Video-based kinematic analysis of finger tapping distinguishes PSP from PD (AUC=0.83), with smaller angles and slower velocities correlating with worse motor/balance function and with atrophy in nucleus accumbens, superior temporal gyrus, cerebellum, and brainstem.

As a non-invasive, quantitative biomarker for differential diagnosis and motor monitoring in parkinsonian syndromes, this method can improve patient selection and outcome measurement in trials, though it does not directly reveal PD therapeutic targets or mechanisms.

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.