Spatial variability during gait initiation while dual tasking is increased in individuals with mild cognitive impairment

Abstract

Background: Gait initiation (GI) is a complex transition phase of gait that can induce postural instability. Gait impairment has been well documented in people with Alzheimer's disease, but it is still inconclusive in individuals with Mild Cognitive Impairment (MCI). Previous studies have usually investigated gait performance of cognitive impaired persons under steady state walking. Objective: This study aimed to examine spatiotemporal variability during GI under single- and dual-task conditions in people with and without MCI. Methods: Spatiotemporal stepping characteristics and variability under single- and dual-task conditions (counting backwards by 3s) were assessed in 30 older adults with MCI and 30 cognitively intact controls. Mean and coefficients of variation (COV) of swing time, step time, step length and step width were compared between the two groups. Results: Mixed-model repeated measures ANOVA revealed a significant Group x Walking condition interaction for COV of step length and step width (P<0.05). Post-hoc analysis revealed that variability for these measures were significantly larger in the MCI group compared with the control group under the dual-task condition (P<0.05). Conclusions: Step length and step width variability is increased in people with MCI during GI, particularly in a condition involving a secondary cognitive task. These findings suggest that individuals with MCI have reduced balance control when undertaking a challenging walking task such as gait initiation, and this is exacerbated with an added cognitive task. Future studies should prospectively investigate the relationship between GI variability and fall risk in this population.