Respiratory-gated Transcutaneous Auricular Vagus Nerve Stimulation for Improving Apathy in Parkinson's Disease

The goal of this clinical trial is to learn whether 100HZ respiratory-gated vagus nerve stimulation (RAVANS) can improve the non-motor symptoms in people with Parkinson\'s disease (PD). It will also learn the safety of 100HZ RAVANS. The main questions it aims to answer are: Can 100HZ RAVANS improve apathy in people with PD? Did the participants have any side effects or safety issues when undergoing 100HZ RAVANS? Researchers compared 100HZ RAVANS with sham stimulation (low-dose stimulation of the same site and treatment parameters) to see if 100HZ RAVANS could improve non-motor symptoms in patients with PD. Participants will: Receive 100HZ RAVANS or sham stimulation for 2 weeks. Neuropsychological assessment, imaging and biological sample collection were conducted before and after the entire cycle.