No abstract

Among healthy older adults, individuals with poorer EF are more prone to falls. Higher-level cognitive functions such as those regulated by the frontal lobes are apparently needed for safe everyday navigation that demands multitasking. Optimal screening, early detection, and treatment of falls should, apparently, also target this cognitive domain.

Background: The ‘timed up and go’ test (TUG) is a simple, quick and widely used clinical performance-based measure of lower extremity function, mobility and fall risk. We speculated that its properties may be different from other performance-based tests and assessed whether cognitive function may contribute to the differences among these tests in a cohort of healthy older adults. Objective: To evaluate psychometric properties of the TUG in healthy older adults in comparison to the Berg balance test (BBT) and the Dynamic Gait Index (DGI). Methods: The TUG, DGI and BBT were assessed in 265 healthy older adults (76.4 ± 4.3 years; 58.3% women) who participated in a 3-year prospective study. The Mini-Mental State Examination, digit span and verbal fluency measured cognitive function. The one-sample Kolmogorov-Smirnov test evaluated deviations from a normal distribution and Pearson’s correlation coefficients quantified associations. Results: The mean scores of the BBT, DGI and TUG were: 54.0 ± 2.4, 22.8 ± 1.5, 9.5 ± 1.7 s, respectively. The BBT and the DGI were not normally distributed (p < 0.001), but the TUG was (p = 0.713). The TUG times were mildly associated (p < 0.01) with digit span and verbal fluency and were related to future falls, while the BBT and the DGI were not. Conclusions: The TUG appears to be an appropriate tool for clinical assessment of functional mobility even in healthy older adults. It does not suffer from ceiling effect limitations, is normally distributed and is apparently related to executive function. The BBT and the DGI do not share these beneficial properties. Perhaps the transferring and turning components of the TUG help to convert this relatively simple motor task into a more complex measure that also depends on cognitive resources.

Background The factors that contribute to the dual task (DT) changes in performance that occur when older adults walk while simultaneously performing other tasks are not well-known. We hypothesized that cognitive and motor reserve (e.g., executive function, EF, postural control, and walking abilities) and affect (e.g., anxiety, depressive symptoms) influence the DT decrements (DTDs) in gait. Methods 228 community-living, healthy older adults (mean: 76.2±4.2 yrs; 59% women) walked with and without dual tasking, e.g., subtracting 7’s, phoneme monitoring. Mobility (e.g., the Dynamic Gait Index), cognitive function (e.g., memory, EF), and affect (e.g., Geriatric Depression Scale) were quantified. Bivariate and multivariate analyses identified factors associated with the DTD in gait speed (a general measure of locomotor function), swing time, (reflecting balance during gait), and swing time variability (a measure of stride-to-stride consistency). Results Gait speed and swing time decreased (p<0.001) and swing time variability increased (became worse) (p<0.001) during all DTs. The DTD in gait speed was correlated with comfortable-walking gait speed, but not with tests of mobility or cognitive function. The DTD in swing time variability was correlated with EF, mobility and affect (e.g., depressive symptoms). Much of the variance in the DTDs was unexplained. Conclusions Usual-walking abilities and cognitive function contribute to the DT effects on gait, but these relationships depend on specifics of the DT, the gait feature being studied, and the particulars of the cognitive domain. Meeting the everyday challenges of walking while dual tasking apparently relies on multiple factors including a consistent gait pattern and EF.