Digital Handwriting Reveals Motor Impairment, Dopaminergic Response, and Progression in Parkinson's Disease

BACKGROUND: Digital handwriting distinguishes PD patients from healthy controls but is rarely assessed quantitatively. OBJECTIVES: To evaluate digital handwriting as an objective tool to assess motor impairment, dopaminergic response, and progression in PD. METHODS: Participants (Healthy Controls, n = 52; De Novo PD Patients assessed at baseline and after 7 weeks, n = 50; PD Patients in OFF-ON states following inhaled levodopa, n = 26; PD Progression Patients, n = 60) wrote a standard sentence on a digitizing tablet. RESULTS: De Novo PD Patients showed reduced handwriting speed and increased in-air time. Acute dopaminergic stimulation in OFF-ON states was associated with shorter in-surface and in-air time. Longer disease duration was associated with increased variability in speed and acceleration. Higher MDS-UPDRS Part III scores were associated with lower speed and acceleration. CONCLUSIONS: Digital handwriting is an objective digital biomarker for quantifying PD dysgraphia and its response to dopaminergic treatment.