What is Parkinson's disease?

Parkinson's disease (PD) is a chronic (persistent, or long-term) disorder of part of the brain. It is named after the doctor who first described it. It mainly affects the way the brain co-ordinates the movements of the muscles in various parts of the body.

PD mainly develops in people over the age of 50. It becomes more common with increasing age. About 5 in 1,000 people in their 60s, and about 40 in 1,000 people in their 80s have PD. It affects both men and women but is a little more common in men. Rarely, it develops in people under the age of 50.

PD is not usually inherited, and it can affect anyone. However, genetic (hereditary) factors may be important in the small number of people who develop PD before the age of 50.

A small part of the brain called the substantia nigra is mainly affected. This area of the brain sends messages down nerves in the spinal cord to help control the muscles of the body. Messages are passed between brain cells, nerves and muscles by chemicals called neurotransmitters. Dopamine is the main neurotransmitter that is made by the brain cells in the substantia nigra.

If you have PD, a number of cells in the substantia nigra become damaged and die. The exact cause of this is not known. Over time, more and more cells become damaged and die. As cells are damaged, the amount of dopamine that is produced is reduced. A combination of the reduction of cells and a low level of dopamine in the cells in this part of the brain causes nerve messages to the muscles to become slowed and abnormal.

The brain cells and nerves affected in PD normally help to produce smooth, co-ordinated movements of muscles. Therefore, three common Parkinson's symptoms that gradually develop are:

The symptoms tend slowly to become worse. However, the speed in which symptoms become worse varies from person to person. It may take several years before they become bad enough to have much effect on your life. At first, one side of your body may be more affected than the other.

Some other symptoms may develop due to problems with the way affected brain cells and nerves control the muscles. These include:

Various other symptoms develop in some cases, mainly as the condition becomes worse. These include:

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Parkinson's Disease. Symptoms of parkinson's disease | Patient