Lookup NU author(s): Dr Sam Stuart,
Dr Lisa Alcock,
Dr Brook Galna,
Dr Susan Lord,
Professor Lynn Rochester
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BACKGROUND: Gait impairment is a core feature of Parkinson’s disease (PD) with implications for falls risk. Visual cues improve gait in PD but the underlying mechanisms are unclear. Attentional or visual processes may underpin response to visual cues, and can be studied by measuring visual exploration (saccades and fixations) when walking. For example; visual cues may prompt greater visual exploration to task-relevant locations (e.g. floor) during gait rather than irrelevant locations (e.g. ceiling). Understanding how cueing influences visual exploration will help develop effective therapeutics.This study examined visual exploration in response to a visual cue during gait in PD. We studied; 1) visual exploration under cued and dual-task conditions; and 2) relationship between visual function, attention, visual exploration and gait in PD.METHODS: Visual exploration (saccade frequency (SF), fixation number (FN)) was measured using a mobile eye-tracker in 55 PD and 32 age-matched control participants while walking. Fixation location was examined in a sub-group of 20 PD and 21 controls. Participants walked with and without a visual cue under single and dual-task (forward digit-span). Visual function and attention were also assessed. Changes in visual exploration in response to cues and dual-task were compared with ANOVA or Friedman analysis. Relationships between exploration, visual function, attention and gait were explored using bivariate and structural equation modelling (SEM) analysis.RESULTS: Attention and visual function were significantly impaired in PD. Visual exploration was impaired in people with PD who had greater fixations on unrelated locations during non-cued gait compared to controls. Visual exploration increased with a cue (SF and FN p<.001) and the increase was maintained under dual-task (SF p=.008, FN p=.022) irrespective of group, with greater increase in PD. Both groups increased fixations to task-relevant locations with a cue (p<.001) and people with PD reduced fixations to unrelated locations.Attention rather than vision played a central role in cue response in PD. SEM analysis showed that attention directly related to SF, visual function and cued-gait velocity (ß=-.37, p=.036) in PD, whereas visual function only related indirectly to SF (ß=-.12, p=.008) and cued-gait velocity (ß=-.17, p=.031) with relationships underpinned by attention. Attention also underpinned an indirect relationship between SF (ß=.10, p=.031) and cued-gait velocity in PD.CONCLUSION: Visual cues elicit greater visual exploration of task-relevant locations during gait in PD, with response facilitated through attentional mechanisms. However the specific attentional aspects involved in cue response require further examination.
Author(s): Stuart S, Alcock L, Hunt D, Galna B, Lord S, Rochester L
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: World Congress of the International Society for Posture and Gait Research
Year of Conference: 2017
Print publication date: 29/06/2017
Online publication date: 29/06/2017
Acceptance date: 29/06/2017