Verbal fluency is associated with Gait impairment in Progressive Supranuclear Palsy

Introduction: Gait impairment is an important diagnostic criterion for Progressive Supranuclear Palsy (PSP) and may be modulated by specific cognitive domains such as executive function. This study aims to investigate the relationship between executive function and gait in PSP, using verbal fluency tasks as a cognitive measure alongside clinical assessments and objective gait analysis with wearable sensors. We explore whether these relationships are sustained longitudinally. Methods: Twenty-six participants with PSP were recruited as part of the Oxford Quantification in Parkinsonism (OxQUIP) study, and 17 of them were followed up longitudinally over five visits at three-month intervals. Clinical symptoms were assessed using the PSPRS and executive function was tested with phonemic (letter F) and semantic (animal names) verbal fluency tasks. Gait characteristics – including speed, stride length, and gait variability – were measured during a two-minute walk task using body-worn sensors. Results: Higher semantic fluency was distinctly linked with lower clinical symptom severity (p = 0.008) and lower variability in gait speed (p = 0.027) and stride length (p = 0.041). The association between semantic fluency and gait speed variability (p = 0.042) was confirmed by the longitudinal analysis. Conclusions: Higher semantic fluency is linked with reduced gait variability (i.e., more controlled movements), and this link persists over time, potentially reflecting a mechanism to prevent falls. Our findings highlight the clinical importance of executive function for gait stability, emphasizing its role in PSP assessment and tau-directed therapies.