Muscle strength, EEG biomarkers, and working memory as interacting predictors of cognitive function in cognitively impaired older adults.

Background: Cognitive decline in older adults is a pressing public health concern, with emerging evidence suggesting that both muscle strength and neural function may influence cognitive outcomes. However, the integrative mechanisms linking these domains remain insufficiently understood.

Objective: This study aimed to explore whether resting-state EEG characteristics and working memory mediate the relationship between muscle strength and global cognitive function in older adults with cognitive impairment. Methods: A cross-sectional study was conducted among 137 older adults (mean age = 72.65 ± 7.75) with cognitive impairment. Muscle strength was assessed using grip strength and 30 s chair stand tests. Resting-state EEG power across six frequency bands was recorded from 16 electrodes. Working memory was evaluated using a two-back task, and cognitive function was assessed via the MoCA. Mediation analyses were performed using the PROCESS macro (Model 4), controlling for age, sex, education, and BMI.

Results: Grip strength showed significant direct effects on cognitive function (β = 0.399, p < 0.001), with partial mediation by both working memory (β = 0.070, p < 0.05) and resting-state EEG (β = 0.150, p < 0.01). In contrast, lower limb strength was mediated only by working memory (β = 0.078, p < 0.05), while EEG-based mediation was not significant. The overall model explained 50.7% of the variance in cognitive outcomes.

Conclusion: This study highlights the distinct mediating roles of working memory and EEG features in the muscle strength-cognition relationship. Grip strength, as a potential biomarker, may reflect central nervous system integrity and serve as a target for cognitive health interventions in aging populations.