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We all lose brain cells as we age -- and most of them aren't really missed. But when the wrong cells stop doing their job, a person can become seriously ill.

Certain nerve cells, for example, have the vital job of producing dopamine, a compound that relays messages between parts of the brain that tells muscles how to move smoothly. People develop Parkinson's disease when these cells -- which help control muscle movements -- stop working.

One theory is that genes are to blame; another is that nerve cells are harmed by chemicals in the environment, and gradually stop sending messages to each other. When the supply of dopamine dwindles, the messages to the muscles get garbled. As the communication breakdown continues, you slowly lose control over your body, particularly over the muscles that control walking and balance.

Some viruses, such as a certain strain of influenza A, may also be responsible for bringing on Parkinson's. An unusual number of people born in the early part of the century, particularly after the 1918 influenza epidemic in the United States, developed Parkinson's later in life, pointing to a possible link between viral infections and nerve damage.

Many patients eventually have trouble walking, driving, and performing simple daily tasks. Parkinson's disease is a chronic, progressive condition, and, if left untreated, the symptoms will grow steadily worse.

But if you have Parkinson's, don't give up hope: Researchers are making progress in developing new treatments. Treatment for the disease has improved dramatically in recent years, and many patients continue to lead rewarding lives. With the right medications and a healthy lifestyle, you may well be productive and active.

In the earliest stages, the signs of Parkinson's disease are subtle and easy to overlook. You may feel unusually tired, anxious, irritable, and depressed, and you may have trouble sleeping. Your fingers may shake a bit when at rest, or you may drag a foot when walking. You may have trouble doing things with your hands, such as buttoning your shirt and holding forks or spoons. Some people freeze, unable to move, slur their words and have trouble swallowing. Friends and family may notice less expression in your face, and you may seem a bit stiff or slow.

As months and years go by -- and as more brain cells are damaged or die -- the symptoms will grow worse. Most patients develop uncontrollable shaking, or tremors, in their hands. Often, the tremors make it impossible to hold a book or a cup of coffee. Tremors may also affect your jaws, face, arms, and legs. You may find that your trunk and limbs are stiff, and that your movements are slowing down. You may also have problems with balance and be unsteady on your feet. Some people also have trouble with memory or speech, while others may suffer from cognitive impairment or dementia.

No laboratory test can detect Parkinson's disease, and many other conditions can cause similar symptoms. For this reason, your doctor will have to observe you carefully before diagnosing you with Parkinson's disease.

If you do have a tremor, don't leap to the conclusion that you have Parkinson's disease. There are a number of common conditions that could also make your hand tremble. Check with a doctor before assuming your shaking is a sign of other serious Parkinson's symptoms to come.

There's no doubt that damaged or dying nerve cells in a part of the brain known as the substantia nigra cause Parkinson's disease, but nobody knows why this occurs. Certain genes seem to make these cells easier to harm, but what actually pulls the trigger? Some experts blame pesticides and other poisons, some point to viruses or oxidation damage in the brain, and some speculate that in some people the brain simply ages faster than usual. Many researchers believe that it takes a combination of these factors -- plus genetics -- to actually cause the disease, according to the National Institutes of Health.

Parkinson's disease seems to pick its victims almost at random. It's slightly more common in people with a family history of the disease, and it strikes a few more men than women. But patients don't fit a single profile. They come in all races, lifestyles, and body types. And even though the disease usually happens to people over age 50, people in their 40s, 30s, or even 20s aren't immune. As many as 15 percent of all patients -- including actor Michael J. Fox -- contract the disease under age 50. Most Parkinson's patients, however, are older, including Attorney General Janet Reno, evangelist Billy Graham, and boxer Muhammad Ali.

According to the Parkinson's Disease Foundation, about 1 million Americans suffer from the condition, and another 40,000 are diagnosed every year. The disease isn't contagious and isn't passed directly from one family member or generation to the next.

There is no cure for Parkinson's, but your doctor can prescribe drugs to drastically reduce your symptoms. In the earliest stages of the disease, you may not need medications at all. As symptoms get a bit worse, your doctor may suggest amantadine, an antiviral drug that can buy you at least several months of relief. But eventually, all patients will need more serious medication to help them carry on their lives.

At some point, almost everyone with Parkinson's will take levodopa (also known as L-dopa) -- a drug seemingly capable of miracles. The brain converts levodopa into dopamine, thus replenishing the supply of this crucial compound as well as restoring, at least temporarily, long-lost physical abilities. You may remember levodopa from the movie "Awakenings," which was based on a true story. With one shot of the drug, the character played by Robert DeNiro awoke from a long coma brought on by a Parkinson's-like disease.

For Parkinson's patients, the response to levodopa can be almost as dramatic. In some cases, the disease seems to disappear, at least temporarily. The drug can give a patient years of normal, productive living when they would have otherwise been disabled. Levodopa is especially useful for relieving slowness and stiffness, but it has a limited effect on tremors.

The NIH calls levodopa a "triumph of modern medicine," but the drug has drawbacks. For one thing, it only helps about 75 percent of all patients. (Some of these patients may be misdiagnosed.) It can also cause nausea, vomiting, low blood pressure, involuntary movements, and restlessness. Patients who take the drug for several years can begin to suffer serious symptoms whenever the effects of the medicine begin to wear off.

More importantly, levodopa can't revive dead brain cells or slow the progression of the disease. As the disease grows worse, a patient needs ever-increasing doses to keep symptoms in check. Eventually, a person may need to take the drug every 90 minutes.

Doctors can reduce this problem somewhat by combining the drug with carbidopa, a compound that prevents levodopa from being converted into dopamine in the bloodstream, allowing more of it to get to the brain. According to the Parkinson's Disease Foundation, levodopa combined with carbidopa represents a significant improvement in treatment. The addition of carbidopa allows for a lower dose of levodopa to be used and therefore reduces some of its negative side effects.

Recognizing that levodopa has drawbacks, researchers have continued to develop new drugs for treating Parkinson's. One effective medication, selegiline, protects brain cells from damage. If used in the early stages of the disease, selegiline can delay the need for levodopa. And when prescribed in combination with levodopa, selegiline may slow the onset of disability.

More than a dozen drugs have been approved by the Food and Drug Administration to treat Parkinson's. Some have side affects such as constipation and increased blood pressure, so see your doctor if you experience any unusual symptoms.

Many patients find that regular exercise or physical therapy helps them move freely and keep their balance. Ask your doctor about exercise programs, or find some time to walk around the neighborhood or work in the garden.

Just like everybody else, people with Parkinson's disease should try to eat a healthy, well-balanced diet with plenty of fruits and vegetables. However, there are no special foods or supplements that seem to prevent Parkinson's or ease the symptoms. (Doctors once suspected that tocopherol, a form of vitamin E could delay the disease, but careful studies showed little reason for optimism.) If you're taking levodopa, keep in mind that a high-protein diet could interfere with the drug's power.

When medications stop working, some patients seek relief from tremors and rigidity through surgery. One procedure involves destroying the overactive nerve cells by burning a small spot of the brain that causes shaking. Another procedure involves implanting a wire in the brain that delivers a mild electrical signal, which blocks the brain signals that cause tremors. These surgeries do involve some risk, but some patients have reported a significant drop in shaking that lasts several years.

As you continue your fight against Parkinson's, you'll feel much better if you reach out for support. Call the American Parkinson's Disease Association at 1-800-223-2732 for a support group near you.

-- Chris Woolston, M.S., is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was the staff writer at Hippocrates, a magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, and the Chronicle of Higher Education. His reporting on occupational health earned him an award from the northern California Society of Professional Journalists.

Further Resources

American Parkinson Disease Association Inc.

135 Parkinson Ave.

Staten Island, NY 10305

718/981-8001 or 800/223-2732

http://www.apdaparkinson.org

Parkinson's Disease Foundation, Inc.

1359 Broadway, Suite 1509

New York, NY 10018

212/923-4700 or 800/457-6676

http://www.pdf.org

References

Last updated July 30, 2008
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