A Randomized Double-Blind Active-Controlled Crossover Trial of Respiratory-Gated Versus Non-Gated Transcutaneous Auricular Vagus Nerve Stimulation for the Treatment of Motor and Non-Motor Symptoms in Parkinson's Disease

This study employs a three-cycle crossover design to compare the effects of three different modes and frequencies of transcutaneous auricular vagus nerve stimulation (taVNS). The interventions include: 25 Hz non-expiratory gated taVNS, 25 Hz expiratory gated taVNS, and 100 Hz expiratory gated taVNS. Participants will be randomly assigned to one of three groups, with each group receiving a different intervention during each cycle, lasting 2 weeks per cycle. A 2-month washout period will be implemented between cycles to eliminate any carryover effects.The study design will include neuropsychological assessments, imaging, eye-tracking data collection, and biological specimen collection before and after each intervention.