Semantic Fluency Predicts Gait Velocity in PSP

Progressive supranuclear palsy (PSP) is a large-scale network disease resulting in variable signs and symptoms including gait impairment and higher order cognitive dysfunction. Despite few studies showing the association of falls and cognitive dysfunction, the existing literature is yet to establish the exact relationship of discrete characteristics of gait with cognitive function in PSP.

In this cross-sectional study, we aimed to characterize and explore the relationship of these two apparently distinct physiological phenomena in patients with PSP and across its different variants.

Quantitative assessment of two-dimensional gait parameters was measured using an electronic walkway (GAITRite®). Dementia Rating Scale-2 was used to assess global as well as higher order cognitive functions.

A regression model was used to interpret results.

We observed that the variability domain of gait was significantly impaired in PSP patients with severe cognitive impairment compared to that of intact cognition. Moreover, initiation/perseveration (I/P), a higher order cognitive process, and one of its specific components, i.e., complex verbal task (β = 2.39, P < 0.001), significantly predict gait velocity in PSP [F (1, 40) = 16.102, P < 0.001].

Our findings indicate that the severity of cognitive functions affects gait variability, which might lead to frequent falls as observed in PSP. Furthermore, semantic fluency task of I/P function may act as a predictor of gait velocity. We suspect that higher order cognitive dysfunction through the damage of frontal lobe structure including dorsolateral prefrontal cortex or related network may influence gait in PSP.