Clinical Laboratory Evaluation of Chronic Autonomic Failure

* INCLUSION CRITIERIA: Inclusion Critieria: Patients referred for orthostatic hypotension. This is the main subject cohort. * Previously studied and diagnosed with one of the forms of nOH or else newly accrued with a referral diagnosis of orthostatic hypotension, and * 18 years or older, and * Able to provide own consent to participate or have an existing Legally Authorized Representative (LAR). If a patient has already been diagnosed as having neurodegenerative CAF under NIH Clinical Protocol 03-N-0004, this satisfies the inclusion criteria for that patient. Previous enrollment in NIH Clinical Protocol 03-N-0004 is not required for enrollment in this study. We do plan to recruit participation into this study from NIH Clinical Protocol 03-N-0004, which has been closed. If a patient has been referred for OH, then the patient gives consent at the NIH Clinical Center (and therefore is accrued) and then has screening testing at the NIH Clinical Center to confirm that the OH is neurogenic. We anticipate that all patients referred for OH will be shown to have nOH upon screening testing at the NIH Clinical Center. At the time of screening, exclusionary abnormal laboratory test results (e.g., high serum creatinine indicating renal failure) may come to light, in which case they will be withdrawn from the study; however, the patient would have been accrued. Inclusion criteria: Control patients with iatrogenic CAF * Patients with heart transplants or pre- or post-bilateral endoscopic thoracic sympathectomies, and * 18 years or older, and * Able to provide own consent to participate. Inclusion criteria: Control patients with PD No OH: * Patients with PD and no OH who have (a) already been evaluated under other protocols of the AMS and are undergoing follow-up; (b) have already been evaluated under another intramural NINDS protocol; or (c) have cardiac symptoms, signs, or laboratory findings that in the opinion of the PI make it likely there is a cardiac sympathetic lesion, and * 18 years or older, and * Able to provide own consent to participate. Inclusion criteria: Healthy Volunteers: * Age 18 years or older, and * Able to provide own consent to participate. NIH employees may participate. There is no direct solicitation of employees/staff by supervisors. Co-workers will not solicit co-workers. NIH employees are required to abide by NIH Policy Manual 2300-630-3, "Leave Policy for NIH Employees Participating in NIH Medical Research Studies." EXCLUSION CRITIERIA: Patient Group Referred for Orthostatic Hypotension * A medical condition that in the judgment of the Principal Investigator would place the subject at substantially increased acute medical risk, or * A disqualifying condition such as: hepatic or renal failure, symptomatic congestive heart failure, severe anemia, psychosis, refractory ventricular arrhythmias, currently symptomatic coronary heart disease, cerebrovascular disease with current symptoms (e.g., recent transient ischemic attacks), diabetes, or * Secondary form of CAF, such as diabetic autonomic neuropathy, or * Being treated currently (within 2 weeks of anticipated protocol participation) with a medication known to interfere with the cell membrane norepinephrine transporter, which would obviate obtaining scientifically valid results (e.g., tricyclic antidepressant). * Condition that may cause difficulty or inability to insert a catheter into a vein, or * Unable to tolerate lying still for up to 1 hour during the procedures, or * Refusal to undergo certain procedures. These include: (1) IV catheter and blood drawing; (2) DNA extraction, storage, and analysis; (3) PET scanning; or * Unable to travel safely to the NIH CC, or * Lacking consent capacity, unless a Durable Power of Attorney (DPA) is in place, or * Pregnant or breast feeding, or * Subordinates of study investigators or relatives of the PI or AIs. Patient Control Group with Iatrogenic CAF or PD No OH * A medical condition which in the judgment of the Principal Investigator would place the subject at substantially increased acute medical risk, or * A disqualifying condition such as: hepatic or renal failure, symptomatic congestive heart failure, severe anemia, psychosis, refractory ventricular arrhythmias, currently symptomatic coronary heart disease, cerebrovascular disease with current symptoms (e.g., recent transient ischemic attacks), or diabetes, or * Being treated currently (within 2 weeks of anticipated protocol participation) with a medication that would obviate obtaining scientifically valid results (e.g., tricyclic antidepressant). * Condition that may cause difficulty or inability to insert a catheter into a vein, or * Unable to tolerate lying still for up to 1 hour during the procedures, or * Refusal to undergo certain procedures. These include: (1) IV catheter and (2) PET scanning, or * Unable to travel safely to the NIH CC, or * Lacking consent capacity, or * Pregnant or breast feeding, or * Subordinates of study investigators or relatives of the PI or AIs. Healthy Volunteer Group * A medical condition which in the judgment of the Principal Investigator would place the subject at substantially increased acute medical risk, or * A disqualifying condition such as: hepatic or renal failure, symptomatic congestive heart failure, severe anemia, psychosis, refractory ventricular arrhythmias, currently symptomatic coronary heart disease, cerebrovascular disease with current symptoms (e.g., recent transient ischemic attacks), diabetes, or * Being treated currently (within 2 weeks of anticipated protocol participation) with a medication that would obviate obtaining scientifically valid results (e.g., tricyclic antidepressant). * Condition that may cause difficulty or inability to insert a catheter into a vein, or * Unable to tolerate lying still for up to 1 hour during the procedures, or * Refusal to undergo certain procedures. These include: (1) IV catheter and (2) PET scanning, or * Unable to travel safely to the NIH CC, or * Lacking consent capacity, or * Pregnant or breast feeding, or * Subordinates of study investigators or relatives of the PI or AIs.