Parkinson's Disease

Parkinson's disease is a disorder of nerve cells in a part of the brain that produces dopamine. Dopamine is a chemical messenger that the brain uses to help direct and control body movement. In Parkinson's disease, these dopamine-producing nerve cells break down, dopamine levels drop and brain signals that direct movement become abnormal.

Parkinson's disease usually begins in middle or late life (after age 50) and progresses gradually over 10 to 15 years, resulting in more and more disability. In 5 to 10% of cases, Parkinson's disease develops during a person's 20s or 30s. This is called early-onset Parkinson's disease.

The classic symptoms of Parkinson's disease are shaking, stiff muscles and slow movement. A person with advanced Parkinson's disease may have stooped posture, a fixed facial expression, speech problems or problems with balance or walking. They may also experience a loss of intellect. Tremor (shaking) usually is the first symptom people notice. Unlike most other tremors, the "resting" tremor of Parkinson's disease is most severe when the person is awake but not moving around. Emotional and physical stress tend to make the tremor worse. Sleep, complete relaxation and intentional movement or action usually reduce or stop the tremor. Up to 25% of people with Parkinson's disease do not have tremor.

The patient may also experience rigidity of the muscles of the legs, face, neck or other parts of the body. Another common early sign of Parkinson's disease is a reduced swing of the arm on one side when the person is walking. Parkinson's disease can cause a variety of other disabilities, including:

Decreased dexterity and coordination. Changes in handwriting are common, with writing becoming smaller. Athletic skills decline, and daily activities (such as dressing and eating) become more difficult.
Weakness of face and throat muscles. Talking and swallowing may become more difficult, and choking, coughing or drooling may occur. Speech becomes softer and monotonous. Loss of movement in the muscles in the face, including those around the eyes, can cause a fixed, vacant facial expression.
Cramps in the muscles and joints
Oily skin or increased dandruff
Constipation and problems controlling or starting urination
Problems with involuntary or automatic body functions, such as increased sweating, low blood pressure when the person stands up and problems with sexual function
"Freezing," a sudden, brief inability to move, most often affects walking.
Problems falling asleep or staying asleep (insomnia) can result from anxiety, depression or physical restlessness. The person may not be able to sleep well because he or she cannot easily turn over or change position in bed.
A person with Parkinson's disease slowly may become more dependent, fearful, indecisive and passive. The person may talk less often than he or she used to, withdraw from family and friends and remain inactive unless encouraged to move about. Depression is very common in people with this disease and can be caused by chemical changes in the brain or can be a reaction to having a disabling disease. Depression often improves with proper treatment.
Up to one-third of Parkinson's patients may eventually develop dementia and confusion, similar to Alzheimer's disease. Depression can further contribute to memory loss and confusion. These symptoms, as well as hallucinations (seeing or hearing things that are not really there) and vivid dreams may sometimes be caused by medications taken to treat Parkinson's disease.

Causes

Although some forms of Parkinson's disease are genetic, the causes for most forms of are unknown. However, studies of environmental and inherited (genetic) factors are beginning to provide some clues. The Neurogenetics, Neurofibromatosis and Ataxia Center and Rose Moss Laboratory at Cedars-Sinai specialize in the diagnosis and research of inherited forms.

Diagnosis

Diagnosis is based mostly on the patient's medical history and a thorough examination of the nervous system.
There are no lab tests to diagnose Parkinson's disease. If symptoms and the doctor's findings during the exam are not entirely typical of Parkinson's disease, certain tests may be done to help diagnose other conditions. For instance, blood tests may be done to check for abnormal thyroid hormone levels, liver damage or other problems. A magnetic resonance imaging (MRI) scan may be used to check for signs of a stroke or brain tumor.

Another type of imaging, called positron emission tomography (PET), may detect low levels of dopamine in the brain, a key sign of Parkinson's disease. Once a diagnosis of Parkinson's disease is considered very likely, a short course of a medication, such as levodopa, may help confirm the diagnosis. About 90% of people with Parkinson's disease respond to levodopa or other medication. If symptoms improve while the patient takes the medication, Parkinson's disease is essentially confirmed. There is no early-detection screening test for Parkinson's disease at this time.

Treatment

No known treatment can halt or reverse the breakdown of nerve cells that causes Parkinson's disease. However, medication can relieve many symptoms. Surgery to treat symptoms also can be effective in a small number of people.

Medication is usually started when symptoms begin to interfere with daily activities and is based on the stage of the disease and the specific symptoms. Additional treatment methods (exercise, physical therapy and occupational therapy) can be helpful at all stages of Parkinson's disease to help maintain strength, mobility and independence.
Treatment is different for every person, and treatment needs may change as the disease progresses. As the individual's medical condition changes, regular adjustments in treatment are needed to balance quality-of-life issues and side effects of treatment.

Emotional support and education about the illness should begin early and continue throughout the course of the disease. This can be provided by the doctor, other health professionals or Parkinson's disease support groups.