What Is Parkinson's Disease?
Parkinson's disease is a common condition of the brain that typically begins in the middle to later part of life. It is a progressive condition, meaning that it continues to get worse with time. There is currently no cure for Parkinson's disease, nor is there a way to prevent it
(see Prevention of Parkinson's Disease).
Parkinson's disease has probably existed for thousands of years. Its symptoms and potential therapies were mentioned in the Ayurveda (the system of medicine practiced in India as early as 5000 B.C.) and in the first Chinese medical text (Nei Jing), which appeared 2,500 years ago.
What Causes Parkinson's Disease?
Parkinson's disease results from the loss of brain cells in a region of the brain that controls movement. This loss creates a shortage of dopamine, which is a chemical in the brain called a neurotransmitter. This loss of dopamine results in the problems with movement that are characteristic of Parkinson's disease.
Although there are many theories as to why these brain cells die, no actual Parkinson's disease cause has ever been proven.
Current theories regarding the possible cause or causes of Parkinson's disease include:
- Environmental factors
- Genetic factors
- Free radicals
- Normal age-related wearing down
- A combination of some or all of these theories.
Symptoms of Parkinson's Disease
In its fully developed form, Parkinson's disease is easy to recognize. However, Parkinson's and its symptoms are often subtle in the beginning and tend to progress slowly. So
early symptoms of Parkinson's disease may last a long time before the more classic and obvious symptoms appear.
Often, the first noticeable sign of Parkinson's disease is a tremor. This characteristic symptom often begins on one side of the body, frequently in one hand. It is often more obvious during rest, and improves with activity. It may also affect the arms, legs, feet, jaw, face, eyelids, and tongue. After months or years, the tremor may become present in all limbs and on both sides of the body.
Other common symptoms of Parkinson's disease include:
- Stiffness in the limbs and trunk
- Slow movement
- Loss of spontaneous and automatic movement (such as swinging the arms when walking)
- A shuffling gait
- A stooped posture
- Problems with coordination and balance
- Fixed facial expressions
- Speaking in a soft voice.
As these Parkinson's disease symptoms become more pronounced, people may have difficulty walking, talking, or completing other simple tasks.
Parkinson's is both chronic, meaning it persists over a long time, and progressive, meaning its symptoms grow worse over time. It is not contagious, nor is it usually inherited -- that is, it does not pass directly from one family member or generation to the next.
Occasionally, Parkinson's disease also causes:
Making a Parkinson's Disease Diagnosis
Parkinson's disease is usually diagnosed by a neurologist (a doctor who specializes in conditions of the nervous system), who can evaluate symptoms and their severity. This disease may be difficult for healthcare providers to diagnose, because early symptoms may be vague and they can mimic other conditions or even be dismissed as normal aging. Also, there is currently no test that can clearly identify the disease.
People with suspected Parkinson's disease are sometimes given
Parkinson's disease medications to see if they respond. Other tests, such as brain scans, can help healthcare providers decide if a person has true Parkinson's disease or some other condition that resembles it.
Several medical conditions can share similar symptoms with Parkinson's disease, especially during the early stages. Your healthcare provider will consider these before making a Parkinson's disease diagnosis
(see Diagnosing Parkinson's Disease for more information).
Parkinson's disease is the most common form of
parkinsonism, the name for a group of disorders with similar features. These conditions share similar symptoms, and all are the result of the loss of dopamine-producing brain cells.
Parkinson's disease is also called primary parkinsonism or idiopathic Parkinson's disease (idiopathic is a term used to describe a condition for which no cause has yet been found). In the other forms of parkinsonism, either the cause is known or suspected, or the condition occurs as a secondary effect of another, primary neurological disorder.
Parkinson's Disease Stages
Once diagnosed, several rating systems are in place to determine the stage of Parkinson's disease. A widely used scale categorizes people with the disease into one of five stages. These stages can help healthcare providers decide what treatment to recommend. They can also help families gain a better understanding of how Parkinson's disease progresses. The overall effect and severity of these symptoms increases with each of these stages.
Healthcare providers may also describe Parkinson's disease stages as early, moderate, and advanced.
Treating Parkinson's Disease
In the early 1960s, researchers identified a fundamental brain defect that is a hallmark of Parkinson's disease -- a loss of brain cells that produce a chemical (dopamine) that helps direct muscle activity. This discovery pointed to the first successful treatment for Parkinson's disease and suggested ways of devising new and even more effective therapies.
However, there is no cure for Parkinson's or treatment that has been shown to slow down or stop the disease's progression. But there is treatment for Parkinson's disease that provides dramatic relief from the symptoms.
Some of these treatments for Parkinson's disease can include:
Not everyone who is diagnosed with Parkinson's disease will immediately require medicine. Many people are only mildly affected and do not require medications for several years after the initial diagnosis.
When Parkinson's treatment does become necessary, healthcare providers often begin with one or more of the less powerful medications for Parkinson's disease. This includes such drugs as:
This allows healthcare providers to save the most powerful treatment (specifically, levodopa) for the time when people need it the most.
When
Parkinson's disease symptoms grow severe, healthcare providers usually prescribe levodopa combined with
carbidopa.
Carbidopa-levodopa products are available as the brand-name medicines
Sinemet®, Sinemet
® CR,
Parcopa® or as a generic. Carbidopa is used with levodopa because it delays the conversion of levodopa into dopamine until it reaches the brain. Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply of this neurotransmitter.
There are a number of other medicines approved for treating Parkinson's disease symptoms. These can be given alone or in combination with levodopa in order to treat symptoms.
History of Parkinson's Disease
Parkinson's disease was first described in 1817 by James Parkinson, a British physician who published a paper on what he called "the shaking palsy." In this paper, he set forth the major symptoms of the disease that would later bear his name. For the next century and a half, scientists pursued the causes and treatment of Parkinson's disease. They defined its range of symptoms, distribution among the population, and prospects for cure.
How Many People Does Parkinson's Disease Affect?
In the United States, at least 500,000 people are believed to suffer from Parkinson's and about 50,000 new cases are reported each year. These
Parkinson's disease statistics are expected to increase as the average age of the population increases. Parkinson's disease appears to be slightly more common in men than women.
The average onset of Parkinson's occurs around age 60. The disease becomes more common with advancing age. Though Parkinson's is found most often in people over 50, as many as 10 percent of people with the condition are under the age of 40. These people are afflicted with what's called "young-onset" Parkinson's disease.
Parkinson's is found all over the world. The rates vary from country to country, but it is not clear whether this reflects true ethnic and/or geographic differences or discrepancies in the methods of data collection.
Microscopic brain structures, called Lewy bodies, which can only be seen during an autopsy, are regarded as a hallmark of classical Parkinson's disease. In one study, autopsies uncovered Lewy bodies in a surprising number of older people without diagnosed Parkinson's, including:
- Eight percent of people over 50
- Almost 13 percent of people over 70
- Almost 16 percent of those over 80.
As a result, some experts believe Parkinson's disease is something of an "iceberg phenomenon," lurking undetected in as many as 20 people for each known person with Parkinson's. A few
Parkinson's disease research scientists believe that almost everyone would develop Parkinson's eventually if they lived long enough.
Society pays an enormous price for Parkinson's disease. According to the National Parkinson Foundation, each person spends an average of $2,500 a year for medications. After factoring in office visits, Social Security payments, nursing home expenditures, and lost income, the total national cost is estimated to exceed $5.6 billion annually.
