Clinical Study of Chemogenetic Gene Therapy With AAV for Parkinson's Disease Using Stereotactic Surgery in the Subthalamic Nucleus

Inclusion Criteria: * Age range: 40 - 70 years (inclusive), gender not restricted; * Diagnosed with primary Parkinson's disease, with H\&Y grade ranging from 4 to 5; * Disease duration of at least 5 years; * Response to levodopa treatment lasting for at least 12 months; * Score of the third part of the MDS-UPDRS Part III ≥ 35; * Improvement rate of the Madopar challenge test ≥ 30%; * Stable clinical symptoms and drug treatment for at least 4 weeks before screening; * Capable of understanding and voluntarily signing the informed consent form; * Participants agree to postpone any neurological surgery, including deep brain stimulation, until the completion of 12-month follow-up; * The efficacy of dopamine drugs has significantly decreased, or there are obvious motor complications, or severe drug side effects; * There are no acute adverse reactions to the prescribed olanzapine dose; * Good compliance and willing to complete all the follow-up as stipulated in this protocol. Exclusion Criteria: * Has a past history of brain surgery for Parkinson's disease, such as deep brain stimulation, or other abnormal brain imaging findings; * Hamilton Depression Scale score ≥ 20; * Hamilton Anxiety Scale score ≥ 14 * Has a history of brain injury or central nervous system infection; * MoCA cognitive impairment score \< 26 points, and MMSE dementia rating scale cognitive impairment score ≤ 20 points; * Focal neurological deficits; * Evidence of major medical or mental illness, such as dement…