Brain atrophy and trunk stability during dual-task walking among older adults.

BACKGROUND Dual-task walking is believed to be more cognitively demanding than normal walking and alters trunk movement among older adults. However, the possible association between brain atrophy and spatiotemporal gait parameters, particularly during dual-task walking, is poorly understood. In this study, we examined the relationship between dual-task walking and brain atrophy. METHODS One hundred ten elderly adults (aged 65-94 years, women n = 55) underwent magnetic resonance imaging scanning and gait experiments under normal and dual-task walking conditions. Linear accelerations of the trunk were measured in vertical, anteroposterior, and mediolateral directions using a triaxial accelerometer attached to the lower trunk. Gait speed, stride length, and cadence were recorded. The harmonic ratio, a measure of trunk stability, was computed separately in each direction to evaluate the smoothness of trunk movement during walking. Brain atrophy was quantitatively assessed using magnetic resonance image data. RESULTS Gait speed, stride length, cadence, and harmonic ratio in all directions were lower in dual-task walking than in normal walking (p < .05). The dual-task-related changes in harmonic ratio were independently correlated with brain atrophy adjusted for subject characteristics only in the vertical direction (p < .05). CONCLUSIONS Our findings support the hypothesis that dual-task walking is more cognitively demanding than normal walking. Decreased trunk stability during dual-task walking is associated with brain atrophy. Additional studies are necessary to elucidate the effects of regional brain atrophy on the control of walking.