2025, Vol. 29 ›› Issue (8): 1643-1649

Differences in postural control ability between older adults with mild cognitive impairment and those with normal cognition under different single-task and dual-task conditions

Zhang Yuxin1, Yu Cong1, Zhang Cui2, Ding Jianjun1, Chen Yan3   

Abstract: BACKGROUND: The decreased postural control ability due to mild cognitive impairment in elderly people leads to the increased risk of falls. Dual-task is the primary research paradigm for evaluating the relationship between cognition and postural control in the scenes close to real life. The sample entropy of the plantar center of pressure (COP) displacement during standing can represent the complexity of postural control.
OBJECTIVE: Based on the COP displacement sample entropy, to analyze the differences in postural stability characteristics and control strategies between older adults with mild cognitive impairment and cognitively normal older adults during the dual-task with postural control and spatial working memory, aiming to explore the impact of cognitive impairment on the postural control ability during standing.
METHODS: Sixteen older adults with mild cognitive impairment and 17 cognitively normal older adults were eligible and selected for the study. They completed five test tasks, including spatial working memory, double-feet balance stance, Romberg stance, double-feet balance stance-spatial working memory dual-task, and Romberg stance-spatial working memory dual-task, with three valid completions of each task. The plantar COP data were collected by the Kistler 3D force platform. The indicators included cognitive behavior (cognitive score and reaction time) and kinematic indexes (COP displacement and sample entropy).
RESULTS AND CONCLUSION: The older adults with mild cognitive impairment performed the spatial working memory task with the greatest cognitive score and the shortest reaction time, the double-feet balance stance-spatial working memory dual-task with moderate cognitive score and reaction time, and the Romberg stance-spatial working memory dual-task with the smallest cognitive score and the longest reaction time, where the differences were significant among the tasks (P < 0.05). In the older adults with mild cognitive impairment, the anterior-posterior and medial-lateral COP displacements were significantly greater, and their sample entropy values were significantly smaller in the double-feet balance stance-spatial working memory dual-task and Romberg stance-spatial working memory dual-task than in the double-feet balance stance and Romberg stance tasks (P < 0.05). In the spatial working memory task, there were no significant differences in cognitive score and reaction time between the both groups (P > 0.05); however, in the double-feet balance stance-spatial working memory dual-task and Romberg stance-spatial working memory dual-task, cognitive scores were significantly smaller and reaction times were longer in the older adults with mild cognitive impairment compared with the cognitively normal older adults (P < 0.05). In the double-feet balance stance-spatial working memory dual-task and Romberg stance-spatial working memory dual-task, the older adults with mild cognitive impairment exhibited significantly greater anterior-posterior and medial-lateral COP displacements and significantly smaller sample entropy values compared with the cognitively normal older adults
(P < 0.05). All findings indicate that compared with cognitively normal older adults, older adults with mild cognitive impairment exhibit smaller complexity, poorer systematic adaption and decreased automatic regulation of the postural control during performing the dual-tasks, who are more susceptible to spatial working memory interference, leading to the increased risk of falls.
Key words: mild cognitive impairment, older adults, spatial working memory, postural control, dual-task, sample entropy