Intravenous Plasma Treatment for Parkinson's Disease

Inclusion Criteria: * Diagnosis of Parkinson's disease * Disease duration of 1 to 5 years * Willingness to confirm the use of adequate birth control while on the trial will be required in premenopausal women without evidence for an inability to become pregnant. * Willingness to not start any other treatment for Parkinson's or Multiple Sclerosis during the parallel part of the trial. Exclusion Criteria: * Other significant disease, which in the view of the study doctor may make assessment of the efficacy of yFFP difficult. * Unstable medical conditions. * Must weigh at least 45.5 kg. Cannot weigh more than 130 kg. * A severe disease state diagnosis * Litigation. Patients in litigation will be excluded only if conclusion of that litigation is imminent during the course of the study. * If patient is pregnant or breastfeeding. * Complete IgA deficiency. * Rare contraindications to yFFP therapy as per summary of product characteristics. * Receiving yFFP for other reasons. * Ongoing drug or alcohol abuse. * Psychiatric disorder that could, in the judgement of the site investigator, interfere with successful study participation. * Unwillingness or inability to complete the study or an inability to understand the questionnaires being used. * Cancer other than basal cell carcinoma within the last 5 years. However, those patients who have received definitive treatment, such as curative surgery more than 6 months ago, with no known recurrence can be included. * A history of hypercoagulable or thrombophilic clotting abnormalities. * A history of thromboembolic events: ischaemic stroke, confirmed myocardial infarction, pulmonary embolism; deep venous thrombosis except where immobility related (for example, after injury or operation). * Unstable angina pectoris. * Medications that might react with yFFP such as blood thinners * Renal failure or serum creatinine greater than 1.5 times the upper limit of normal at screening. * Any medical condition that, in the opinion of the investigator, would make it unsafe for the patient to participate or which would interfere with assessment of the outcome measures. * Participation in another interventional trial within 3 months of randomization. Participation in non-interventional studies is not a reason for exclusion.