Distinct finger-tapping feature in progressive supranuclear palsy correlates with motor function and brain atrophy.

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disorder characterized by 4-repeat tau deposition, whose symptoms overlap with Parkinson's disease (PD). It is necessary to develop objective biomarkers for accurate differentiation. This study used video-based kinematic analysis to assess finger-tapping performance in 31 PSP patients, 31 PD patients, and 30 healthy controls (HC). Results showed PSP patients exhibited smaller finger-tapping angles, slower velocities, shorter cycle durations, and no sequence effect compared with PD patients and HCs. The average finger-tapping angle effectively distinguished PSP from PD (AUC = 0.83). In PSP, smaller angles and velocities correlated with worse motor and balance function, and these finger tapping parameters were associated with volumes of nucleus accumbens, superior temporal gyrus, cerebellum, and brainstem. Video-based finger-tapping kinematic analysis serves as a non-invasive biomarker for PSP diagnosis and motor assessment.