›Inclusion and exclusion criteria, as posted
Inclusion Criteria:
* Age \> 18 years.
* Ability to attend a 3 hour study visit in Seattle, WA.
* Ability to read and speak English.
* Have three or more of the required positive criteria for PD from Step 3 of the UK Brain Bank Diagnostic Criteria for Parkinson's Disease.
* A modified Hoehn \& Yahr Stage 2-3. (bilateral disease, not severely disabled.)
Exclusion Criteria:
* Any contra-indication to magnetic resonance imaging, including pacemaker, pacemaker wires, aneurysm clip, or any electronic implant, weight over 136 kg (300 lb), metal embedded in soft tissue or in the eye, prosthetic eye, claustrophobia, substance abuse, use of recreational drugs, pregnancy, or other medical contraindications.
* A history of epilepsy, stroke, brain surgery, or structural brain disease.
* The presence of other serious illnesses (discretion of study clinician, e.g. concurrent cancer treatment.)
* Pregnant.
* A history of sulfur sensitivity, e.g. reaction N-acetylcysteine, MSM, SAMe.
* A recent history of asthma.
* Supplementation with glutathione (oral, intravenous, intranasal, or nebulized) or the glutathione precursor, N-acetylcysteine, for six months prior to baseline study visit.
* History of sensitivity to sulfur containing medications/ supplements, i.e. NAC, MSM.
* Current drug or alcohol use or dependence.
* Inability/unwillingness to provide informed consent. (e.g. diagnosis of dementia, confusion about study goals or participation.)
* Acute infection (e.g. upper respiratory, dermal) in the previous 30 days.
* Diagnosis of any mental illness, ever. (Mental illness has been associated with glutathione depletion.)
* Diagnosis of any chronic disease, ever. (e.g. Hep C, autoimmune disease, etc.)
* Head tremor or head dyskinesia that cannot be comfortably controlled for 90 minutes.