NINDS Parkinson's Disease Neuroprotection Trial of CoQ10 and GPI 1485

Inclusion: * Willing and able to give informed consent. * Men and women with idiopathic PD of less than 5 years duration from diagnosis. * Diagnosis must be confirmed by bradykinesia plus one of the other cardinal signs (resting tremor, rigidity) being present, without any other known or suspected cause of parkinsonism. The clinical signs must be asymmetric. * Subjects must not require any therapy (including levodopa, dopamine agonists, anticholinergics, amantadine, or selegiline) to treat symptoms of PD at the time of enrollment. Subjects may have had prior exposure to any one of these agents, but exposure with any agent may not have been longer than 60 days in duration and subjects must not have been on any of these agents within 90 days prior to baseline. Once a subject needs dopaminergic treatment, these medications may be added as part of best medical management. The subject will still remain in the study. * Age \> 30 years. * Willingness and ability to comply with study requirements. * Women who are not postmenopausal or surgically sterile must use a medically accepted contraceptive regimen for at least 60 days before the baseline visit, and agree to continue such use throughout the duration of the study and for 30 days after the final dose of study drug. Reliable forms of contraception include oral, implanted, or injected contraceptives; intrauterine devices in place for at least 3 months; or adequate barrier methods in conjunction with spermicide (abstinence is considered an acceptable contraceptive regimen). Women must have a pregnancy test unless they are at least 2 years postmenopausal or surgically sterile. Exclusion: * Use of any of the following drugs within 180 days prior to baseline: neuroleptics, metoclopramide, alpha-methyldopa, clozapine, olanzepine, and flunarizine. * Use of any of the following drugs within 90 days prior to baseline: methylphenidate, cinnarizine, reserpine, amphetamine, or MAO-A inhibitors (pargyline, phenelzine, and tranylcypromine). * Presence of atypical Parkinson's syndromes due to drugs (e.g., metoclopramide, flunarazine), metabolic identified neurogenetic disorders (e.g., Wilson's disease), encephalitis, or other degenerative diseases (e.g., progressive supranuclear palsy). * Use of CoQ10 or GPI 1485 90 days prior to baseline. * Use of minocycline or creatine 90 days prior to baseline. * Receipt of other investigational drugs within 90 days prior to baseline. * Presence of freezing. * Impairment of postural reflexes (pull test score \> 0). * Any clinically significant medical condition (e.g., active GI illness, angina, active neoplasm) or laboratory abnormality, which would in the judgment of the investigator interfere with the subjects ability to participate in the study or to be followed. * History of stereotaxic brain surgery for PD (e.g., pallidotomy, deep brain stimulation, fetal tissue implantation). * Clinically significant structural brain disease that the investigator believes would interfere with study evaluations. * Significant psychiatric disorders that may interfere with complying with the protocol. * History of known hypersensitivity or intolerability to CoQ10 or GPI 1485.