Multisystem Functional Burden and Complex Gait Under Memory Interference in Community-Dwelling Older Adults

This cross-sectional study examined complex gait (CG) under auditory-verbal memory interference and eye–hand coordination (EHC) under visual-perceptual interference in community-dwelling older adults (31 men, 67 women; 68.26 ± 5.05 years), focusing on dual-task susceptibility, age- and sex-related differences, and multisystem functional burden. Participants completed assessments of CG, maximum gait speed, handgrip strength, EHC, cognitive function, and physical activity, with CG and EHC evaluated under dual-task conditions. Results showed that CG performance deteriorated under auditory-verbal memory interference, whereas EHC performance deteriorated under visual-perceptual interference (both p < 0.001). Under interference, CG was associated after adjustment for age and sex with handgrip strength (p = 0.020), gait speed (p < 0.001), and EHC (p < 0.001). Gait speed demonstrated a non-linear relationship with CG, revealing disproportionately poorer performance at lower speeds. Exploratory non-linear analyses also suggested possible age-related changes in CG trajectories; however, these findings were sample-sensitive and should be interpreted cautiously, whereas linear models adequately captured the overall age-related trend. Furthermore, higher multisystem functional burden—integrating cognitive, locomotor, muscular, and visuomotor parameters—was associated with poorer CG performance both without interference (p = 0.001) and under memory interference (p < 0.001), as well as with greater raw dual task cost (p = 0.004). Ultimately, CG under memory interference reflects the convergence of integrated physical and cognitive capacities rather than isolated walking ability, highlighting maximum gait speed and multisystem burden as valuable parameters within a research framework for evaluating functional reserve in older adults.