Task matters: an investigation on the effect of different secondary tasks on dual-task gait in older adults

Abstract

Background: Dual-task gait performance declines as humans age, leading to increased fall risk among older adults. It is unclear whether different secondary cognitive tasks mediate age-related decline in dual-task gait. This study aimed to examine how type and difficulty level of the secondary cognitive tasks differentially affect dual-task gait in older adults.

Methods: Twenty young and twenty older adults participated in this single-session study. We employed four different types of secondary tasks and each consisted of two difficulty levels, yielding eight different dual-task conditions. The dual-task conditions included walking and 1) counting backward by 3 s or by 7 s; 2) remembering a 5-item or 7-item lists; 3) responding to a simple or choice reaction time tasks; 4) generating words from single or alternated categories. Gait speed and cognitive task performance under single- and dual-task conditions were used to compute dual-task cost (DTC, %) with a greater DTC indicating a worse performance.

Results: A significant three-way interaction was found for the gait speed DTC (p = .04). Increased difficulty in the reaction time task significantly increased gait speed DTC for older adults (p = .01) but not for young adults (p = .90). In contrast, increased difficulty level in the counting backward task significantly increased gait speed DTC for young adults (p = .03) but not for older adults (p = .85). Both groups responded similarly to the increased task difficulty in the other two tasks.

Conclusions: Older adults demonstrated a different response to dual-task challenges than young adults. Aging might have different impacts on various cognitive domains and result in distinctive dual-task gait interference patterns.

Fig. 1

Performance on the cognitive tasks (mean, SE) under single-task standing condition across two difficulty levels between young (N = 20) and older (N = 20) adults. Asterisks indicate significant differences between difficulty levels or between age groups

Fig. 2

Dual-task cost (mean, SE) in gait speed under different task conditions (A: Counting backward; B: Recalling list; C: Reaction time; D: Verbal fluency) between young (N = 20) and older (N = 20) adults. Asterisks indicate significant differences between difficulty levels or between age groups

Fig. 3

Dual-task cost (mean, SE) in cognitive tasks under different task conditions (A: Counting backward; B: Recalling list; C: Reaction time; D: Verbal fluency) between young (N = 20) and older (N = 20) adults. The asterisk indicate a significant difference between the two difficulty levels of the verbal fluency task

Fig. 4

Dual-task interference pattern under four different task conditions (A: Counting backward; B: Recalling list; C: Reaction time; D: Verbal fluency) for the young adults (circles) and older adults (squares). Black symbols represent the easy level of the task; gray symbols represent the difficult level of the task