Participants will receive baseline testing to confirm a diagnosis of Parkinsonism and to determine eligibility in the research study. Half of the participants in this study will be in a group that will receive the study drug (rasagiline), and half will be in a group that will receive a placebo. A placebo is a pill that is made to look like the study drug, but it does not contain any active ingredients. A computer algorithm will randomly decide group assignment (like the flip of a coin). The study drug will be provided at the end of the first visit. The participants will not know which study drug is received, placebo or rasagiline.