Study to Evaluate SYN115 in Parkinson's Disease

Inclusion Criteria: * Diagnosis of Parkinson's disease * Hoen and Yahr stage 1-3 * On stable dose of anti-parkinsons treatment for 30 days prior to screening * Age 40 to 75 years * Sign an IRB approved informed consent * Men and women agree to use adequate birth control * ECG measurements are within normal limits * Able to understand study requirements Exclusion Criteria: * Secondary Parkinson's (drug induced or post stroke) * Received treatment with other investigational drug 30 days prior to study entry * Using disallowed medications * Significant neurological illness other than Parkinson's * IQ less than 70 on IQ test * MMSE score \< or = 23 * History of psychosis or on anti-psychotic medication * Current serious medical illness * History of substance abuse * History of head injury with loss of consciousness * History of brain surgery * Contraindications to MRI like claustrophobia, metal implants or other implantable devices * Abnormal liver function tests and/or hepatitis or cholangitis * Gilberts disease * Pregnant or nursing * Known hypersensitivity to SYN115