Influence of various cognitive tasks on gait speed and dual task costs in patients with mild cognitive impairment

Objective: Previous studies show that dual-task gait (DTG) speed is an indicator of the progression of mild cognitive impairment (MCI) to Alzheimer's Disease (AD). However, the influence of different cognitive tasks on gait speed and dual-task costs (DTC) remains unclear in such patients. Our study was aimed to investigate this influence. Method: All the participants went through dual-task gait analysis in a gait lab using two-meter electronic walkways(Zebris, FDM-2). Each participant completed one single-task walk and four dual-task walks (walk with calculation, animal naming, story memory and words memory respectively) with self- selected speed. Gait speed and DTC were calculated based on the captured data. DTC was defined as the percentage change between single and dual- task gait speed: [(single- task gait speed-dual- task gait speed)/single- task gait speed]×100. One way ANOVA and subsequent post-hoc tests were applied to compare the DTC performance of various cognitive tasks in patients with MCI and normal cognitive (NC) sample. While independent samples t-test was used to analyze the difference of DTC with each cognitive task between groups. Result: Totally 18 participants diagnosed with MCI and 25 normal controls were included in this study. The characteristics including age, gender and education years were balanced between groups (P>0.05). One- way- ANOVA showed significant difference in all four cognitive tasks in MCI patients (P=0.004) and NCs (P= 0.010). The independent t-test showed that only DTC of words memory in MCI group was significantly higher than the NCs (P=0.034). Conclusion: Dual- task costs have significant differences among different cognitive tasks in MCI patients and NCs. Words memory task has the highest cognitive cost in patients with MCI comparing to NC.