Research Paper over Lung Disease

Parkinson’s Disease

HPRS 2301.271

Jane Doe

July 15, 2009

Parkinson’s disease is a progressive, disabling brain disorder. It occurs when brain cells, or neurons, decline and cause a deficiency in the chemical brain messenger, dopamine. Dopamine helps the nervous system control muscle activity. The low supply of dopamine causes the major symptoms of this disease.

Signs & Symptoms

The symptoms of Parkinson’s disease vary from person to person. However, there are four main motor features that characterize the disease: tremors, bradykinesia (slowness of movement), rigidity (stiffness), and postural instability (poor balance). The classic Parkinson’s disease tremor is a rhythmic back-and-forth movement of the thumb and forefinger, sometimes described as “pill rolling”. Other common signs include: shuffling gait, stooped posture, problems with fine motor coordination, and small handwriting. Non-motor symptoms of the disease include sleep disorders, a decrease in cognitive abilities, and mood disorders such as depression. Some may notice that the face takes on a mask-like appearance, which is due to the loss of automatic muscle movements.

Parkinson’s disease can be divided into five stages. In stage one of the disease, the signs and symptoms appear only on one side of the body. The symptoms are mild and may be inconvenient, but they are not disabling. Stage two is characterized by the symptoms appearing on both sides of the body. The symptoms cause minimal disability, and the posture and gait are affected. By stage three, body movements are slowed significantly. The symptoms cause moderately severe problems with normal functioning. The fourth stage produces symptoms that are severe. The individual can still walk, but only to a limited extent. As a result of the individual’s rigidity and slowness of movement, they have a tendency to fall. Therefore, the person should no longer live alone. The fifth stage results in the complete debilitation of the patient. However, early self-help and drug therapy may delay or even prevent this stage. (Cram, 1999)

Parkinson’s disease commonly occurs in older individuals, with the mean age of onset being approximately 60 years old. Men have more of a tendency to develop Parkinson’s disease than women, and the normal life span expectancy after diagnosis is around 10 years.

Etiology

“Many symptoms of Parkinson’s disease result from the lack of a chemical messenger, called dopamine, in the brain. The lack of dopamine occurs when the specific brain cells that produce dopamine die or become impaired” (Mayo Clinic staff, 2009). Unfortunately, doctors are not sure what causes the degeneration of the brain cells that produce dopamine. Thus, the specific cause of the disease is unknown. Although the specific cause of the disease is unknown, scientists have a few theories about certain factors that seem to have a higher incidence of occurrence in people that are diagnosed with Parkinson’s disease.

“There is some evidence that certain toxins in the environment may cause Parkinson’s disease. Scientists have suggested that external or internal toxins may selectively destroy the dopaminergic neurons, causing Parkinson’s disease. Toxins that may be linked to Parkinson’s include manganese, carbon monoxide, carbon disulfide and some other pesticides” (WebMD, 2005).

Another theory regarding the cause of Parkinson’s disease is oxidative stress.

Oxidation is a process in which free radicals (unstable molecules lacking one electron), in an attempt to replace the missing electron, react with other molecules (such as iron). Free radicals are normally formed in the brain and body, but usually the brain and body have mechanisms to get rid of free radicals. In people with Parkinson’s disease, the mechanisms that rid the brain and body of free radicals may not be effective or they may produce too many free radicals. It is also possible that environmental toxins may contribute to abnormal free radical formation and lead to Parkinson’s disease. Oxidation is thought to cause damage to tissues, including neurons. (WebMD, 2005)

Diagnosis

Parkinson’s disease may be difficult to diagnose as it may be confused with normal age-related changes. The diagnosis of Parkinson’s disease is made by evaluation of the patient’s history, neurologic examination, and the patient’s response to drug replacement therapy. “The best clinical predictors of a pathology diagnosis include asymmetry of the onset, presence of resting tremor, and a good response to dopamine replacement therapy. There are no blood tests that make the diagnosis and a CT and MRI of the brain are typically unrevealing” (Hauser, et al., 2006). These diagnostic imaging tests are typically used to rule out other diseases such as Wilson’s disease and Huntington’s disease, which may produce PD-like symptoms.

Treatment

To date, there is no known cure for Parkinson’s disease. Treatment is aimed at controlling the symptoms associated with the disease. The most common treatment options include drug therapy, physical therapy, and surgery. “The right drugs can often help recover many lost body functions, protect against further disability, and help those with Parkinson’s disease maintain independence for many years” (Cram, 1999).

Levodopa has been found to be the most effective drug to alleviate the symptoms associated with Parkinson’s disease.

Levodopa enters the brain and is converted to dopamine. Dopamine itself cannot be absorbed directly due to the fact that it alone cannot cross the blood-brain barrier; however, levodopa is able to and enzymes there convert it into dopamine. Levodopa is combined with a second drug, carbidopa, which inhibits certain enzymes that break down large amounts of levodopa from doing so before levodopa can reach the brain; therefore, more levodopa reaches the brain. Carbidopa also helps reduce the side effects such as nausea, vomiting, abdominal stress, and heart problems. (Cram, 1999)

Unfortunately, the effectiveness of levodopa has a tendency to decrease after long periods of time. The potential side effects of levodopa include: confusion, delusions and hallucinations, low blood pressure, heart arrhythmias, as well as involuntary movement called dyskinesia.

Dopamine agonists are another class of drugs that are used to treat Parkinson’s disease. By attaching themselves to dopamine receptor sites in the brain, these drugs cause neurons to react as though dopamine is present (Cram, 1999). As a result, the patient experiences relief of their symptoms.

Though these drugs may not be as effective as levodopa, they last longer, and are often used to smooth the sometimes off-and-on effect of levodopa. Commonly prescribed dopamine agonists include: bromocriptine (Parlodel), pramipexole (Mirapex), and ropinirole (Requip). The side effects of dopamine agonists include those of carbidopa-levodopa; although, they are less likely to cause involuntary movements. However, they are substantially more likely to cause hallucinations, sleepiness or swelling. These medications may also increase the risk of compulsive behaviors such as hypersexuality, compulsive gambling, and compulsive overeating. (Mayo Clinic staff, 2009)

Other forms of drug therapy include enzyme inhibitors such as MAO B inhibitors, COMT inhibitors, anticholinergics, and anti-viral medications.

Physical therapy is another form of treatment that may prove to be helpful in controlling patient’s symptoms. Physical therapy can help improve mobility, range of motion, and muscle tone. A physical therapist can also work with patients to improve their gait and balance. A speech therapist can improve problems that occur with speaking and swallowing and an occupational therapist can help with therapies that may maintain or improve muscle coordination and dexterity.

“Neurosurgery to treat Parkinson’s disease symptoms was first performed in the 1930’s. Surgery usually involves damaging specific areas of the brain involved in motor function in an attempt to reduce severe symptoms such as an uncontrollable tremor” (Cram, 1999). The four most common types of surgical procedures for Parkinson’s disease are: pallidotomy, thalamotomy, deep brain stimulation surgery, and neural implant surgery. The most common of these four is the deep brain stimulation surgery.

“Parkinson’s disease is one of the few neurodegenerative diseases whose symptoms can be improved with medication therapy” (Hauser, et al., 2006). Though there is no cure for Parkinson’s disease, the many available therapies can help the patient control and maintain the symptoms associated with the disease and allow them to continue on with day to day life.

Bibliography

Cram, M. D. (1999). Understanding Parkinson's Disease A Self-Help Guide. Omaha, Nebraska:

Addicus Books, Inc.

Hauser, M. R., Zesiewicz, M. T., Lyons, P. K., Pahwa, M. R., Golbe, M. L., Stacy, M. M., et al.

(2006). Parkinson's Disease Questions and Answers (Fifth ed.). (M. Robert A. Hauser,

Ed.) West Palm Beach, FL: Merit Publishing International.

Mayo Clinic staff. (2009, January 14). MayoClinic.com reprints. Retrieved July 14, 2009, from

MayoClinic: http://www.mayoclinic.com/health/parkinsons-

disease/DS00295/DSECTION

WebMD. (2005, June 1). Parkinson's Disease: What Causes it? (M. Cynthia Dennison Haines,

Editor) Retrieved July 14, 2009, from WebMD: http://www.webmd.com/parkinsons-

disease/parkinsons-causes