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Background: Freezing of gait (FOG) in Parkinson’s disease (PD) has been shown to be more frequent in stressful situations, implicating anxiety. Heart rate (HR) has been shown to increase prior to a FOG episode supporting the notion that elevated stress levels may trigger FOG. However, no studies to date have investigated whether elevated HR precedes all subtypes of FOG or only those episodes that are driven by anxiety. Objective: The present study sought to investigate whether 1) HR increases prior to FOG episodes in nonspecific environments (Experiment 1), and if 2) HR increases prior to FOG when provoked in high but not low threat environments using a virtual reality paradigm (Experiment 2). Methods: In Experiment 1, 10 of 19 participants with PD and FOG (PD + FOG) experienced FOG during a series of walking trials. In Experiment 2, 12 of 23 participants with PD + FOG experienced FOG while walking across an elevated and ground level narrow plank in virtual reality. HR was collected throughout the duration of both experiments, while FOG was quantified by experts using video review and tagging. Results: HR significantly increased 2–3 seconds prior to a FOG episode during Experiment 1. In Experiment 2, HR significantly increased 4–6 seconds prior to a FOG episode, specifically while navigating the elevated plank. However, there were no significant increases in HR prior to FOG episodes when participants navigated the ground plank. Conclusion: This study extends previous work further demonstrating that increases in HR prior to FOG episodes appear linked to elevated anxiety levels.

Background: Although prior research has established that freezing of gait (FOG) in Parkinson’s disease (PD) is associated with anxiety, only one study to date has directly manipulated anxiety levels to induce FOG. Objective: The current study aimed to replicate these previous findings and evaluate whether a seated version of a ‘threat’ virtual reality (VR) paradigm could induce anxiety and provoke FOG. Methods: Twenty-four PD patients with FOG were assessed across various threat conditions in both a walking VR paradigm (Experiment 1) and a seated VR paradigm (Experiment 2). Both paradigms manipulated the height (i.e., elevated vs ground) and width (wide vs narrow) of the planks participants were instructed to walk across. Results: Across both experiments, the Elevated + Narrow condition provoked significantly greater number of freezing episodes compared to all other conditions. Higher levels of self-reported anxiety were reported during the Elevated+Narrow condition compared to all other conditions in Experiment 1, and compared to the Ground condition in Experiment 2. Conclusion: These findings confirm that anxiety contributes to FOG and validates the use of a seated VR threat paradigm for provoking anxiety-related freezing. This enables future studies to combine this paradigm with functional MRI to explore the neural correlates underlying the role of anxiety in FOG.