The Effect of Cognitive Task, Gait Speed, and Age on Cognitive-Motor Interference during Walking

Abstract

Dual-tasking can cause cognitive-motor interference (CMI) and affect task performance. This study investigated the effects of age, gait speed, and type of cognitive task on CMI during gait. Ten younger and 10 older adults walked on a pressure-sensitive GAITRite walkway which recorded gait speed and step length. Participants walked at a slow, preferred, or fast speed while simultaneously completing four cognitive tasks: visuomotor reaction time (VMRT), serial subtraction (SS), word list generation (WLG), and visual Stroop (VS). Each combination of task and speed was repeated for two trials. Tasks were also performed while standing. Motor and cognitive costs were calculated with the formula: ((single-dual)/single × 100). Higher costs indicate a larger reduction in performance from single to dual-task. Motor costs were higher for WLG and SS than VMRT and VS and higher in older adults (p < 0.05). Cognitive costs were higher for SS than WLG (p = 0.001). At faster speeds, dual-task costs increased for WLG and SS, although decreased for VMRT. CMI was highest for working memory, language, and problem-solving tasks, which was reduced by slow walking. Aging increased CMI, although both ages were affected similarly by task and speed. Dual-task assessments could include challenging CMI conditions to improve the prediction of motor and cognitive status.

Keywords: aging; cognitive–motor interference; dual-tasking; gait; prioritization.

Figure 1

Cognitive tasks are performed in single-task standing. In the visuomotor reaction time task (a), participants stood in front of a TV screen and held a push button in their hand with their elbow flexed to 90°. A red signal or a green signal would flash on the screen, and participants were told to press the button as fast as possible when they saw the green signal appear, as indicated by the *click* in the second image. In the word list generation task (b), participants were given a letter (e.g., F) and asked to list as many words as possible which started with that letter (e.g., face, fancy, fraction, frog, etc.). In the serial subtraction task (c), participants were given a two-digit number (e.g., 70) and asked to count backward by a given one-digit number (e.g., four). For the word list generation and serial subtraction, an example of a researcher-given cue is indicated in black and an example of the participant response is indicated in purple. Lastly, in the visual Stroop task (d), participants were shown a screen with a series of names of colors printed in different colored inks. The participant was asked to read aloud the color of the text in which each word was printed in.

Figure 2

Dual-task gait set-up using the GAITRite pressure-sensitive mat. Participants would walk along the 12 ft mat at either a slow, preferred, or fast gait speed. Cognitive tasks were also performed simultaneously, including the visuomotor reaction time, word list generation, serial subtraction, and visual Stroop. (a) shows an image of a participant completing the serial subtraction task while walking and (b) shows an image of a participant completing the Stroop task while walking. Examples of correct participant responses for each task are indicated in black speech bubbles.

Figure 3

Motor costs for gait speed (a,b) and cognitive costs (c,d) during dual-task gait. Younger and older adults performed the visuomotor reaction time (VMRT), word list generation (WLG), serial subtraction (SS), and visual Stroop (VS) tasks while walking at their slow, preferred, and fast speeds. Higher costs indicate a larger reduction in performance from single-task to dual-task. * indicates a significant difference in costs (p < 0.05) between tasks.

Figure 4

Motor (a) and cognitive costs (b) while performing the Visuomotor Reaction Time (VMRT) task and walking at slow, preferred, or fast speeds in younger and older adults. * indicates a significant difference (p ≤ 0.05) in costs between gait speeds.

Figure 5

Motor (a) and cognitive costs (b) while performing the word list generation (WLG) task and walking at slow, preferred, or fast speeds in younger and older adults. * indicates a significant difference (p ≤ 0.05) in costs between gait speeds.

Figure 6

Motor (a) and cognitive costs (b) while performing the serial subtraction (SS) task and walking at slow, preferred, or fast speeds in younger and older adults. * indicates a significant difference (p ≤ 0.05) in costs between gait speeds.

Figure 7

Motor (a) and cognitive costs (b) while performing the visual Stroop (VS) task and walking at slow, preferred, or fast speeds in younger and older adults. * indicates a significant difference (p ≤ 0.05) in costs between gait speeds.