Spatial task-related brain activity and its association with preferred and fast pace gait speed in older adults.

Task-related brain activity is associated with preferred pace gait speed in older adults. Whether similar regional brain activity relates to fast pace gait speed has yet to be determined, but may provide insight into neural substrate important for walking under various conditions. This study measured regional blood-oxygen-level dependent (BOLD) changes using functional magnetic resonance imaging (fMRI) in response to a spatial Simon/Stroop task in community-dwelling older adults (N = 20, 63-80y). Preferred pace, fast pace, and dual-task gait speeds (picking up objects at preferred pace; fast walking over obstacles) were measured across a 7-meter course. Time to complete a fast pace 400 m walk test was also recorded. Partial correlations were used for all analyses after adjusting for age. Accuracy on incongruent trials of the spatial task was positively correlated with all fast walking conditions (all p < 0.01), but not preferred pace walking conditions. BOLD signal change in the left middle frontal gyrus during the spatial task was associated with preferred pace gait speed (r = 0.51, p = 0.02) and fast walking over obstacles (r = 0.53, p = 0.01). Interestingly, BOLD signal change in the bilateral precuneus was associated with fast pace gait speed (r = 0.58, p < 0.01), fast walking over obstacles (r = 0.48, p = 0.03), and 400 m walk time (r=-0.49, p = 0.02). These results find preferred and fast pace gait speed are associated with different regional task-related brain activity, with activation in the precuneus related with greater performance during fast pace walking.