Effects of a priority-based dual task on gait velocity and variability in older adults with mild cognitive impairment

The purpose of this study to investigate how gait velocity and variability were affected by dual task prioritization in older adults with normal cog-nitive function and older adults with mild cognitive impairment (MCI). Eight older adults with MCI and eight cognitively normal older adults performed a walking task under usual walking with no dual task (usual gait), walk while counting backward from 100 by ones with no priority on task (no priority), walk and count while instructed to prioritize gait task (gait priority), and walk and count while instructed to prioritize the cognitive task (cognitive priority). The MCI group showed significantly slower walking speed than the normal group in the no priority condition, but no difference between both group in the usual gait condition, and they almost 3 times greater gait variability in the no priority condition than the normal group. For the effect of priority instructions, MCI group showed a dual-task cost to gait velocity almost 2 times higher than that of the normal group in the no priority condition, but the cost was almost three times higher in both gait and cognitive priority conditions. Although there was no interaction effect for gait variability, MCI group tended to be more influenced by dual task prioritization than the normal group. Our findings confirmed that the priority-based dual task paradigm is a valid way to assess gait characteristics of people with cognitive problems.