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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Sarah Long.

VOICE TWO:

And I'm Bob Doughty. On our program this week, we tell about Parkinson's disease, a disorder of the central nervous system.

VOICE ONE:

Many people around the world live with Parkinson's disease. In the United States, Parkinson's affects about five hundred thousand people. There has been recent interest in the disease because of some of those affected are very well known.

When Karol Wojtyla was elected pope in nineteen seventy-eight, he changed the image of the leader of the Roman Catholic Church. The new pope, John Paul the second, was known as a man who liked physical exercise. He swam and walked great distances.

Muhammed Ali also showed great energy and power as he became the boxing champion of the world. He was probably one of the sport's greatest competitors of the twentieth century.

However, as both men grew older, they began to change. Their energy began to disappear. Their movements became slower. Their faces seemed to be made of stone. Age makes all people lose the energy they had when they were younger. However, it was not age that changed these men so much. Their physical changes were caused by a sickness known as Parkinson's disease.

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Parkinson's disease is a disorder of the central nervous system. It is a disease that makes its victims increasingly unable to move. It affects a small area of cells in the middle of the brain called the substantia nigra. The cells slowly lose their ability to produce a chemical called dopamine. The reduced levels of dopamine can result in one or more of the general signs or symptoms of Parkinson's disease.

These symptoms include shaking of the arm or leg on one side of the body. Other symptoms are a general slowness of movement, or severe difficulty in moving the arms and legs. Another is difficulty walking and keeping balanced while standing or walking.

Other signs observed in some people include restricted or decreased movement of the face. Also, victims of Parkinson's disease can feel sad or worried. Victims may swallow less often than normal. And, they may have difficulty forming words while talking.

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Parkinson's disease is named after James Parkinson. He was a British doctor who first described the disease in Eighteen-Seventeen. But Doctor Parkinson did not know what caused it.

During the nineteen sixties, research scientists discovered chemical and other changes in the brains of people suffering from the disease. These discoveries led to medicines to treat Parkinson's disease. However, the cause of the disease is still a mystery.

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Most people have what is called idiopathic Parkinson's disease. Idiopathic means that the cause is unknown. Patients who develop the disease attempt to link it to some cause they can identify. These can include an accident, a medical operation, or emotional problems.

Most doctors, however, reject the idea of any direct link between these events or problems and Parkinson's disease. The doctors note that other people with similar problems do not develop a movement disorder such as Parkinson's disease. However, doctors say such events or problems may cause signs of the disease to be seen earlier than normal.

VOICE ONE:

There are other forms of Parkinson's disease. Some medicines for other problems can cause disorders similar to Parkinson's disease. These include medicines used to treat older people who see things that do not exist. And they include drugs used to treat people suffering from extreme tension or stomach problems.

The disease encephalitis also can cause movement problems and other disorders like those of Parkinson's disease. In the early twentieth century, encephalitis spread to many parts of the world. Many victims of the disease had symptoms similar to Parkinson's disease. This led to scientific investigations into the possibility that a virus caused Parkinson's disease.

However, no evidence was found to support this theory. One reason for rejecting the theory is that Parkinson's disease cannot be passed from one person to another the way other viral diseases can.

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Another common theory is that people with Parkinson's disease could pass it to their children. There are examples of many members of families having the disease.

Last month, the publication Lancet reported additional genetic evidence. It said a change in just one gene may affect the risk of Parkinson's disease. Researchers found that one in every sixty people with Parkinson's have changes in the gene called L-R-R-K-two. The researchers said the genetic changes could be responsible for five percent of all cases in people with a family history of the disorder. They said it also could cause up to two percent of idiopathic Parkinson's.

VOICE ONE:

Also, a small study suggested that chemical products used to kill insects could increase the risk of the disease. American researchers found that people who sprayed such products had two times the risk of developing Parkinson's than other people. They found farmers also had an increased risk, although much smaller.

Most of those suffering from the disease are older people. It reportedly affects one of every one-hundred people over sixty years old. However, fifteen percent of patients develop the disease before they are fifty years old. Also, it affects men a little more often than it affects women. And Parkinson's disease can be found among people in all parts of the world.

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Parkinson's disease does not cause death for those suffering from the condition. New treatments to ease symptoms of the disease make it possible for many patients to continue to live almost normally. Patients who have lost their ability to do many things may be able to regain some of their old abilities with treatment.

Perhaps the drug most commonly used to treat the disease is levodopa. When it reaches the brain, levodopa is changed to dopamine. It replaces the dopamine lacking in patients with Parkinson's disease.

Levodopa helps deal with the signs of the disease. It does not, however, prevent more changes in the brain caused by the disease. Levodopa can produce bad effects in some people. These side effects include feeling extremely sick to the stomach. To prevent this from happening, other substances can be combined with levodopa.

Most other drugs used to treat Parkinson's disease are designed to increase the amount of dopamine in the brain.

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Another way of treating Parkinson's disease is a medical operation. One such operation is called a pallidotomy. It was used often in the past to treat the disease. However, it was used less often after the discovery of levodopa.

More recently, improved technology has increased the chances of successful pallidotomies. The operation involves placing electrical devices directly on the brain. These devices target cells in the area that cause unwanted movements of the body. The most serious risk from this treatment is the possibility of the patient suffering a stroke.

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The most recent development in treatment of Parkinson's disease is brain tissue transplants. This involves replacing tissue in areas of the brain that cause symptoms of the disease. Early experiments involved brain tissue from unborn babies. Doctors said the method appeared to have successful results.

However, the experiments became a subject of moral debates among persons opposed to the ending of unwanted pregnancies.

Researchers have begun working with genetically changed cells and different animal cells that can be made to produce dopamine. Still, most doctors agree that such operations should be considered only after it is clear that drugs are not effective in dealing with the signs of Parkinson's disease.

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There is no way to prevent or cure Parkinson's disease. So, the victims of the disease need help in many ways. Throughout the world, there are groups that provide education and support services for patients and their families learning to live with the disease.

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This SCIENCE IN THE NEWS program was written by Oliver Chanler and Caty Weaver. This is Bob Doughty.

VOICE ONE:

And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.