THE EFFECTS OF 2 TYPES OF COGNITIVE TASKS ON POSTURAL STABILITY IN OLDER ADULTS WITH AND WITHOUT A HISTORY OF FALLS

Background. This study used a dual task design to investigate the effe cts of two different types of cognitive tasks on stability (as measure d by center of pressure displacement) in young vs older adults with an d without a history of falls. Methods. Two secondary cognitive tasks, a sentence completion and a visual perceptual matching task, were used to produce changes in attention during quiet stance under Bat vs comp liant surface conditions in 20 healthy young adults, 20 healthy older adults, and 20 older adults with a history of imbalance and falls. Pos tural stability was quantified using forceplate measures of center of pressure (COP), Speed and accuracy of verbal response on the cognitive tasks were also quantified. Results. During the simultaneous performa nce of a cognitive and postural task, decrements in performance were f ound in the postural stability measures rather than the cognitive meas ures for all three groups. While no differences were found between the young adults and the older healthy adults on the firm surface, no tas k condition, when task complexity was increased (either through the in troduction of a secondary cognitive task, or a more challenging postur al condition such as standing on the compliant surface), significant d ifferences in postural stability between the two groups became apparen t. In contrast to the young and healthy older adults, postural stabili ty in older adults with a history of falls was significantly affected by both cognitive tasks. Conclusion. Results suggest that when postura l stability is impaired, even relatively simple cognitive tasks can fu rther impact balance. Results further suggest that the allocation of a ttention during the performance of concurrent tasks is complex; depend ing on many factors including the nature of both the cognitive and pos tural task, the goal of the subject and the instructions.