Physiological and Cognitive Determinants of Dual-Task Costs for Gait Parameters: The Yishun Study

BACKGROUND Studies indicate that physiological and cognitive aging are causally related and functionally interdependent. However, the relative contribution of physiological factors and cognition to dual-task costs (DTC) of gait parameters has not been well studied. In this cross-sectional study, we examined the trajectory of DTC of gait parameters across the adult age spectrum for both sexes and identified the contributions of physical and cognitive performance to DTC of gait. METHODS A total of 492 community-dwelling adults, aged 21-90 years, were randomly recruited into the study. Participants were divided into 7 age groups, with 10-year age range for each group. Demographic data, height, body mass, education level, and information on comorbidities were recorded. Cognition was measured using the Repeatable Battery for the Assessment of Neuropsychological Status. Physical performance included visual contrast sensitivity, postural sway, hand reaction time, handgrip strength, knee extensor strength, and single-task and dual-task gait assessments. Stepwise multivariable regression was used to examine the association between physical and cognitive performance with DTC of gait parameters. RESULTS Women were found to have significantly higher DTC of gait speed (p = 0.01), cadence (p < 0.01), and double support time (p < 0.01) than men. However, significant aging effect on DTC of gait speed (p = 0.01), step length (p = 0.01), and double support time (p = 0.01) was observed in men but not in women. Immediate memory was the primary determinant for the DTC of gait speed (β = -0.25, p < 0.01), step length (β = -0.22, p < 0.01), and cadence (β = -0.15, p = 0.03) in men. Besides immediate memory, postural sway (β = -0.13, p = 0.03) and hand reaction (β = 0.14, p = 0.02) were also significantly associated with DTC of step length and cadence, respectively, in women. CONCLUSION There were sex differences in the amplitude and trajectories of DTC of gait parameters. The DTC increased with age in men but not in women. Immediate memory was the primary determinant of DTC of gait parameters in men while immediate memory, postural sway, and reaction time were associated with DTC of gait in women. Future studies should investigate the clinical implications of the sex differences in the DTC with fall risks.