Changes in gait while backward counting in demented older adults with frontal lobe dysfunction

Background Gait disorders caused by dementia have been associated with frontal lobe dysfunction. Dual-tasking is used to explore the involvement of cortical level in gait control. It has been shown that dual-task induced gait changes that could be related to (1) the efficiency of executive function, (2) the level of difficulty involved in the walking-associated task, or (3) the articulo-motor components comprised in the walking-associated task. A better understanding of dual-task related changes in demented subjects with frontal lobe dysfunction could help us to clarify the role of the frontal lobe in motor gait control. Objective To assess and compare the effects of two mental arithmetic tasks involving similar articulo-motor components but different level of difficulty on the mean values and coefficient of variation (CV) of stride time among demented older adults with impaired executive function. Methods The mean values and coefficients of variation of stride time were measured using a GAITRite®-System among 16 demented older adults with impaired executive function while walking with and without forward counting (FC) and backward counting (BC). Results The mean values and CV of stride time were significantly higher under both dual-task conditions than during a simple walking task (p < 0.05). The change in CV of stride time during BC was significantly higher when compared with the change during FC (p = 0.015), whereas the change in mean value was not significant (p = 0.056). There was no difference between the dual-task and single task condition as far the number of enumerated figures were concerned (p = 0.678 for FC and p = 0.069 for BC), but significantly fewer figures were enumerated while BC compared with FC (p < 0.001). Conclusion BC provoked more changes in gait parameters than FC with major modification in gait variability related to an inappropriate focusing of attention. These findings suggest that the CV may be a suitable criterion for the assessment of gait control.