The Facts about Parkinson’s Disease

Parkinson's disease belongs to a group of conditions called motor system disorders. The four primary symptoms are tremor or trembling in hands, arms, legs, jaw, and face; rigidity or stiffness of the limbs and trunk; bradykinesia or slowness of movement; and postural instability or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks.

The disease is both chronic, meaning it persists over a long period of 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.

People with Parkinson's disease often show reduced facial expressions and speak in a soft voice. Various other symptoms might accompany Parkinson's disease; some are minor while others are more bothersome. They include depression or other emotional changes, difficulty swallowing and chewing, speech changes (speaking too softly or in a monotone, hesitation, repeating, slurring, or speaking too fast), urinary problems or constipation, skin changes (oiliness, dryness or excessive sweating) and sleep problems.

Many of these can be treated with appropriate medication or physical therapy. No one can predict which symptoms will affect an individual patient, and the intensity of the symptoms also varies from person to person. None of these symptoms is fatal, although swallowing problems can cause choking.

Incidence
In the United States, at least 500,000 people are believed to suffer from Parkinson's disease, and about 50,000 new cases are reported annually. These figures are expected to increase as the average age of the population increases. Getting an accurate count of the number of cases may be impossible however, because many people in the early stages of the disease assume their symptoms are the result of normal aging and do not seek help from a physician. Also, diagnosis is sometimes difficult and uncertain because other conditions may produce some of the symptoms of Parkinson's disease.

The disorder appears to be slightly more common in men than women. The average age of onset is about 60; the incidence increases with advancing age. The rates are very low in people under 40 and rise among people in their 70s and 80s. Parkinson's disease 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 data collection.

Cause Remains Unknown
Parkinson's disease is the most common form of parkinsonism, the name for a group of disorders with similar features. These disorders share the four primary symptoms described in the first paragraph, and all are the result of the loss of brain cells that produce dopamine, a chemical messenger that transmits impulses from one nerve cell to another. Loss of dopamine causes the nerve cells to fire out of control, leaving patients unable to direct or control their movements in a normal manner.

Although there are many theories about the cause of Parkinson's disease, none has ever been proved. Researchers have reported families with apparently inherited Parkinson's for more than a century. However, until recently, the prevailing theory held that one or more environmental factors caused the disease. Severe Parkinson's-like symptoms have been described in people who took an illegal drug contaminated with a chemical known as MPTP and in people who had a severe form of influenza during an epidemic in the early 1900s. Recent studies of twins and families with Parkinson's have suggested that some people have an inherited susceptibility to the disease that may be influenced by environmental factors.

Diagnosis
Parkinson's disease is usually diagnosed by a neurologist who can evaluate symptoms and their severity. There is no test that can clearly identify the disease. Sometimes people with suspected Parkinson's disease are given anti-Parkinson's drugs to see if they respond. Other tests, such as brain scans, can help doctors decide if a patient has true Parkinson's disease or some other disorder that resembles it.

Even for an experienced neurologist, making an accurate diagnosis in the early stages of Parkinson's disease can be difficult. There are, as yet, no sophisticated blood or laboratory tests available to diagnose the disease. The physician may need to observe the patient for some time until it is apparent that the tremor is consistently present and is joined by one or more of the other classic symptoms. Since other forms of parkinsonism have similar features but require different treatments, making a precise diagnosis as soon as possible is essential for starting a patient on proper medication.

Treatment
There is no cure for Parkinson's disease, but a variety of medications provide dramatic relief from the symptoms. 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. L-dopa is a simple chemical found naturally in plants and animals. Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply.

Levodopa's success in treating the major symptoms of Parkinson's disease is a triumph of modern medicine. First introduced in the 1960s, it delays the onset of debilitating symptoms and allows the majority of parkinsonian patients – who would otherwise be very disabled – to extend the period of time in which they can lead relatively normal, productive lives. But levodopa is not a perfect drug. Although it helps at least three-quarters of parkinsonian cases, not all symptoms respond equally to the drug. Fortunately, physicians have other treatment choices for particular symptoms or stages of the disease.

When recommending a course of treatment, the physician determines how much the symptoms disrupt the patient's life and then tailors therapy to the person's particular condition. Since no two patients will react the same way to a given drug, it may take time and patience to get the dose just right. Even then, symptoms may not be completely alleviated. In the early stages of Parkinson's disease, physicians often begin treatment with one or a combination of the less powerful, saving the most powerful treatment, specifically levodopa, for the time when patients need it most.

Treating Parkinson's disease with surgery was once a common practice, but after the discovery of levodopa, surgery was restricted to only a few cases. Currently, surgery is reserved for patients who have failed to respond satisfactorily to drugs. In patients who are very severely affected, a kind of brain surgery known as pallidotomy has reportedly been effective in reducing symptoms. 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 identify substances that will prevent dopamine-producing brain cells from dying.

Coping
One of the most demoralizing aspects of the disease is how completely the patient's world changes. The most basic daily routines may be affected — from socializing with friends and enjoying normal and congenial relationships with family members to earning a living and taking care of a home. Faced with a very different life, people need encouragement to remain as active and involved as possible. That's when support groups can be of particular value to parkinsonian patients, their families, and their caregivers.

Because movements are affected in Parkinson's disease, exercising may help people improve their mobility. Some doctors prescribe physical therapy or muscle-strengthening exercises to tone muscles and to put underused and rigid muscles through a full range of motion. Exercises will not stop disease progression, but they may improve body strength so that the person is less disabled. Exercises also improve balance and can strengthen certain muscles so that people can speak and swallow better. Exercises can also improve the emotional well-being of parkinsonian patients by giving them a feeling of accomplishment. Although structured exercise programs help many patients, more general physical activity, such as walking, gardening, swimming, calisthenics, and using exercise machines, is also beneficial.

Research
As yet, there is no way to predict or prevent the disease. However, researchers are now looking for a biomarker – a biochemical abnormality that all patients with Parkinson's disease might share – that could be picked up by screening techniques or by a simple chemical test given to people who do not have any parkinsonian symptoms.

Positron emission tomography (PET) scanning may lead to important advances in our knowledge about Parkinson's disease. PET scans of the brain produce pictures of chemical changes as they occur in the living brain. Using PET, research scientists can study the brain's dopamine receptors (the sites on nerve cells that bind with dopamine) to determine if the loss of dopamine activity follows or precedes degeneration of the neurons that make this chemical. This information could help scientists better understand the disease process and may potentially lead to improved treatments.

Parkinson's disease may be one of the most baffling and complex of the neurological disorders. Its cause remains a mystery but research in this area is active, with new and intriguing findings constantly being reported. In the last decade, research has laid the groundwork for many of today's promising new clinical trials, technologies, and drug treatments. Scientists, physicians, and patients hope that today's progress means tomorrow's cure and prevention.

This article has been adapted from information provided by the National Institute of Neurological Disorders and Stroke (NINDS). For more information, visit www.ninds.nih.gov, call 800-352-9424, or write to the NINDS Brain Resources and Information Network (BRAIN) at P.O. Box 5801, Bethesda, MD 20824.

For more information on this topic, see the HealthLink articles Locating the Timekeeping Centers of the Brain and Movement Disorders Program: “Our goal is to help patients maintain a normal life.”

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.