Dual-task effects of spontaneous speech and executive function on gait in aging: exaggerated effects in slow walkers.

This study compared the effects of spontaneous speech and executive function on gait and investigated the effects of single-task gait speed on dual-task costs. Twenty-one older adults (74.7 years, SD 5.9) and 23 younger adults (22 years, SD 1.2) walked for 60s while performing an auditory Stroop task and a spontaneous speech task; they also performed each task in isolation. Walking while talking significantly reduced gait speed in both groups; however, only older adults experienced significant cognitive-motor interference during the Stroop task. Stride duration variability and gait symmetry were also affected by the speech task in older but not younger adults. Dual-task costs on gait speed were greater in slow-walking older adults than fast walkers. These results demonstrate that spontaneous speech is a highly demanding task that has a profound impact on gait in older adults, especially those with gait speed <1 m/s.