Scaling Cues to Freeze Gait: An Augmented Reality Approach to Benchmark Freezing of Gait in Parkinson's Disease

BackgroundFreezing of gait (FOG) affects up to 80% of people with advanced Parkinsons disease and is difficult to elicit reliably during clinical assessments. Augmented reality (AR) offers potential for standardized FOG provocation by presenting virtual triggers in any environment. ObjectiveTo evaluate whether an AR-based turning task could elicit FOG in a graded, dose-dependent manner and assess user experience with the technology. MethodsThirteen people with Parkinsons disease (8 freezers, 5 non-freezers) completed an AR pillar-turning protocol across two cohorts: clinic-based (n=4, all freezers) and laboratory-based (n=9, mixed). Participants performed 360{degrees} turns around a virtual pillar presented at three diameters (0.6, 0.4, 0.2 m) using a Microsoft HoloLens 2, manipulating turning radius to vary task difficulty. FOG episodes were video-recorded and independently annotated. Participants completed perception questionnaires and the New Freezing of Gait Questionnaire (NFOG-Q). ResultsAll clinic freezers exhibited FOG during AR pillar turns, with a clear dose-response relationship: mean episodes increased from 2.3 at 0.6 m to 5.3 at 0.4 m to 8.5 at 0.2 m diameter. No laboratory participants experienced FOG during pillar turns, though one lab freezer froze during return turns. NFOG-Q profiles indicated comparable daily-life FOG severity between clinic and laboratory freezers, suggesting environmental factors drove differential outcomes. Participants reported positive experiences with AR quality, safety, naturalness of movement, and rapid adaptation, though clinic participants reported higher immersion than laboratory participants. ConclusionsAR-based pillar-turning successfully elicited graded FOG in susceptible individuals within a FOG-provoking environment, demonstrating proof-of-concept for scalable virtual trigger paradigms. Effectiveness depends on matching environmental context to individual FOG susceptibility, with implications for standardized clinical FOG assessment.