Attentional demands and postural control: the effect of sensory context.
BACKGROUND
This study used a dual task design to examine the effect of sensory context on postural stability during the concurrent performance of an attentionally demanding cognitive task in young and older adults with and without a history of imbalance and falls.


METHODS
A choice reaction time auditory task was used to produce changes in attention during quiet stance in six different sensory conditions that changed the availability of accurate visual and somatosensory cues for postural control. Postural stability was quantified by using forceplate measures of center of pressure in 18 young adults, 18 healthy older adults, and 18 older adults with balance impairments and a history of recent falls. Reaction time and accuracy of verbal response to the auditory task were quantified by using a repeated measures analysis of variance.


RESULTS
In young adults the auditory task did not affect postural stability in any of the sensory conditions. However, in the older adults the effect of the auditory task depended on sensory context. For healthy older adults, the addition of an auditory tone task significantly affected sway only when both visual and somatosensory cues for postural control were removed. In the balance-impaired older adults, the addition of the auditory task significantly affected postural stability in all sensory conditions. In addition, as sensory conditions became more difficult, older adults who had been able to maintain stability in a single task context lost balance when performing a secondary task.


CONCLUSIONS
Results suggest that with aging, attentional demands for postural control increase as sensory information decreases. In addition, the inability to allocate sufficient attention to postural control under multitask conditions may be a contributing factor to imbalance and falls in some older adults.
Shumway-Cook
A
A
Department of Rehabilitation Medicine, University of Washington, Seattle 98195, USA. ashumway@u.washington.edu
Woollacott
M
M
D000058:Accidental Falls; D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology*; D013647:Task Performance and Analysis; D016138:Walking / Q000502:physiology