Age-related changes in prefrontal activity during walking in dual-task situations: a fNIRS study

BACKGROUND: Previous studies suggest that the human gait is under control of higher-order cognitive processes, located in the frontal lobes, such that an age-related degradation of cognitive capabilities has a negative impact on gait.

METHODS: Using functional Near-Infrared-Spectroscopy (fNIRS) we investigate the frontocortical hemodynamic correlates of dual-task walking in two conditions. 15 young and 10 older individuals walked on a treadmill while completing concurrent tasks that had either visual (checking) or verbal-memory (alphabet recall) demands. We compared subjects' motor performance, as well as their prefrontal activity in single- and dual-task walking.

RESULTS: Our behavioral data partly confirm previous accounts on higher dual-task costs in stepping parameters (i.e., decreased step duration) in old age, particularly with a visual task and negative dual-task cost (i.e., improved performance) during the verbal task in young adults. Functional imaging data revealed little change of prefrontal activation from single- to dual-task walking in young individuals. In the elderly, however, prefrontal activation substantially decreased during dual-task walking with a complex visual task.

CONCLUSION: We interpret these findings as evidence for a shift of processing resources from the prefrontal cortex to other brain regions when seniors face the challenge of walking and concurrently executing a visually demanding task.