Feasibility Of Objective Measures and Outpatient Washout in Disease Modifying Trials for Parkinson's Disease

Inclusion criteria

• *A clinical diagnosis of idiopathic PD. The diagnosis will be based upon the presence of at least two of the three cardinal motor signs of this disorder (akinesia/bradykinesia, rest tremor, and rigidity) with at least one of the signs being rest tremor or bradykinesia.
• Clear and dramatic beneficial response to dopaminergic therapy (defined as demonstrating at least 30% improvement in parkinsonian motor signs based upon the UPDRS-III motor examination subscore, following the administration of their dopaminergic medications during the screening neurological examination)
• *Hoehn and Yahr (H&Y) stage II when off medication.
• Age between 50 and 75 years.
• Subjects must be on dopaminergic therapy for at least one year prior to the screening visit and less than four years prior to the completion of the washout period.
• Subjects must have a stable response to dopaminergic medication.
• Available for follow-up for the entire duration of the study.
• Subjects receiving antidepressant medication used specifically for the treatment of depression must be on stable doses for at least eight weeks prior to enrolling in the study.
• Subjects must agree to maintain a stable regimen, if deemed medically appropriate by the treating physician, of any psychotropic medications throughout the study.

Exclusion criteria

• *Evidence of an alternative diagnosis or secondary parkinsonism, as suggested by:

• Features unusual early in the clinical course (e.g., prominent postural instability, freezing phenomena, or hallucinations unrelated to medications in the first 3 years after symptom onset)
• Dementia preceding motor symptoms
• Neurologic signs of upper motor neuron or cerebellar involvement
• Significant orthostatic hypotension unrelated to medications
• Unequivocal cortical sensory loss (i.e., graphesthesia, stereognosis with intact primary sensory modalities), clear limb ideomotor apraxia, or progressive aphasia
• Vertical supranuclear gaze palsy, or selective slowing of vertical saccades
• Unequivocal cerebellar abnormalities on examination, such as cerebellar gait, limb ataxia, or cerebellar oculomotor abnormalities (e.g., sustained gaze-evoked nystagmus, macro square wave jerks, hypermetric saccades)
• Documentation of a condition known to produce parkinsonism and plausibly connected to the subject's symptoms (e.g., history of stroke, exposure to toxins, or encephalitis; or neuroleptic use within the past 6 months)
• *The expert evaluating physician, based on the full diagnostic assessment, believes that an alternative syndrome is more likely than PD.
• *Uncontrolled medical condition or clinically significant medical disease that would increase the risk of developing pre- or postoperative complications (e.g., significant cardiac or pulmonary disease, uncontrolled hypertension).
• *Evidence of existing dyskinesias.
• *Diagnosis of probable behavioral variant frontotemporal dementia or primary progressive aphasia.
• *Currently active diagnosis of a major psychiatric disorder
• Previous brain operation or injury.
• Active participation in another clinical trial for the treatment of PD.
• *Any current substance use disorder.
• Any history of recurrent or unprovoked seizures.
• Any prior movement disorder treatments that involved intracranial surgery or device implantation.
• Any active implanted intracranial device (e.g., cochlear implant) or implanted device to treat movement disorders (e.g., duodopa pump) whether turned on or off.
• History of suicide attempt.
• A female who is breastfeeding or of child-bearing potential with a positive urine pregnancy test or not using adequate contraception.
• Inability or unwillingness of subject to give written informed consent.
• *Parkinsonian features restricted to the lower limbs for more than three years.
• *Treatment with a dopamine receptor blocker or a dopamine-depleting agent in a dose and timecourse consistent with drug-induced parkinsonism.
• Rapid progression of gait impairment requiring regular use of a wheelchair.
• *Early bulbar dysfunction, defined as one of severe dysphonia, dysarthria (speech unintelligible most of the time), or dysphagia [requiring soft food, nasogastric (NG) tube, or gastrostomy feeding].
• *Inspiratory respiratory dysfunction defined as either diurnal or nocturnal inspiratory stridor or frequent inspiratory sighs.
• *Recurrent (>1/year) falls because of impaired balance within 3 years of onset.
• *Otherwise unexplained pyramidal tract signs, defined as pyramidal weakness or clear pathologic hyperreflexia (excluding mild reflex asymmetry in the more affected limb and isolated extensor plantar response).
• *Bilateral symmetric parkinsonism throughout the disease course. The patient or caregiver reports bilateral symptom onset with no side predominance, and no side predominance is observed on objective examination.
• Received radiation exposure as part of other recent research studies and individuals who work around radiation will be excluded from the study
• Subjects who do not pass the neuropsychological screening battery.
• *Subjects who, in the opinion of the study neurologist or principal investigator, should not participate in the study