Why
we do what we do:
Drive around the World was founded as a creative response
to the helplessness we felt after learning that our families had been stricken
by Parkinson’s disease. Coincidently, Expedition Leader, Nick Baggarly’s sister
and team member, Todd Borgie's father were diagnosed shortly after the team
returned from the last expedition in which we encircled the globe via lines of
Latitude (Beijing to San Francisco).
Although we had seen this disease before, nothing makes it more personal
than seeing a family member grapple with its debilitating effects. This disease
not only impacts its target victims, but also affects people all around them. I
think we were all stricken with an overwhelming feeling of helplessness, “What
can we do?” We aren’t scientists or doctors! Are we doomed to see this disease
take it natural destructive course? It
was at this point that, team member Chanda Baggarly, suggested the idea of a
drive-a-thon. This was a perfect opportunity to use something we knew how to do
and something we loved to do to benefit others. A team was selected, many
members having personal connections to Parkinson’s, and now we are on our way.
Everyone is invited and encouraged to help us reach our
goal of raising over a million dollars to fight this debilitating disease.
Every dollar spent on a cure brings us closer to our final destination, a cure
for Parkinson’s disease. To donate, follow the donation links on the home page.
To obtain information on how to hand out pledge brochures please send a note to
info@drivearoundtheworld.com
Famous people who have had or still have Parkinson’s Disease
|
I |
|
INTRODUCTION |
Parkinson Disease, disorder of the nervous system that
affects muscle control. Marked by trembling of the arms and legs, muscular rigidity,
and poor balance, Parkinson disease is slowly progressive, worsening over time.
Eventually symptoms may cause problems with walking or talking and, in some
people, difficulty thinking. Physicians do not know how to cure Parkinson
disease, but drug therapy or surgery may alleviate some of the most troubling
symptoms. The disease is named for British physician James Parkinson, who first
described it in 1817. In a report describing six patients, Parkinson called the
disorder paralysis agitans, Latin words that mean “shaking palsy.”
The National Parkinson
Foundation based in Miami, Florida, estimates that 1.5 million people in the
United States are affected with Parkinson disease, although estimates are
difficult to make because symptoms of the disease are often mistaken for the
normal effects of aging or are attributed to other diseases. Parkinson disease
occurs in people all over the world, with the incidence in men slightly higher
than in women. Caucasians have a higher incidence of the disease than people of
other races. People most commonly develop Parkinson disease around the age of
60, and the incidence rises with age. However, at least 10 percent of cases
occur in people under age 40, and a rare form of the disease affects teenagers.
Parkinson disease may
initially be mistaken for one or more of a group of nervous system diseases
collectively known as parkinsonism (also known as Parkinson Plus diseases), all
of which have certain symptoms in common. Unlike most cases of Parkinson disease,
most forms of parkinsonism develop from an identifiable cause, such as exposure
to certain chemicals, drugs, or viruses. Often initially diagnosed as Parkinson
disease, parkinsonism diseases do not respond to the drug therapies that treat
Parkinson disease symptoms effectively. Physicians have also noted that the
changes in the nervous system in people who have parkinsonism differ from those
in patients who have Parkinson disease.
|
II |
|
CAUSE |
Parkinson disease develops
as a part of the brain known as the substantia nigra degenerates. The
substantia nigra is located in the midbrain, halfway between the cerebral
cortex and the spinal cord. In healthy people, the substantia nigra contains
certain nerve cells, called nigral cells, that produce the chemical dopamine.
Dopamine travels along nerve cell pathways from the substantia nigra to another
region of the brain, called the striatum. In the striatum, dopamine activates
nerve cells that coordinate normal muscle activity. In people with Parkinson
disease, nigral cells deteriorate and die at an accelerated rate, and the loss
of these cells reduces the supply of dopamine to the striatum. Without adequate
dopamine, nerve cells of the striatum activate improperly, impairing a person’s
ability to control movement.
A study published in 2000
found that people with Parkinson disease have a decreased number of nerve
fibers in the heart. These results suggest that the disease affects nerves in
organs outside the brain and may explain symptoms common in people with
Parkinson disease, such as a drop in blood pressure when a person stands up,
constipation, and difficulty urinating.
Scientists do not understand
the mechanisms underlying nerve cell death in Parkinson disease. Most
researchers believe that Parkinson disease results from a combination of
factors involving genetics, environmental agents, and abnormalities in cellular
processes.
|
A |
|
Genetics |
Studies suggest that genetic
makeup may place a person at higher risk for developing Parkinson disease.
Fifteen percent of people with Parkinson disease have one or more family
members who also have the disease. In studies of families in which members from
at least three generations have been diagnosed with the disease, scientists
have identified three genes that, when mutated, may play a role in the
development of Parkinson disease. Genes provide coded instructions for the
manufacture of proteins. One of the suspect genes codes for a protein called
alpha-synnuclein. A second gene codes for a protein called parkin, and a third
gene codes for a protein belonging to a family of proteins known as ubiquitin.
Researchers still do not understand the function of alpha-synnuclein, but
parkin and ubiquitin may play a role in cleaning up abnormal deposits of
proteins in the cell. When the genes that produce these proteins are mutated,
parkin and ubiquitin are unable to prevent protein deposits from building up.
The accumulation of these deposits may play a role in nigral cell degeneration.
A recent study among identical
twins also suggests that genetics plays a role in Parkinson disease. In the
study, doctors found that if one twin developed the disease before age 50, the
chance was higher that the other twin would develop the disease if the twins
were identical than it was if they were fraternal. Identical twins have the
same genetic makeup, whereas the genes of fraternal twins are as different as
those of any two siblings. This study suggests that the identical twins both
have a gene that places them at risk for the disease.
|
B |
|
Environmental Factors |
Given the obvious symptoms
associated with Parkinson disease, such as tremor and imbalance, it is odd that
the first description of the disease did not appear until 1817. Some
researchers propose that the disease may have been uncommon before the
Industrial Revolution, the period starting in the 18th century when machinery
began replacing manual labor. The increased number of patients diagnosed with
the disease today may be related to the presence of an environmental toxin
(poisonous chemical) released as a byproduct from machines and other
technology. Alternatively, the higher incidence of the disease may be related
to increasingly longer life spans that enable people to reach an age when the
physical effects of Parkinson disease become more apparent.
Scientists have yet to
identify a particular drug or toxin that causes Parkinson disease, although
they have identified a number of drugs, chemicals, and viruses that cause
diseases that resemble Parkinson disease. The chemical MPTP, a byproduct
created in the synthesis of certain illicit drugs, is linked to the development
of a disease in some drug abusers that closely resembles Parkinson disease.
People who use some common garden pesticides and insecticides also seem to have
a higher incidence of Parkinson disease, although a direct link between
Parkinson disease and these chemicals has not yet been established. Certain
people may develop parkinsonism if they are exposed to other agents, including
carbon monoxide, cyanide, manganese, certain tranquilizers, and some rare
viruses, or if they suffer head injuries or strokes. These parkinsonism
diseases may be initially mistaken for Parkinson disease.
|
C |
|
Free Radicals |
Some research on Parkinson
disease focuses on the role of free radicals, potentially damaging molecules
produced in cells as part of normal cell activity or in response to injury.
Certain free radicals can cause cell damage, injuring the lining of cell
membranes, destroying mitochondria (the cell’s energy-producing
organelles), and triggering cell death. Studies show that dopamine-producing
cells are particularly vulnerable to free-radical destruction. Healthy people
typically have adequate quantities of antioxidants, molecular scavengers that
defend cells from free-radical destruction. Further research may identify
antioxidants that may be useful in blunting the actions of free radicals.
|
III |
|
SYMPTOMS |
Parkinson disease most
notably affects motor control (muscle activity). The disease progresses
differently for each individual—symptoms develop swiftly in some people and
slowly in others. Some Parkinson patients may develop problems that affect
their intellect or ability to reason, or they may suffer from depression or
anxiety.
|
A |
|
Motor Control Problems |
Doctors look for the presence
of four principal symptoms in patients they suspect may have Parkinson disease.
Tremor (the involuntary shaking of limbs) is the major symptom for most people
who have Parkinson disease, although at least a third of people diagnosed with
the disease do not develop this symptom. Tremor typically begins in one hand
but may eventually progress to the other hand, as well as to the arms, legs,
and jaw.
Parkinson disease may
also produce stiffness of the joints, similar to arthritis, and rigidity of the
limbs, in which muscles are tensed, or contracted. This rigidity makes movement
difficult and may contribute to muscle ache and fatigue. Often the rigidity
impairs the small muscles of the hand, making everyday tasks such as buttoning
a shirt or writing difficult.
The most disabling symptom
of Parkinson disease is bradykinesia, which causes slowness in all voluntary
movement and speech and contributes to varied problems, such as a distinctive
shuffling walk and small, cramped handwriting.
Parkinson disease also
causes postural instability, in which a person has difficulty adjusting to
changes in body position. A healthy person who trips and starts to fall is able
to quickly move the trunk and limbs to prevent or ease the fall. But people
with postural instability who trip cannot move fast enough to stop or lessen
their fall. This impaired reflex typically appears as unsteadiness or lack of
balance.
Several secondary symptoms
accompany Parkinson disease, some of which are caused by one or more of these
principal symptoms. For example, many people with Parkinson disease have
difficulty walking, resulting from a combination of bradykinesia and postural
instability. Their walking is marked by short, shuffling steps that sometimes
inadvertently quicken into a short run. Their balance problems may cause them
to stagger forward or backward, giving them a lurching gait. They may have
difficulty turning or stopping as they walk, or sometimes may inexplicably come
to an abrupt stop. Other secondary symptoms include difficulty speaking or
swallowing, an unchanging or masklike facial expression, drooling, dizziness
when moving from a seated to a standing position, difficult urination, and
impotence. Many patients find these secondary symptoms more troubling than the
principal symptoms.
|
B |
|
Mental Disorders |
Around 30 percent of Parkinson
patients develop dementia, a decline in intellect marked by failing memory,
short attention span, and personality changes. Sometimes dementia in Parkinson patients
resembles Alzheimer’s disease, which has a number of the same symptoms,
including certain motor control problems.
Twenty percent of people
with Parkinson disease develop an impairment in which information processing
slows. These people may have difficulty completing formerly simple tasks, such
as balancing a checkbook. This impairment of information processing may be a
forerunner of dementia.
Depression, a condition
marked by hopelessness, low self-esteem, sadness, apathy, and pessimism, occurs
in 40 percent of people with Parkinson disease. A majority of people with
Parkinson disease experience anxiety, which may produce panic attacks—sudden,
overpowering fears, accompanied by breathlessness, sweating, chest pain,
choking, and dizziness (see Panic Disorder). Depression or anxiety may
appear before motor symptoms develop or they may appear as a reaction to motor
symptoms.
Many people with Parkinson
disease also suffer from an inability to sleep at night coupled with daytime
drowsiness. This sleep disturbance may be caused by anxiety or depression, or
it could be a side effect of drugs used to treat Parkinson symptoms. It may
also be a mechanism of the disease—the sleep centers in the brain lie near the
substantia nigra and may be altered by the disease.
|
C |
|
Diseases with Similar Symptoms |
Some medical conditions
initially produce symptoms similar to those of Parkinson disease, but within
two to five years additional symptoms usually develop that enable doctors to
distinguish the conditions from Parkinson disease. For example, a disease
called progressive supranuclear palsy (PSP) produces slowness of movement and
difficulty with balance, resembling Parkinson disease. However, people with PSP
also develop eye movement problems that prevent them from looking up, down, or
sideways without moving the head, and these symptoms can be used to distinguish
this condition from Parkinson disease. Parkinson disease-amyotrophic lateral
sclerosis of Guam is found only among the Chamorro populations of Guam and the
Mariana Islands. This rare disease produces muscle loss throughout the body,
similar to the symptoms of amyotrophic lateral sclerosis, also known as Lou
Gehrig’s disease. Multiple system atrophy (MSA), also known as Shy-Drager
syndrome, displays symptoms similar to those of Parkinson disease. In addition,
MSA affects the autonomic nervous system, producing problems with blood
pressure regulation, heart rate, and bladder function. Parkinson disease also
affects the autonomic nervous system, but the symptoms of MSA are usually more
severe. Another way that these diseases can be distinguished from Parkinson
disease is that they respond poorly to the drugs used to treat Parkinson
disease.
|
IV |
|
DIAGNOSIS |
Diagnosing Parkinson disease
may be difficult, particularly in the early stages of the disease when symptoms
resemble other medical conditions, and misdiagnosis occurs occasionally. No
single laboratory test can diagnose the disease. Blood tests are performed to
eliminate conditions such as a low thyroid, which may result in slowness of
movement. Brain imaging techniques, such as magnetic resonance image (MRI),
positron emission tomography (PET scan), and single photon emission computed
tomography (SPECT), may be used to help doctors exclude other medical
conditions, such as stroke or brain tumors, that produce symptoms similar to
those of Parkinson disease. Doctors quiz patients about their exposure to
drugs, viruses, and environmental toxins to determine if a particular factor
may be causing a parkinsonism disorder. They document the medical history of
the patient’s blood relatives to determine the likelihood of a genetic
predisposition for Parkinson disease or other disorders. And they carefully
observe a patient’s muscular activity over a period of time—as the disease
progresses, motions particular to Parkinson disease become more obvious.
Doctors usually diagnose
Parkinson disease if a patient develops two or more of the principal symptoms,
at least one of which is tremor or bradykinesia. The diagnosis is usually
confirmed if people with suspected Parkinson disease respond well to drug
treatment. Those with parkinsonism disorders or other medical conditions with
similar symptoms typically do not respond to the drugs used in treating
Parkinson disease.
|
V |
|
TREATMENT |
There is no known cure
for Parkinson disease—that is, no treatment that prevents the disease from
progressing. But the symptoms of the disease can be controlled by various drugs
and, in some cases, by surgery.
|
A |
|
Drug Therapy |
Most symptoms of Parkinson
disease arise from a deficiency of dopamine in the brain. But simply giving a
patient a dose of dopamine to restore depleted stores is ineffective because
dopamine cannot pass from the bloodstream to the brain. Drugs that treat
Parkinson disease, known as antiparkinson drugs, use other methods to
temporarily restore dopamine in the brain or closely mimic dopamine’s actions.
In this section, each drug is designated by its generic name, followed by trade
name examples in parentheses.
|
A1 |
|
Levodopa |
The most effective antiparkinson
drug available is levodopa (Laradopa), an oral drug introduced in 1967 that
treats bradykinesia, rigidity, tremor, and difficulty walking. Levodopa’s
structure enables it to enter the brain, where it transforms into dopamine.
When levodopa is taken
alone, however, the body breaks down about 95 percent of the drug into dopamine
before it reaches the brain. Instead of being used by the brain, the dopamine
travels throughout the body, producing side effects, including nausea and
vomiting, before it is broken down, or metabolized, by the liver and other
tissues. Combining levodopa with a drug such as carbidopa enables more levodopa
to enter the brain before it converts into dopamine. Carbidopa/levodopa (Atamet,
Sinemet) lessens rigidity and bradykinesia but is less effective in
treating tremor or balance problems. A similar drug combining carbidopa and
benserazide (Madopar) is available in Canada and Europe.
Carbidopa/levodopa produces
side effects in some people. As many as half of the people who take this drug
for two to five years begin to notice fluctuations in the drug’s effectiveness,
known as an on-off effect. Others develop dyskinesia—involuntary movements such
as jerking or twitching. As Parkinson disease progresses, the effectiveness of
carbidopa/levodopa decreases and patients need higher and more frequent doses
to control their symptoms. Depending upon the severity of symptoms, most
doctors combine carbidopa/levodopa with other drugs to enhance levodopa’s
effects.
|
A2 |
|
Dopamine Agonists |
Dopamine agonists mimic
the action of dopamine by activating nerve cells in the striatum. Dopamine
agonists are increasingly used alone in the early stages of Parkinson disease
in order to lower a patient’s risk of developing the dyskinesia associated with
levodopa therapy. Later in the course of the disease they are more likely to be
combined with carbidopa/levodopa to alleviate that drug’s on-off effects. Side
effects range from nausea, headache, and nasal congestion to nightmares and
hallucinations. Dopamine agonists include pergolide (Permax),
paramipexole (Mirapex), and ropinerole (Requip).
|
A3 |
|
Drugs That Sustain Levodopa’s Effect |
Levodopa does not permanently
restore dopamine in the brain, and the drug may wear off at a certain point
after each dose, diminishing dopamine levels. This may produce intermittent or
discontinuous symptom relief, which may contribute to the on-off effect
experienced by some Parkinson disease patients. A number of drugs are available
that can prolong levodopa’s effectiveness. A sustained or controlled-release
form of carbidopa/levodopa (Sinemet CR) releases a smaller amount of
levodopa over a longer period, extending the time that levodopa is effective.
Some drugs prolong relief
from symptoms by blocking the enzyme catechol-O-methyl transferase (COMT).
These drugs, called COMT inhibitors, delay the break down of levodopa before it
reaches the brain. Taken at the same time as levodopa drugs, COMT
inhibitors—including entacapone (Comtan)—increase the time that levodopa
is effective in the brain and reduce the on-off effect. Working in a similar
manner, drugs that block the action of the enzyme monoamine oxidase-B, called
MAO-B inhibitors, prevent this enzyme from breaking down dopamine in the brain.
Used alone or in combination with carbidopa/levodopa, MAO-B inhibitors,
including selegiline (Eldepryl), do not prolong the actions of levodopa
as well as COMT inhibitors.
|
A4 |
|
Anticholinergics |
When dopamine levels in
the brain drop, another neurotransmitter called acetylcholine becomes
overactive, and the resulting dopamine and acetylcholine imbalance affects
motor skills. Drugs called anticholinergics block the action of acetylcholine.
Typically used in the early stages of the disease when symptoms are mild,
anticholinergic drugs such as trihexiphenidyl (Artane) and biperidine (Akineton)
may lessen tremor and drooling but are not effective in treating bradykinesia
or posture instability.
|
A5 |
|
Amantadine |
The drug amantadine (Symmetrel),
originally developed as an antiviral drug, was later found effective in
treating Parkinson disease. Scientists are unsure how amantadine works—it may
have an anticholinergic effect, and more recent studies show that it also
blocks the action of glutamate, a brain chemical that triggers production of
free radicals. Amantadine is usually used in combination with
carbidopa/levodopa and has been found effective in lessening dyskinesia.
|
B |
|
Surgical Treatment |
In the 1950s and 1960s,
brain surgery was a common method for treating tremor and rigidity in Parkinson
patients, even though the success rate of surgery varied and life-threatening
complications often developed. But surgery fell out of favor with the introduction
in 1967 of levodopa, a safer and more effective treatment alternative. In
recent years the advent of new brain-imaging techniques has improved surgical
precision, and surgery has gained renewed popularity as a treatment for some
people with Parkinson disease who no longer respond to drug therapy.
Two similar surgical procedures
that have been used to treat Parkinson disease involve destroying part of the
brain. To control tremor and rigidity, surgeons perform a thalamotomy to
destroy a small region of the thalamus, a part of the brain that relays signals
coordinating movement. Pallidotomy targets the globus pallidum, a part of the
brain that produces uncontrolled spasmodic movements in Parkinson disease
patients. Doctors now prefer to perform a more effective surgical procedure
called deep brain stimulation. In this procedure, the patient’s head is
immobilized in a halo-like device called a stereotaxic frame. Using an MRI, the
surgeon locates the thalamus, the globus pallidum, or a related region called
the subthalamic nucleus in the brain. After drilling a small hole in the skull,
the surgeon inserts a probe deep into the brain to the target tissue. A short
burst of electricity sent through the probe normalizes the electrical activity
in the brain region, reversing the symptoms of Parkinson disease. This surgery
is reasonably safe, and symptom relief is immediate. But as with any surgery,
risks are involved, including the chance that a stroke may develop.
In a surgical procedure
still in the experimental stage, doctors transplant dopamine-producing cell
tissue into the brain (see Medical Transplantation). In this procedure,
doctors use different sources of cell tissue that make dopamine, including
cells from aborted fetuses and pig embryos. Some studies have shown that these
procedures have alleviated symptoms in some Parkinson patients.
Some doctors are also
investigating the use of human stem cells, immature cells that can be
manipulated to become dopamine-producing cells. Stem cells are hardy and easy
to reproduce—one stem cell can generate billions of copies. The use of stem
cells is controversial because some studies have obtained stem cells from
aborted human embryos. But other sources of human stem cells are available,
including the discarded umbilical cord from healthy babies and the bone marrow
of adults. Using stem cells from these sources may make this treatment more
acceptable. So far studies on the effectiveness of this procedure have provided
conflicting results.
Other doctors are performing
animal experiments in which a gene that produces dopamine is inserted into the
brain cells of an animal with Parkinson disease. The gene causes brain cells to
make dopamine. This procedure, called gene transfer, may one day help alleviate
symptoms or cure Parkinson disease in humans.
http://encarta.msn.com/encyclopedia_761568892/Parkinson_disease.html
Contributed By:
Abraham Lieberman
Microsoft ® Encarta ® Reference Library 2003.
© 1993-2002 Microsoft Corporation. All rights reserved.
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