Abstract
BACKGROUND: The impact of levodopa on gait in individuals with Parkinson's disease (PD), particularly in those with and without a history of falls, remains unclear. OBJECTIVE: This study examines whether levodopa alters digital gait characteristics in fallers and non-fallers with PD to those observed in healthy controls (HC) and identifies key gait and turning measures most influenced by levodopa. METHODS: We recruited 33 individuals with PD (17 fallers, 16 non-fallers) and 17 HC. Participants wore six inertial sensors on both wrists, feet, lumbar region (L5), and sternum while performing a walking test in Off and On levodopa states. Seventeen digital gait measures were extracted, and responsiveness to levodopa was assessed using standardized response means (SRM). RESULTS: Fallers exhibited greater turning impairments Off levodopa than non-fallers. Levodopa significantly improved nearly all gait measures in both groups, normalizing them to HC levels. It had a strong effect on gait (fallers: highest |SRM| = 1.32; non-fallers: highest |SRM| = 0.94). In fallers, turn velocity, toe-off angle, gait speed, and stride length showed the most improvement (|SRM| >1). Non-fallers showed the greatest improvements in trunk coronal range of motion (ROM), arm swing velocity, arm ROM, and turn velocity (|SRM| >0.8). Fallers had worse patient-reported outcomes and balance test scores, but no significant differences in UPDRS Part III, and Hoehn and Yahr scores. CONCLUSIONS: These findings suggest that impaired turning and gait shuffling in PD may be associated with falls and that dopamine replacement therapy, as well as rehabilitation, focused on improving turning and gait shuffling may reduce fall risk.