PARKINSON'S DISEASE: DETECTING PARKINSON’S DISEASE WHEN IT MIGHT STILL BE CURABLE.A patient with Parkinson’s disease (PD) has to lose 60-70% of the nerve cells in a particular area of the brain before the physical symptoms of PD appear. http://www.parkinsonresearchfoundation.org/resources/information.aspx?post=8cfbb238-b02e-4b80-b938-51d86400ee65