Cardiac Changes in Early Parkinson's Disease: a Follow Up Study

Primary procedures in this study are MIBG scan, DAT scan, NM-MRI, and carvedilol titration. Subjects will return for research visits and imaging every six months for three years. The investigators hypothesize that the rate of decline in DAT scan123I-Ioflupane uptake will be slower in subjects who have received the adrenergic blocker carvedilol, resulting in a decreased clinical phenoconversion rate to parkinsonism.