PARKINSON'S DISEASE

Biology 103
Web Reports 1997
From Serendip

Alicia Ebbitt

I chose Parkinson's Disease to study for my WWW project because my Grandfather has Parkinson's and I wanted to learn more about it. The progression of this disease in my grandfather is extremely sad, and I was interested in learning exactly what is going on in his brain. I am also extremely curious about the most research on the disease, what is being done to find a cure, and whether or not it is a hereditary disease. Parkinson's Disease is a chronic neurological disorder that deteriorates the Basal Ganglia section of the brain. This results in the destoration of nerve cells in the brain that produce dopamine. As a result, a person with Parkinson's suffers from a severe dopamine deficiency. Dopamine is a neurotransmitter in the brain that helps the nervous system control movement. The symptoms of Parkinson's are a direct result of dopamine depletion.

There are over a million victims of Parkinson's in the United States alone. There are 20 new cases of Parkinson's Disease per 100,000 people per year (11). Parkinson's usually affects people over the age of 50. Parkinson's is slightly more common in men than in women. Though Parkinson's affects people all over the world is slightly more common in whites than in African Americans and Asians (5). Though the cause of Parkinson's is currently unknown, there are many theories on its etiology.

There are currently four theories on the cause of Parkinson's Disease and many scientists believe that it is probably a combination of 1 or more of the following factors. Parkinson's may be the result of environmental factors such as drinking well water, living in the rural communities, and exposure to heavy metals. Carbon monoxide poisoning, carbon disulphide, potassium cyanide, and methyl alcohol may also contribute to an environmental cause of Parkinson's. Some scientists have implicated manganese ore dust as a possible cause as well. Through recent research, and testing it has been determined that no one environmental agent could be the only cause of Parkinson's Disease (8).

The narcotic drug, MPTP has been known to destroy parts of the brain. This has often resulted in many of the symptoms of Parkinson's Disease (8). Infectious disease has been suggested as a possible cause of Parkinson's as well. In the early 1900's, there was an epidemic of an illness that caused people to fall into a stupor or suffer severe insomnia. This disease was called sleeping sickness or encephalitis lethargic. Many of the victims of this disease developed a certain form of Parkinson's Disease (8). Still other scientists believe that Parkinson's Disease may be a direct result of the process of accelerated aging. This process occurs for currently unknown reasons. Through this aging, some of the brain's ability to produce dopamine decreases. This results in many of the symptoms of Parkinson's Disease (8).

Some genetic researchers believe that Parkinson's Disease has a genetic cause and is therefor hereditary. In many families, Parkinson's has occurred in many generations. This group of victims tends to follow one side, either the mother or the father. Studies show that first-degree relatives of Parkinson's victims are two times more likely to develop the disease than relatives in families in which there is no history of Parkinson's. By studying families in which Parkinson's has passed of through generations, researchers have identified an abnormal gene that has been the cause of some cases of Parkinson's Disease. This gene is located on chromosome 4. However, in some Parkinson's patients there is no genetic link and it does not run in the family. For this reason, genetic studies on Parkinson's remain controversial. Most scientists believe Parkinson's is caused by a combination of environmental and genetic influences. ((5), (6), and (12)).

The initial symptoms of Parkinson's are often subtle and may be nonspecific. For this reason, Parkinson's may unfortunately go undetected for a long time.

The primary symptoms of Parkinson's include, rigidity, tremors, bradykinesia, difficulty with balance, and difficulty with walking. Many patients also suffer from secondary symptoms as well. These include, depression, sleep disturbances, dementia, forced eyelid closure, speech problems, drooling, difficulty in swallowing, weight loss, constipation, breathing problems, difficulty in voiding, dizziness stooped posture, swelling of the feet, and sexual problems (11). Rigidity is increased tone in muscles. Rigidity is present when limbs are still, but increases as they move. It is related to over elasticity of specific nerve cells in the spinal cord that control muscle tone. Tremors appear in the hands and often in the feet, head neck, face, and jaw. Tremors are often worse on one side of the body than on the other.

Bradykinesia is an extremely disabling symptom of Parkinson's in which the victim is delayed in their movements. In many Parkinson's patients this results in the slowness of all movements, and the arrest of many ongoing movements. Parkinson's patients often have an inability to maintain equilibrium or react to abrupt changes in positions and often suffer falls. Some Parkinson's victims also have difficulty in walking, initiating walking, and difficulty in turning. This may be further affected by bradykinesia and difficulty with balance. These primary symptoms are a direct result of the dopamine deficiency in the brain. Most secondary symptoms are the result of this deficiency as well.

Depression, sleep disturbances, dementia(including paranoia, confusion, and hallucinations), as well as difficulty with voiding, and dizziness may be direct side effects of anti-Parkinsonian drugs.((11) and (3)). Though no cure has currently been found for Parkinson's Disease, most patients can be administered drugs that either are converted to dopamine in the brain, bind to the dopamine receptors in the brain, block the breakdown in the brain, or simply help to reduce Parkinson's symptoms. In some special cases, surgical treatment may be used on Parkinson's patients as well (13).

Sinemet is the most common medication for treating Parkinson's victims. It is the combination of levodopa and carbidopa. Levodopa is converted into dopamine in the brain and replenishes dopamine levels. This helps to relieve Parkinson's symptoms. Carbidopa helps to make the medication more effective. The most common side effects of Sinemet are nausea, anorexia, dizziness, bradykinesia episodes, hallucinations, and restlessness. A few less common side effects of the medication are hypertension, phlebitis, anemia, involuntary movements, and duodenal ulcer. A few risks that accompany any this medication are depression, confusion, delusions, and paranoid ideation (14).

Bromocriptine and pergolide copy the role of dopamine in the brain. They cause nerve cells to react as they would to dopamine. They are usually less effective than levodopa in controlling rigidity, and bradykinesia. Some of the side effects of these drugs may include, paranoia, hallucinations, confusion, dyskinesias, nightmares, nausea, and vomiting (4).

Selegine, otherwise known as eldepryl or deprenyl has inhibiting effects on the enzyme Monoamine Oxidase Type B. This enzyme inactivates dopamine in the brain. When this enzyme is stopped, dopamine levels increase. The most common side effects of Selegine are nausea, dizziness, insomnia, agitation, hallucinations, and confusion. Some less common side effects are depression, involuntary movements, and headaches. One of the risks involved in taking this drug is drug interactions (9).

Anticholinergics are drugs that have limited effects but may help control tremor and rigidity. Anticholinergics can help reduce drug-induced Parkinsonism. These drugs block the action of acetylcholine, a brain chemical that is more harmful when dopamine levels drop. The common side effects of these drugs are dry mouth, constipation, urinary retention, hallucinations, memory loss, blurred vision, changes in mental activity and confusion (4).

Amantadine is an antiviral drug that helps reduce symptoms of Parkinson's Disease. Its effectiveness often wears off in many patients. Several of Amantadine's side effects include, mottled skin, edema, confusion, blurred vision, and depression (13).

In some special cases, surgery can be used as a form of treatment for Parkinson's. the use of surgery is however quite restricted since the introduction of drugs like levodopa. One procedure used is cryothalamotomy. This involves the surgical insertion of a supercooled metal tip of a probe into the thalamus. This process destroys the brain area that produces tremors. In pallidotomy, another surgical procedure, a portion of the brain called the globus pallidus is lesioned. This may help improve symptoms of tremors, rigidity, and bradykinesia 4).

Though Parkinson's Disease is a chronic, deteriorative, progressive disease, much research is being done to find new ways to reduce its symptoms and increase dopamine in the brain. Everyday, new discoveries are made that bring us closer to finding a cure or making it easier for Parkinson's patients to function in everyday situations.

Bibliography

1) Genetic Defect May point to Heredity as a Source of Parkinson's Disease, from Doctor's Guide to Medical and Other News

2) Parkinson's Disease, from Healthguide OnLine!

3) Symptoms, Diagnosis, and Forms, from Healthtouch Online: Parkinson's Disease

4) Treatment, from Healthtouch Online: Parkinson's Disease

5) General Information, from Healthtouch Online: Parkinson's Disease

6) Is There a Connection Between Parkinson's Disease and Genetics?, from OnHealth

7) The National Parkinson's Foundation, Inc.

8) Parkinson's Disease: Etiology and Genetics, from HealthGuide Online!

9) Parkinson's Disease Medications: Selegine, Eldepryl, and Deprenyl, from HealthGuide Online!

10) Parkinson's Disease: What is Parkinson's Disease?, from the Parkinson's Institute

11) The Parkinson's Web, from Massachusetts General Hospital.

12) Scientists Close in on a Parkinson's Gene, from the Parkinson's Disease Foundation

13) Parkinson's Disease Medications, from HealthGuide Online!

14) Parkinson's Disease Medications: Sinemet, from HealthGuide Online!

 

 

Continuing conversation (to contribute your own observations/thoughts, post a comment below) 12/23/2005, from a Reader on the Web I am interested in finding out more about the possible hereditary nature of parkinson's - my husband's father had a slow developing one - he died quite late at 82. He had various symptoms quite early one - around 60 - that forced a number of life changes. Primary amongst these was an inability to make decisions and a worry about everything - forcing sale of house etc because he felt unable to deal with these sort of things. Am interested in finding out about early signs of these things - which may just be put down to some sort of depression. Thank you.