The Role of the Noradrenergic System in the Nonmotor Symptoms of Parkinson's Disease

The goal of this clinical trial is to learn about the role of noradrenergic system in the non-motor symptoms of Parkinson's disease. The main objectives it aims to answer are: 1. To explore the association between orthostatic hypertension which is low blood pressure that occurs after going from lying to standing, and several neuropsychiatric and neurocognitive nonmotor features of Parkinson's disease (PD), such as feeling tired or disinterested and depression. 2. To explore the association between central noradrenergic dysfunction, orthostatic hypertension, and nonmotor symptoms of PD by measuring hormonal response to head up tilt-table testing before and after administration of yohimbine. 3. To explore the association between central noradrenergic dysfunction, orthostatic hypertension, and nonmotor symptoms of PD by measuring participants pupils before and after administration of yohimbine Participants will be asked to come onsite for two study visits. Visit one will consist of: * Discussing and signing the Informed Consent Form * Discussing Medical History and Current Medications * Collecting Blood samples * Measuring heart rate and blood pressure * Mental health screening and neurocognitive questionnaires * Pupil test * Test to feel vibrations Visit two will consist of : * Mental Health questionnaire * IV Placement * Blood Draws * Administration of Yohimbine hydrochloride * Head up tilt table * Measuring heart rate and blood pressure * Answering questions about anxiety, mood, and fatigue using a scale * Pupil tests Visit three will be a follow-up call from the Nurse Coordinator to discuss any adverse events.