Parkinson's Disease
From Psy3242
Contents |
Overview
Parkinson's disease, otherwise known as PD, is the second most common neurodegenerative disease. The disease was named after its discoverer, James Parkinson in 1817. Parkinson's disease begins to show side effects when about 80% of the nerve cells in the substantia nigra, part of the basal ganglia, die and become impaired. These cells are responsible for the production of dopamine, a neurotransmitter that regulates our motor coordination and functioning. The substantia nigra is incharge of dopamine production that is carried through two different pathways "direct" and "indirect". The direct pathway facilitates movement. In PD, this area usually becomes less active, whereas, the indirect pathway becomes more active, in charge of inhibiting unwanted movements. The disease can be considered "idiopathic", meaning that it has no known cause, or "secondary", meaning it results from genetics, the post encephalitic epidemic, head trauma, MPTP, or Lewy bodies in the brain. Patients with PD are described as, "intellectually alert humans, in a disobedient body". Parkinson's is a terminal illness, but is a very slow process, so it is often that people die of unrelated illnesses before PD takes their lives.
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Symptoms
- Tremors
- Dystonias, or persistent muscle spasms, are common during resting states and usually not present in deliberate movements. These tremors cause frequent trembling of the limbs.
- Slowness of Movement
- Bradykinesia, the slowed ability to initiate and maintain movements, is a common side-effect in PD patients. Repetitive movements such as tapping and clapping are frequent in their behavior. Once movement is initiated, most of the time patients are able to continue the movement fluidly, until they become distracted or interrupted. This slowness also is exhibited in their coordination, they are unable to move their limbs quickly, or carry out planned motor tasks. Patients try to find "tricks" to help them initiate movements, external cuing. For example, a pattern on the floor or hearing music sometimes helps patients to start their motions. As PD progresses, it can eventually lead to Akinesia, or the inability to move spontaneously at all.
- Rigidity
- Muscular rigidity is a symptom common of PD. Cogwheel rigidity, a type of stiffness characterized by jerks associated with forcing a limb to move, is another common indicator of this disease. The muscles cycle through loose, then tense, then loose, then very tense phases, making the patient very tired. A "masked" appearance to the face makes the patient seem emotionless because of their inability to control their facial muscles. When muscles tense simultaneously, the sensation can be very painful.
- Difficulty with Balance
- Patients can experience trouble walking. An unbalanced gait can lead to a shuffling walk. This shuffle is typical of Parkinson's patients and some experience tripping and falling frequently because of it.
- Difficulty with Speech
- Some Parkinson's patients are atonal and hard to understand. Bradykinesia plays a role in language production, as well, making it difficult to speak. Patients sometimes have problems with excessive drooling and trouble swallowing.
- Sleep Complications
- PD patients have problems falling asleep, staying asleep, restless leg syndrome, and sometimes nightmares as a result of medications or the actual disease itself. Also, a possible reason for sleep complications could be because of a patients inability to toss and turn to make themselves comfortable.
- Depression
- Depression has been noted to be a symptom associated with PD for 25-40% of patients because of the damper the disease has put on their life and side-effects of the medications.
- Cognitive Executive Dysfunctions
- Because dopamine regulates the prefrontal cortex, problems associated with frontal lobe functioning can sometimes occur. Dementia is a symptom, but not as common as the others. Patients that experience these executive dysfunctions exhibit difficulties planning, organizing, carrying out cognitive and motor plans, trouble completing a Rey Complex Figure test, difficulties with the Wisconsin Card Sorting Task, problems with spontaneous recall of memory problems without external cues, and bradyphrenia. Bradyphrenia is a condition in which the patient has a slowed reaction time and slowed thinking, although this could be associated with their motor deficiencies.
- Skin Sensations
- From time to time, PD patients can experience a tingling feeling in their limbs.
How Parkinson's Disease is Assessed
Doctor's typically use the Unified Parkinson's Disease Rating Scale (1989)to assess patients. Unified Parkinson's Disease Rating Scale
Treatments Available
- Physical and Intellectual Exercise
Physical and intellectual exercises are strongly encouraged by specialists. Patients that participated in physical therapy and massages showed increased flexibility, range of motion, and balance. Patients that exercised their brain by doing intellectual tasks, showed slower rates of dementia.
- Medications
The medications given for PD are targeted to reduce the symptoms of the disease and increase dopaminergenic input into the two pathways of the basal ganglia motor loop, direct and indirect.
- Sinemet is a common medication used to treat the symptoms. It is a hybrid of carbl dopa, a medication allowing dopamine to pass through the blood brain barrier with reduced side-effects, and L-dopa the precursor of dopamine. The problem associated with this medication is that most patients develop intolerance to it 5 to 10 years after taking it. The medication only lasts for two hour periods and patients experience "on/ off" phases associated with it. Dyskinesias, or tics, are frequently associated with the "on" phase, while in "off" phases patients can exhibit akinesia.
- Amantadine is another medication sometimes used for PD patients. This is an antiviral medication used to potentiate the effects of dopamine in the brain.
- Catechol-o-methyltransferase, also known as COMT, is another drug used to treat PD. It is an monoamine oxidase inhibitor, meaning that is prevents the breakdown of dopamine in the brain.
- Surgery
When medications are no longer effective, surgery is an option for patients with Parkinson's Disease.
- Pallidotomy is a procedure used to treat PD. In this procedure, doctors laterally lesion the ventrointermediate nucleus located in the thalamus of the globus pallidus interna. This procedure can reduce symptoms of the disease and its effects last around 2 years.
- Another option is Deep Brain Stimulation. In this procedure, a pulse generator is planted in the skin of the chest and a corresponding multi-electrode is implanted into the ventrointermediate nucleus of the thalamus. Patients wave a magnet over the generator in their chest to turn the electrode on or off. When on, the patient receives electric stimulation to the thalamus, blocking tremors. The problem with this procedure is that the battery must be replaced every five years, meaning that the patient would need to undergo another expensive surgery. There are also various side-effects associated with this procedure as well; tingling in limbs, loss of balance, depression, slight paralysis, slurred speech, and loss of muscle tone.
Some Famous People with Parkinson's Disease
- Jack Buck
- Salvador Dali
- Mao Zedong
- Michael J. Fox
- In the 2006 senate election, Michael J. Fox appeared in a commercial endorsing Claire McCaskill, the democratic candidate, for her support of federal funding of stem cell research. A conservative radio talk show host bashed the commercial stating that Michael J. Fox was over exaggerating the symptoms of his disease because of his shaky appearance in the commercial. In actuality, it was not the symptoms of PD that was illuminated; it was the effects of the medication on a PD patient. Interview with Michael J. Fox on NBC's Today Show
- Pope John Paul II
- Muhammad Ali
- Johnny Cash
References
- Ogden, Jenni A. (1996). Fractured Minds. Oxford: New York.
- Stirling, John. (2002). Introducing Neuropsychology. Psychology Press: New York.
- National Parkinson Foundation
