Older fallers with poor working memory overestimate their postural limits

Objective: To compare the accuracy of perceived postural limits between older fallers with good working memory and those with poor working memory. Design: Cross-sectional study. Setting: Research laboratory. Participants: Thirty-three community-dwelling older adults with a history of falls. Interventions: Not applicable. Main Outcome Measures: We measured the accuracy of perceived postural limits by using the perceived reach test in 33 fallers. The difference between the verbal digits forward test score and the verbal digits backward test score was used to provide an index of the central executive component of working memory. Participants were then allocated into 2 groups: (1) good working memory or (2) poor working memory. Comparisons of group characteristics and scores were undertaken by using Student independent-sample t tests for differences in means between those with good working memory and those with poor memory. One hierarchical linear regression model was constructed to determine the independent association of the central executive component of working memory with the accuracy of older fallers' perceived reach capacity. Results: There was a significant difference in the mean percentage error in perceived reach between older fallers with good working memory and those with poor working memory (P=.01). The verbal digit span difference score was independently associated with the percentage error in perceived reach. The verbal digit span difference score resulted in an R2 change of 18.2% and significantly improved the regression model (F1,26 change, 7.45; P=.01). Conclusions: Our novel results suggest that impaired executive functioning may increase falls risk by impairing older adults' judgment in motor planning for daily activities. However, future studies with larger sample sizes are needed to confirm our current results.