Inclusion Criteria:  Patients with Parkinson's Disease Exist non-motor symptoms Undergoing selective DBS. Age ≥60 years. Obtain written informed consent.  Exclusion Criteria:  Preoperative severe cognitive impairment (Montreal Cognitive Assessment, MoCA< 18). History of psychotropic drugs. Severe bradycardia (heart rate less than 40 beats per minute), sick sinus syndrome or second-to-third degree atrioventricular block. Severe hepatic or renal dysfunction.