P40. Quantitative gait parameter changes under challenging single and dual tasking conditions are associated with Trail Making Test performance: Cross-sectional analysis in 661 elderly

Abstract

Background Supraspinal control of gait is a relevant factor of healthy ageing, quality of life and is regularly affected in neurodegenerative disorders. The function of supraspinal control mechanisms is, at least partly, dependent on executive function, and can be assessed quantitatively with challenging single and dual task paradigms. Until now, the most promising paradigms and parameters are not defined which test this system, although measures of gait variability seem most often affected. Methods In the frame of the TREND study ( www.trend-studie.de ), gait was assessed under three conditions in a cohort of 661 non-demented individuals aged 50 to 80 years: All participants performed 20-meter walks at maximum speed (1) without a secondary task, (2) with checking boxes on a clipboard simultaneously, and (3) with subtracting serial 7s simultaneously. Quantitative gait parameters were recorded with a sensor unit (Dynaport®, McRoberts) worn at the lower back during walking. The Trail Making Test (Delta TMT) as a measure of executive function was used to categorize the participants in cohorts with poor, intermediate, and good cognitive flexibility. Good TMT performers were then compared with poor TMT performers regarding quantitative gait parameters. Results From the assessments, walking when subtracting 7s showed largest differences between good and poor TMT performers, followed by the walking when checking boxes task and the walking task. Among the parameters analysed, gait speed (p 0.0001) and step frequency (p = 0.0004) differentiated best between the above cohorts. Moreover, both good and poor TMT performers showed decreased gait variability when checking boxes compared to single task walking (p 0.01). Good, but not poor TMT performers, showed significantly higher gait variability during the subtracting task when compared with the checking boxes task (good p 0.0001, poor p = 0.44). Conclusion This large cohort study confirms results from previous studies with smaller cohorts showing that assessments of challenging conditions with the use of a sensor unit can detect subtle changes in gait between good and poor TMT performers. Moreover, gait variability changes among the groups suggest that good and poor TMT performers use different strategies to adapt to the complexity of the task, when performing challenging secondary tasks simultaneously with walking.