Understanding Parkinson's Disease (PD)

Parkinson's disease is a disorder of the central nervous system. The central nervous system includes the brain and spinal cord. Parkinson's disease is one of the conditions known as a movement disorder.

Certain cells in the brain make a chemical substance called dopamine (DOE-puh-mean). Dopamine carries messages that tell the body how and when to move. Parkinson's disease occurs when these brain cells die or are damaged. There is no longer enough dopamine to carry these messages, and movement becomes more difficult. Parkinson's disease is both a chronic and progressive disease. Chronic means that it lasts for a long time. Progressive means the symptoms get worse over time. The symptoms of Parkinson's disease and the speed at which the disease progresses differ for each person.

Parkinson's disease occurs when brain cells containing dopamine in a specific part of the brain die or are damaged. Experts do not know for sure what causes the damage in these brain cells. They believe that Parkinson's disease may be related to one or more of the following:

	Chemicals called free radicals that build up in the brain and damage the cells that make dopamine
	Toxins (poisons) in the environment, such as pesticides
	Genetic factors — 15% to 20% of people with Parkinson's disease have a close relative with similar symptoms, such as shaking, slowness, and stiffness
	Faster-than-usual loss of the brain cells that make dopamine

Some experts believe that future studies will show that a combination of these factors may be the cause of Parkinson's disease. Others believe there are still unknown factors that may be important.

Each year in the United States, about 50,000 people are diagnosed with Parkinson's disease. A million or more Americans may have this disease. Parkinson's disease affects both men and women almost equally. People of every race, economic class, and ethnicity can get Parkinson's disease.

However, age is a clear risk factor. Most people who get Parkinson's disease are over the age of 50. But Parkinson's disease can strike at any age. The average start of the disease is age 60; however, doctors are now finding Parkinson's disease in a growing number of people under the age of 40. This is called early onset Parkinson's disease.