Parkinson's Disease is a brain disorder that causes tremors and difficulty with movement and walking, and most commonly affects people over the age of 50. Allison W. Willis, from Washington University (Missouri, USA), and colleagues found that of nearly 140,000 Medicare beneficiaries with Parkinson's disease diagnosed in 2002 – about half of whom were younger than 80 years –  64% had died by 2008.  This rate was similar to that seen in Medicare patients suffering myocardial infarctions and Alzheimer's Disease, and substantially higher than in those diagnosed with congestive heart failure, chronic obstructive pulmonary disease (COPD), or colorectal cancer.  The incidence of dementia was common and markedly increased the risk of death in Parkinson's Disease, whereas women, Hispanics, and individuals of Asian ancestry were at lower risk of death during the study period.  Geography did not appear to affect mortality in Parkinson's Disease patients with one exception -- those living in urban areas known to have high levels of industrial manganese pollution were at almost 20% higher risk of death than those in low-pollution areas; however, there was no difference in death rates between areas of high and low lead pollution.  Writing that: “Demographic and clinical factors impact [Parkinson's Disease] survival,” the study authors urge for: “More research is needed to understand whether environmental exposures influence [Parkinson's Disease] course or survival.”