Is it reliable to assess visual attention of drivers affected by Parkinson's disease from the backseat?-a simulator study

Quantifying saccades while walking: validity of a novel velocity-based algorithm for mobile eye tracking

We validate a novel algorithm to detect saccades from raw data obtained during walking from a mobile infra-red eye-tracking device. The algorithm was based on a velocity threshold detection method, which excluded artefacts such as blinks and flickers using specific criteria. Mobile infra-red eye-tracking was performed with a group of healthy older adults (n=5) and Parkinson's disease (n=5) subjects. Saccades determined from raw eye tracker data obtained during walking using the algorithm were compared to a ground truth dataset defined as frame-by-frame visual inspection of raw eye-tracking videos. 100 trials from 10 subjects were analyzed and compared. The algorithm was highly reliable when compared to the ground truth (ICC(2,1) = 0.94), with an overall correct saccade detection percentage of 85%. This provides a simple yet robust algorithm for the analysis of mobile eye-tracking data.

A protocol to examine vision and gait in Parkinson's disease: impact of cognition and response to visual cues

Background

Cognitive and visual impairments are common in Parkinson’s disease (PD) and contribute to gait deficit and falls. To date, cognition and vision in gait in PD have been assessed separately. Impact of both functions (which we term ‘visuo-cognition’) on gait however is likely interactive and can be tested using visual sampling (specifically saccadic eye movements) to provide an online behavioural measure of performance. Although experiments using static paradigms show saccadic impairment in PD, few studies have quantified visual sampling during dynamic motor tasks such as gait.

This article describes a protocol developed for testing visuo-cognition during gait in order to examine the: 1) independent roles of cognition and vision in gait in PD, 2) interaction between both functions, and 3) role of visuo-cognition in gait in PD.

Methods

Two groups of older adults (≥50 years old) were recruited; non-demented people with PD (n=60) and age-matched controls (n=40). Participants attended one session and a sub-group (n=25) attended two further sessions in order to establish mobile eye-tracker reliability. Participants walked in a gait laboratory under different attentional (single and dual task), environmental (walk straight, through a door and turning), and cueing (no visual cues and visual cues) conditions. Visual sampling was recorded using synchronised mobile eye-tracker and electrooculography systems, and gait was measured using 3D motion analysis.

Discussion

This exploratory study examined visuo-cognitive processes and their impact on gait in PD. Improved understanding of the influence of cognitive and visual functions on visual sampling during gait and gait in PD will assist in development of interventions to improve gait and reduce falls risk. This study will also help establish robust mobile eye-tracking methods in older adults and people with PD.

Post-stroke driving: examining the effect of executive dysfunction

INTRODUCTION

Executive dysfunction can refer to both neurocognitive deficits and behavioral symptoms that include impaired judgment, slow decision making, disorganization, impulsiveness, and risk-taking behaviors. Executive dysfunction is relatively common in the post-stroke population but is often undetected. The impact of executive dysfunction on post-stroke driving is unclear but it may pose a risk to affected drivers and other road users.

AIM

The aim of this study was to investigate the relationship between executive functioning following stroke and driving performance.

METHODOLOGY

A case-control study design was used. Purposive sampling was used to recruit stroke participants (n=19) and healthy controls (n=22). Participants were screened using a battery of psychometric assessments including the Montreal Cognitive Assessment and the Benton Judgment of Line Orientation. Driving performance was assessed using the STISIM driving simulator. Executive function was assessed using the Behavioural Assessment of the Dysexecutive Syndrome (BADS) and the Trail Making Test Part B.

RESULTS

The control participants performed better than the stroke participants on the driving assessment and psychometric assessments. There was an association between the scores of the Trail Making Test Part B (Rho=0.34, p=0.034) and the Key Search Test of the BADS (Rho=-0.61, p=0.005), and the driving assessment scores. However, there was no association between the overall BADS scores and the driving assessment scores of the stroke participants.

CONCLUSIONS

The stroke participants underperformed in the driving assessment and the psychometric assessments that detected neurocognitive deficits, which included executive function. The Trail Making Test Part B and Key Search Test of the BADS were related to identify participants' deterioration in driving performance. Practical Applications: In clinical practice, the latter could be used as an indication of a post-stroke driver's performance.