Parkinson

’s Disease Essay, Research Paper

Introduction

Parkinson’s disease is a progressive disorder of the central nervous system affecting over 1 million people in the United States. Clinically, the disease is characterized by a decrease in spontaneous movements, gait difficulty, postural instability, rigidity and tremor. Parkinson’s disease is caused by the degeneration of the pigmented neurons in the Substantia Nigra of the brain, resulting in decreased dopamine availability. The Substantia Nigra is made up of cells called neurons or nerve cells which perform the work of the brain (Levin, 6). The major symptoms of the disease were originally described in 1817 by an English physician, Dr. James Parkinson, who called it “Shaking Palsy”. Only in the 1960’s, however, pathological and biochemical changes in the brain of patients were identified, opening the way to the first effective medication for the disease. (”Basic Information About Parkinson’s Disease”)

Both men and women are affected. The frequency of the disease is considerably higher in the over 50 age group, even though there is an alarming increase of patients of younger age. In consideration of the increased life expectancy in this country and worldwide, an increasing number of people will be victims of Parkinson’s disease. (”Basic Information About Parkinson’s disease”)

Body

No cure exists for Parkinson’s disease. Treatment usually centers on medications that provide relief from its symptoms. (”Treatment of Parkinson’s Disease”)

In prescribing treatment, physicians must assess the severity of the patient’s symptoms and match them to an appropriate form of therapy or medication. No two persons respond identically to a particular drug or dosage level, so this process involves a certain amount of experimentation, persistence, and patience. Results may be only partially successful, and even these may demand adjustment as the disease progresses. Physicians often begin by prescribing less powerful drugs, the anticholinergics or amantadine for example, reserving stronger medications like levodopa for later, when the disease’s progression necessitates more aggressive treatment. (”Treatment of Parkinson’s Disease”)

Levodopa (also called L-dopa), the active anti-Parkinson drug in Sinemet and its generic brands, is the single most beneficial drug to relieve symptoms of Parkinson’s disease. Levodopa is a short-acting drug that enters the brain and is converted into dopamine, the neurotransmitter that is low in Parkinson’s disease. Levodopa is combined with another drug called “carbidopa”, which enhances L-dopa’s action in the brain and minimizes side effects such as nausea. (”Treatment Methods”)

Dr. Jayashree Rao, of Tulane University, said, “Levodopa is the most popular drug treatment for Parkinson’s disease we have today. Although there, of course, are side effects, the results seem to be positive so far.”

Other medications are also used to treat Parkinson’s disease, as solo agents or in combination with Sinemet. Selegiline, marketed as Eldepryl in the U.S., may offer some relief from early Parkinson symptoms, and research is still ongoing to determine if it might also have some neuro-protective benefit. (”Treatment Methods”)

Amantadine (Symmetrel) is an anti-viral drug that also provides an anti-Parkinson effect; it is most frequently used to widen the “therapeutic window” for Levodopa when used in combination with Sinemet. (”Treatment Method”)

Benadryl, Artane, and Cogentine are brand names for anti-cholinergic agents that may be prescribed to treat tremors. While effective, these drugs can have side effects such as dry mouth, blurred vision, urinary retention and constipation, which limit their use in older adults. Bromocriptine (Parlodel) and Pergolide (Permax) are dopamine agonists. These drugs enter the brain directly at the dopamine receptor sites, and are often prescribed in conjunction with Sinemet to prolong the duration of action of each dose of levodopa. They may also reduce levodopa-induced involuntary movements called “dyskinesias”. The physician slowly titrates a dopamine agonist to a theraputic level, then gradually decreases the levodopa dose to minimize dyskinesias. (”Treatment Methods”)

Two new dopamine agonists, Ropinirole (Requip) and Pramipexole (Mirapex), have shown great promise in extensive clinical trails. Both have lower side-effect profiles than others available in the U.S. (”Treatment Methods”)

Tolcaponc (Tasmar) and Entacapone, drugs classified as COMT (catechol-0-methyl-transterase) inhibitors are near the end of clinical trials. Their mechanism of action is totally different than that of dopamine agonists. When COMT activity is blocked, dopamine remains in the brain for a longer period of time. These two medications offer new options to treat Parkinson’s disease. (”Treatment Methods”)

Research funded by agencies such as the NPF and major pharmaceutical firms has been very successful over the past decade in providing more and better medications to improve the quality of life for Parkinson patients. There is realistic hope for a cure in the foreseeable future from medication advances or surgical innovations. (”Treatment Methods”)

Early efforts with adrenal medulla transplants and fetal tissue implantation, led to more sophisticated procedures such as thalamotomy for tremor, and pallidotomy to reduce overall Parkinson disability. One of the latest advances in neurosurgery is controlled trials with deep brain stimulation, wherein an electrode is planted deep within the brain and controlled by the patient with an on/off magnetic device. (”Treatment Methods”)

Most physicians agree that brain surgery is a reasonable option only for patients who are no longer responsive to optional medication management. (”Treatment Method”)

Conclusion

The cause of Parkinson’s disease is unknown. At this time there is no cure; however, there are many medicines available to help alleviate the symptoms. It is important to be treated by a neurologist. (Levin, 6)

Many patients are only mildly affected and need no treatment for several years after the initial diagnosis. When symptoms grow severe, doctors usually prescribe levodopa (L-dopa), which helps replace the brain’s dopamine. Sometimes doctors prescribe other drugs that affect dopamine levels in the brain. In patients who are very severely affected, various kinds of brain surgery have reportedly been effective in reducing symptoms. These surgical approaches include pallidotomy and implantation of an electrical stimulator to counteract the effect of the loss of dopamine-producing cells in the substantia nigra. Another kind of brain surgery, in which healthy dopamine-producing tissue is transplanted into the brain, is also being tested. Finally, researchers are trying to discover substances that will prevent dopamine-producing brain cells from dying. Now that it is possible to identify individuals in some families genetically prone to developing Parkinson’s disease, scientists plan to test methods of halting or at least delaying the disease’s progression. (”What treatments are available?”)

Book:

Levin, Susan B. Coping With Parkinson’s Disease. Staten Island, New York. American

Parkinson’s Disease Association. 1986.

Internet:

“Basic Information About Parkinson’s Disease”. June 22, 2000. American Parkinson’s

Disease Association. Online. America Online. 5 July 2000.

“Treatment Methods”. 1996-2000 The National Parkinson Foundation, Inc. Online.

America Online. 3 July 2000.

“Treatment of Parkinson’s Disease”. June 22, 2000. Neurology Channel. Online. America Online. 28 June 2000.

“What Treatments are Available”. American Parkinson’s Disease Association. Online.

America Online. 22 July 2000.

Personal Interview:

Rao, Jayashree MD, Tulane University. Personal Interview. June 30, 2000.