Age-related Differences in Beta-range Electroencephalography Activity and Its Correlation with Postural Sway during Prolonged Quiet Stance

Falls are a multi-factorial, expensive, and recurring issue in the older population. This study focused on how age affects the cortical activity and its relationship with postural sway during stance. The research sample of eleven healthy, old (mean age = 71 yrs) and ten healthy, young (mean age = 23 yrs) volunteers wore electroencephalography (EEG) caps while balancing on force plates with their eyes closed in a narrow stance on both a hard surface (NEC) and a foam surface (FEC). The EEG power spectral density (PSD) maximum magnitude in the beta range (i.e. 13-30Hz) and the COP peak-to-peak range in the anterior-posterior (AP) and medial-lateral (ML) directions were extracted. The correlation between the EEG PSD and COP range and the corticokinetic coherence between the EEG and contralateral COP were computed. Using one-tailed t-tests, no significant group difference (p\u3e0.06) was found in the EEG PSD percent change between stance conditions. However, there were significant group differences in EEG-COP correlations in both directions (p\u3c0.001); with positive correlation coefficients for the young (mean= 0.29±0.27) and negative for the old (mean= -0.40±0.23). Significant corticokinetic coherence was found for all subjects under both conditions. These results demonstrate a direct communication between cortical activity and postural sway in young and older adults during stance. The cortical-sway relationship, however, is significantly altered in older adults, suggesting an age-related change in the modes of postural control that may be an important indicator for assessing fall-risk