Diseases are sometimes extremely devastating and cruel. Some diseases move very rapidly while others are slow and painful. Treatments are sometimes useful yet other times nothing can stop the silent beasts that lurk in the body. Parkinson's disease is a slow moving disease that slowly corrupts the brain. Parkinson's disease (PD) is a chronic motor disorder that causes tremors, rigidity, slowed body movements, unstable posture and abnormal gait. This happens when neurons, nerve cells, in a part or the brain called the substantial nigra gradually die. These cells normally produce dopamine, a chemical that helps relay messages between areas of the brain that control body movement. The death of the cells leads to abnormal low levels of dopamine, and causes difficulty in controlling muscle tension and muscle movement both at rest and during periods of activity. Parkinson's Disease affects about 500,000 Americans, with about 50,000 new cases diagnosed each year. It is generally a disease that affects people of late or middle age, usually around 60 years of age. However, about 5 percent of patients have early-onset Parkinson's Disease and are younger than 40 years old when symptoms begin. Parkinson's is slightly more common in men than women. So far, scientists have not determined the reason why some people develop this disease and others do not. Some experts blame a process called oxidation. During oxidation, unstable molecules that are produced in the brain, ultimately damage the brain. Another theory suggests that the toxic effects of drugs may cause Parkinson's. Additional evidence suggests that the disease may be related to environmental toxins since some claim that they have found rates of Parkinson's higher in rural areas where farming is intense and residents drink well water. Parkinson's usually begins as a slight tremor of a hand, arm, or leg. The tremors usually affect a limb at rest, but it also may occur when it is in use.