50 Hz Repetitive Transcranial Magnetic Stimulation (rTMS) for the Treatment of Parkinson's Disease

Background: * In transcranial magnetic stimulation (TMS), a device creates a short-lasting magnetic field which induces an electric current in the brain leading to a change in the activity of brain cells. There are different effects on the brain with different rates of stimulation. In a previous study in people with Parkinson's disease, repetitive TMS (rTMS) given at a particular rate temporarily improved their ability to walk. A faster rate of rTMS may be more effective in treating symptoms than the rate originally used. * This study will compare active rTMS to inactive (sham or Placebo) rTMS. Half of the people in this study will have active rTMS; the other half will have no brain stimulation with rTMS. Objectives: \- To see if a faster rate of transcranial magnetic stimulation is a more effective treatment for the symptoms of Parkinson's disease than the slower rates that have been studied. Eligibility: * Individuals between 40 and 80 years of age who have been diagnosed with mild or moderate Parkinson's disease. * Participants must currently be taking Sinemet or dopamine agonists drugs (e.g., bromocriptine, cabergoline, pergolide, pramipexole, ropinirole, apomorophine, and rotigotine), and are willing to continue their same treatments for the duration of the study. Design: * This study requires 11 outpatient visits to the NIH Clinical Center over 6 weeks. Participants can also be admitted and stay as an inpatient in the NIH Clinical Center for the entire study period (for the 10 visits during the first weeks and the follow-up visit a month later). * Initial visit will consist of a physical examination; a test of participants' time to walk 10 meters; and questions about memory, mood, and quality of life. Participants should not take Parkinson's disease medications for 12 hours before this visit; once the examinations and tests are complete, participants will be able to take the medications. Researchers will repeat the tests 1 hour after participants take t