Development of a Clinical Measure of Dual-task Performance in Walking: Reliability and Preliminary Validity of the Walking and Remembering Test

Journal of Geriatric Physical Therapy, 2009 by McCulloch, Karen L, Mercer, Vicki, Giuliani, Carol, Marshall, Steve

ABSTRACT

Objectives: (1) To examine the reliability of a new clinical measure of simultaneous walking with performance of a working memory task, the Walking and Remembering Test (WART). (2) To compare older adult to younger adult WART performance to illustrate preliminary validity.

Subjects: Convenience sample of 25 young adults (ages 22-35) and 25 older adults (ages 65-86) performed the WART twice.

Methods: Subjects walked 6.1 meters at their fastest safe speed along a path requiring a narrowed base of support in both single and dual-task (with simultaneous digit span task) conditions. Reductions in walking and cognitive performance were examined in the dual-task condition for older adults as compared to younger adults.

Main outcome measures: Walking time, step accuracy, digit span memory accuracy, and dual-task costs for walking and cognitive tasks.

Results: Inter-rater reliability ICC (2,1) values were ≥ .97 for walking time and digit span accuracy. Rater agreement of steps off the path was excellent (93%) for young adults and good (76%) for older adults. Test-retest reliability ICC (2,1) values for walking time were ≥ .79. Older adults were slower and remembered shorter digit spans, and demonstrated greater dual-task costs for digit span accuracy and steps off the path than younger adults, but relative dual-task costs for walking time were not significantly different between groups.

Conclusions: The WART is a reliable clinical measure of dual-task memory and walking that can be administered safely with community-dwelling older adults. Expected greater dual-task costs for older adults were observed, but not as strongly as anticipated in this group of very active subjects. The WART provides information that may be useful in targeting patients for intervention to reduce risk of falls in dual-task conditions, but needs validation with older adults across a greater range of walking ability.

Key Words: reliability, dual-task conditions, walking, older adults

INTRODUCTION

The ability to attend to, and perform, two tasks at the same time, described as dual-task performance, has been shown to decline in people as they age.1 Clinical tests that require dividing attention between two tasks have been developed to characterize age-related changes in the effects of cognition on balance and safety. The inability to walk and talk, or to walk while carrying an object at the same time has been associated with falls risk in frail older adults.2,3 Older adults with a history of falls also have more difficulty maintaining balance in challenging sensory conditions while performing a concurrent cognitive task.4,5 Given the public health implications of falls in older adults, the association between dual-task performance and falls risk is an important area for investigation.

Existing clinical measures that assess dual-task performance with a cognitive task during walking include: the "stops walking while talking" test (SWWT),2 the Timed Up and Go cognitive (TUG cognitive),4 the Walking WhUe Talking Test (WWTT),6 and the Multiple Tasks Test (MTT)7,8 (Table 1). These tests have important limitations for identifying dual-task performance problems in community-dwelling older adults. The SWWT, TUG cognitive test, and the WW Tl present cognitive tasks as distracters. No effort is made to characterize the performance of the cognitive task prior to walking or during walking.

Task difficulty is an important consideration in dual-task performance.9 All of the published clinical tests of dual-task walking performance require walking at a self-selected speed, a task that for community-dwelling older adults may leave significant "reserve capacity" for the performance of other tasks. Furthermore none of the current clinical tests attempt to provide a level of cognitive challenge that takes into account the individual's capacity for the task. Education or literacy level may affect the ability to perform these tasks, making them simple for some but very challenging for others. For community dwelling older adults, the ease of talking (SWWT), responding to simple questions (MTT), reciting the alphabet (WWTT), or performing simple subtraction (TUG cognitive) may allow a reserve capacity so that dual-task costs are not observed in clinical settings.

There is a need for a clinical measure that provides sufficient challenge on both tasks to elicit dual-task costs in a way that can be easily observed by a clinician. The Walking and Remembering Test was designed to meet this need by characterizing dual-task performance in a manner similar to Lindenberger et al,10 but for use in clinical settings. Lindenberger et al devised a protocol for experimental assessment of the single and dual-task demands during walking in active older adults.10 In this study, adult subjects in three age groups (20-30, 40-50, and 60-70 years) walked on 19 cm narrow tracks while performing a verbal memory task. Walking trials were 170 seconds long to allow presentation of 16 item word lists via headphones. Electrically conductive walking tracks and shoes equipped with one graphite sole and one aluminum tape sole allowed instrumented assessment of the number of steps off the tracks as subjects walked as quickly and as accurately as possible. Significant dual-task costs were demonstrated in die oldest age group in the dual-task condition, as reflected by greater relative dual-task costs in walking speed, poorer step accuracy, and reduced word recall. These laboratory methods were effective in illuminating relationships between dual-task costs in mobility and cognition, but are not feasible for use in the clinical setting. In this paper, we describe development of the WART and provide evidence for its reliability and preliminary validity.