Cognitive Demands of Postural Stability in the Older Adult

Abstract

0614 Falls are the leading cause of accidental death in older adults. Impaired balance is a significant factor accounting for the increased incidence of falls experienced by older adults. When attempting to identify the variables contributing to poor balance, most studies have focused on the physical aspects of balance. Few studies have examined the impact of cognition on postural control. PURPOSE: The purpose of this study was to utilize a dual-task paradigm and examine the effect of several cognitive domains on postural stability in older adults. METHODS: Twenty-five individuals (age = 75.33 ± 7.26 years) completed six cognitive tasks (Useful Field of View (UFOV) task 2, UFOV task 3, Stroop word and color, Manikin, and Math) while standing on a balance platform. Sway amplitude in the anterior-posterior (AP) and medial-lateral (ML) planes were recorded during both dual (balance and cognitive task) and single (balance only) conditions. RESULTS: Postural sway was greater under dual-verses single-task conditions and was believed to be mediated by task difficulty and not a specific cognitive process. Repeated-measure ANOVAs were significant for sway amplitude in the ML (F1,6 = 27.39, p ≤ Ü 0.01) and AP direction (F1,6 = 18.05, p ≤Ü 0.01). Post hoc analysis revealed a distinct grouping of the cognitive variables. Results are summarized by grouping manikin, UFOV3, and Stroop color (Group 1), and Stroop word, math and UFOV2 (Group 2). Tasks in Group 1 were significantly different (p ≤Ý 0.01) from balance only and tasks in Group 2. Excluding Stroop word, tasks in Group 2 were significantly different (p ≤Ü 0.01) from balance only and all Group 1 tasks. The distinction between tasks in Group 1 and Group 2 is believed to be related to their relative task difficulty with participants ranking Group 1 tasks as difficult and Group 2 tasks easy. CONCLUSION: Results support the findings of others demonstrating that cognitively demanding tasks interfere with postural stability. This is true despite the fact that the maintenance of balance is often regarded as a highly automated task and as such, should not be negatively affected by a secondary cognitive task. Pashler's response selection bottleneck model was used to describe the relationship between cognition and postural sway. It is likely that more effortful tasks place greater demands on and thus lengthen the decision-making stage resulting in a delay in the execution of sway reducing postural adjustments.