Neural mechanisms underlying the effects of visual input on static balance in older adults with mild cognitive impairment

Objective This study aimed to examine the role of visual information in static balance control and to explore the coupling between brain network topological properties and balance performance in older adults with mild cognitive impairment (MCI). Methods Thirty-four older adults with MCI and 34 cognitively normal (CN) performed two-leg standing tasks with eyes open and eyes closed on a three-dimensional force platform to assess center of pressure indices. fNIRS was used to evaluate the topological properties of brain networks across regions of interest. Results Compared with the eyes-open condition, the MCI group showed significantly greater sway area ( p < 0.001) and anteroposterior RMS ( p = 0.049), along with significantly lower small-worldness ( p < 0.001) and nodal efficiency in the right primary somatosensory cortex (R-S1) ( p = 0.002) under the eyes-closed condition. Similarly, in the CN group, sway area ( p = 0.018) was significantly larger and small-worldness ( p = 0.001) was significantly lower under the eyes-closed condition. Moreover, under the eyes-closed condition, the MCI group exhibited a significantly larger sway area ( p = 0.030) and lower small-worldness ( p < 0.001) than the CN group. Correlation analyses revealed that sway area was negatively correlated with small-worldness in the MCI group ( r = −0.384, p = 0.025), and anteroposterior RMS was negatively correlated with R-S1 nodal efficiency in the CN group ( r = −0.427, p = 0.012). Conclusion Older adults with MCI show reduced balance control under visual restriction. The association between impaired balance and decreased brain network efficiency suggests that disrupted neural organization contributes to balance deficits in MCI.