Istradefylline Effect Protocol on Parkinson's Disease Tremor

In this 6-month open label, single arm, exploratory pilot study, the investigator intends to enroll a pilot sample of 25 patients with Parkinson's disease who are being started on the novel FDA approved medication "Istradefylline'' as an add on therapy for management of their motor symptoms (based on the judgment of the movement disorders specialist, if patients are in suboptimal management of their symptoms on maximum tolerable dose of their dopaminergic medications). The investigator will evaluate their motor symptoms before starting the new medication, including their MDS-UPDRS total and MDS-UPDRS-III scores.

Based on data from an early experience limited data set within our clinical practice of patients taking Istradefylline, the investigator noted improvement in motor symptoms on PDRS-III. The investigator evaluated the degree of tremor with a tremor quantifying software before and after 8 weeks of therapy. Tremor amplitude, frequency and severity improved in the first two patients based on said parameters.

Secondary analysis in week 24 will include all aforementioned assessments. The investigator will compare their score and results before and after the medication.

The therapeutic intervention will consist of evaluating the effect of the addition of Istradefylline 40 mg daily (after two weeks of Istradefylline 20 mg daily) in patients already on levodopa and other anti- parkinsonian treatments. Patients will be screened based on inclusion and exclusion criteria. Enrolled patients will need to be on a stable regimen of all their concomitant medications for at least 30 days prior to baseline visit. All PD concomitant medications are allowable. Participants must also have a MOCA (Montreal Cognitive Assessment) of 22 or greater, and the absence of a diagnosis of dementia.

Tremor score will be clinically defined by the presence of a sum score of at least 8 of 32 of the MDS-UPDRS tremor items 16, 20, and 21 (referred to as tremor score). The generation of this sum score is based on the validity of the MDS-UPDRS regarding tremor, 19 and the clinical experience, that the MDS-UPDRS tremor items reflect different but similarly important aspects of Parkinsonian tremor, including the impairment of activities of daily living by tremor.