Does attention switching between multiple tasks affect gait stability and task performance differently between younger and older adults?

Gait stability and secondary task performance are affected by the need to share attention when dual-tasking. Further decrements may result from the need to switch attention between multiple secondary tasks. The aim of the current study was to determine the effects of attention switching upon gait stability and task performance in healthy younger and older adults. Ten healthy younger and ten healthy older adults walked on a treadmill at their preferred speed during three trials including: (1) baseline walking; (2) non-switching task walking, requiring response to an auditory-spatial or visual-spatial cue presented in an expected order; and (3) switching task walking, which required response to an auditory-spatial or visual-spatial cue presented in an unexpected order. Response time and accuracy, the margin of stability in the frontal (MoS) and sagittal planes (MoS: anterior, MoS: posterior), step width and step length were calculated for non-switching and switching tasks. The MoS, MoS, MoS, step width and step length during non-switching and switching tasks were normalized to baseline walking. Older adults took significantly longer to respond to cues and made more errors during the switching task compared to younger adults. Younger adults took narrower steps (p < 0.01) and displayed a reduction in MoS (p < 0.01) during the switching task compared with the non-switching task. Conversely, older adults displayed no differences in MoS between tasks. These findings suggest that attention switching results in different task prioritization strategies in younger and older adults during walking.