Girlea, Alexandra Laura2025-12-172025-12-172025-12-172025-12-15https://hdl.handle.net/10012/22758Functional Gait Disorders (FGD) are a subgroup of Functional Neurological Disorders (FND) that are characterized by the presence of abnormal postures and movements whose appearance and severity fluctuate, or are inconsistent, over time. These movements appear voluntary but are reported to be involuntary by the patient. FGD symptoms may arise from abnormalities in attentional and emotional regulation, and these dysfunctions lead to loss of agency (control) over movement. These movements may mimic those of other neurological disorders, however sensory and motor testing reveals normal function. This preservation of function despite symptom presentation is referred to as symptom incongruency. Due to the inconsistency and incongruency FGD symptoms, as well as the heterogeneity in phenomenology across individuals with FGD, diagnosis proves a challenge. Individuals with FGD often face delays and excessive costs when pursuing an appropriate diagnosis, ultimately prolonging their disability and delaying access to adequate treatment. A majority of previous work has utilized qualitative approaches to phenotype FGD and aid in diagnosis. While these approaches provided key foundational information about FGD, they do not capture all aspects of FGD. Therefore, quantitative methods of FGD may provide more insight into its phenomenology. However, there is a lack of work utilizing quantitative approaches in FGD. Existing work has primarily focused on the influence of attentional distraction on symptom presentation and severity during gait, providing mixed evidence addressing the influence of attention on functional gait. Similar to qualitative descriptions, some quantitative evidence shows an improvement in symptom presentation and severity while completing a secondary task. To date, there have been no studies investigating the effect of emotional distress on gait in FGD, and this area would be important to investigate given that emotional dysregulation is a key component of FGD phenomenology. While anxiety during gait has been manipulated with postural threat paradigms, the threat of shock paradigm has also been shown to elicit anxiety in laboratory settings. However, the threat of shock has not yet been utilized in gait research. Investigating its validity for use in gait may provide more insight into how this paradigm provokes anxiety during walking, and how walking may change during this scenario. As such, the present thesis aims to address several gaps in the literature. The first is that there are few quantitative descriptors of FGD phenomenology, therefore identifying descriptors may complement and augment qualitative observation and subsequent diagnosis. The second is that while the influence of attention has been investigated in FGD, there has been limited work done investigating the influence of emotional distress on gait in this population, despite its self-reported influence on symptom provocation. Understanding or characterizing the influence of emotional distress on gait in this group may provide novel insights for clinical diagnosis. The use of the novel threat of shock paradigm may also provide more insight into the influence of anxiety on walking in FGD. Together, the present study aimed to address these gaps by utilizing the novel threat of shock paradigm to investigate the influence of attentional distraction and emotional distress on gait behavior and symptom severity in individuals with FGD. It was expected that the threat of shock paradigm would elicit anxiety in all participants. Additionally, it was expected that the dual task would lead to normalized gait in the FGD group, and that the threat of shock would yield a worsening of gait in the FGD group. Finally, it was anticipated that greater levels of movement reinvestment in FGD patients would be associated with a greater dual-task effect on gait in this group, meaning that greater reinvesters would show a greater degree of movement normalization when completing a dual task compared to walking in the absence of a dual task. Eleven FGD patients and 17 age- and sex-matched controls completed 11 walking trials that spanned 4 conditions (neutral, dual task, shock, dual task + shock). All participants self-reported their level of anxiety after each trial, and at the end of the study, completed a battery of questionnaires addressing their movement reinvestment and anxious tendencies. The present study confirmed the utility of the threat of shock during gait, as participants reported greater anxiety when the shock was present. Interestingly, the dual task did not lead to gait normalization in FGD patients. Rather, both patients and matched controls showed worsened gait in the presence of the dual task. Additionally, the threat of shock only impacted step length variability in FGD patients, wherein patients showed greater variability compared to controls in both the presence and absence of shock. Finally, the present study revealed insights into the relationship between reinvestment and symptomology in FGD, wherein patients with a greater degree of reinvestment showed improved gait while dual tasking compared to their baseline gait. Taken together, the present study not only illustrates the utility of the threat of shock paradigm in gait assessments, but also shows nuances in the relationship between attentional distraction and FGD symptomology. Findings from the present study set the stage for future use of the threat of shock during gait, as well point to the importance of movement reinvestment in the presentation and potential resolution of symptoms in FGD. Future work should continue to investigate reinvestment in the context of FGD and should take a more nuanced and individualistic approach to better encapsulate the heterogeneity inherent in functional gait disorders. Doing so may provide a more complete picture of these disorders and may improve characterization, diagnosis, and treatment of these patients.enfunctional gait disordersattentionanxietyMaster Thesis