Patients with Parkinson’s disease (PD) suffer from interrelated motor and non-motor symptoms. While most research focuses on motor improvement, this study investigated whether targeting mood via sequential bilateral dorsolateral prefrontal cortex (DLPFC) tDCS could favorably affect motor function in patients maintaining a stable medication ‘ON’ state. Additionally, we employed wearable smart devices to objectively evaluate real-world changes in daily activity and sleep patterns, complementing traditional clinician-rated scales.

PD patients with mild-to-moderate depressive symptoms were enrolled. All participants completed a 7-day baseline monitoring period using a smart band. Participants received ten sessions of bilateral tDCS targeting the DLPFC (anode F3, cathode F4) at 2 mA for 30 minutes, three times a week. Clinical assessments and smart band monitoring were repeated during the final week of treatment. Pre–post changes and correlations were analyzed while controlling for potential confounders.

Following tDCS, it was significant improvements in K-MADRS, STAI, AS, UPDRS part III, and PDQ-39. Smart device data showed a significant increase in daily step counts after treatment, while changes in physical activity time and sleep duration were not significant. Changes in step count were strongly correlated with improvements in apathy, and this relationship remained significant after confounding variables (rho = –0.76, p < 0.001).

Bilateral DLPFC tDCS significantly improved mood and motor function in patients with PD. Smart band data further showed an increase in daily step counts after the intervention, with reductions in apathy. These findings suggest that tDCS may enhance goal-directed behavior by modulating mood-related pathways, highlighting apathy as an important therapeutic target in PD.