The Association of Turns, Mild Parkinsonian Signs and Falls in Older Adults

Abstract

Research has shown that turns are associated with falls in clinical populations of older adults. However, limited research has been conducted on walking turns in healthy older adults. There is a growing body of research on the presence of mild Parkinsonian signs (MPS) in older adults, and the effects these symptoms have on individuals' functioning as well as prognosis. Recently, MPS has been shown to be related to gait performance. Given that individuals with Parkinson's disease (PD) report more falls and demonstrate greater difficulties with turns, it raises questions about how sensitive MPS are to turns and falls. We examined the effect of the presence of MPS on gait measurements during walking turns and whether there is a moderating effect of MPS on turns relative to straight walking. Participants in this study were non-demented older adults ( n = 346, mean age = 76.21 +/- 6.68, female = 55%) who attended two study visits and had valid gait measurements. They were asked to complete: 1) a walking protocol (i.e., walk three loops), 2) full neuropsychological assessment, and 3) a neurological examination. Gait measurements were acquired from an instrumented walkway. Linear regressions were used to examine associations between MPS and gait measurements (i.e., velocity, stride length, double support percentage) for each walk condition. Linear mixed effects models were run to determine the moderating effect of MPS on gait measurements for straights versus turns (i.e., walk condition) which served as the repeated measures. MPS status / severity served as the between-subject factor, and gait measurements (i.e., velocity, stride length, double support percentage) served as the dependent variables. The interaction between MPS status / severity and walk condition was included in each model to evaluate if MPS had a greater effect on gait measurements during turns compared to straights. Results revealed that MPS presence / severity significantly predicted gait performance in straights and turns, where individuals with MPS performed worse on all studied gait measurements compared to controls. Further, MPS presence / severity moderated the change in double support percentage from straights to turns suggesting a necessary increase in double support by those with MPS relative to healthy controls in order to successfully turn. Additionally, bradykinesia, rigidity, and postural instability / gait disturbance (PIGD) presence moderated the change in double support percentage from straights to turns such that the increase in double support was significantly greater for individuals with these symptoms. Overall, these results suggests that individuals with MPS demonstrate greater difficulty making turns compared to healthy controls, and therefore may be more susceptible to falls given the increased double support percentage during turns.