Parkinson's disease is a disorder of certain nerve cells in a part of the brain that produces dopamine (chemical messenger the brain uses to help direct and control body movement). These 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). It progresses gradually over 10 to 15 years. This results in more and more disability. In five to 10 percent of cases, Parkinson's disease develops during a person's 20s or 30s. This is called early-onset Parkinson's disease.
Classic symptoms are shaking, stiff muscles and slow movement. People with an advanced case also may have stooped posture, a fixed look on the face, 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 is worse when the person is awake but not moving around. Emotional and physical stress tends to make the tremor worse. Sleep, complete relaxation and intentional movement or action usually reduce or stop the tremor. Up to 25 percent of people with Parkinson's disease do not have tremor.
The muscles of the legs, face, neck or other parts of the body may go rigid. Another common early sign of the 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:
- Less dexterity and coordination. Changes in handwriting are common, with writing becoming smaller. Athletic skills decline, and daily activities (such as dressing and eating) become harder.
- Weakness of face and throat muscles. Talking and swallowing may become more difficult. Choking, coughing or drooling may occur. Speech becomes softer and monotonous. Loss of movement in the muscles in the face, including around the eyes, can cause a fixed, vacant look on the face.
- 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. These include more 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 can result from anxiety, depression or a feeling of restlessness. Patients may not be able to sleep well. They cannot easily turn over or change position in bed.
- A person may slowly become more dependent, fearful, indecisive and passive. The person may talk less often, withdraw from people and be inactive unless encouraged to move about. Depression is very common with this disease. It can be caused by chemical changes in the brain, or it can be a reaction to having a disabling disease. Depression often improves with proper treatment.
- Up to one-third of patients may develop dementia and confusion. This is similar to Alzheimer's disease. Depression can add more memory loss and confusion. These symptoms, as well as hallucinations (seeing or hearing things that aren't really there), and vivid dreams may be caused by drugs taken to treat the disease.
Although some forms are genetic, the causes for most forms of Parkinson's disease are unknown. Studies of environmental and inherited factors are starting to offer clues.
Diagnosis is based mostly on the patient's medical history and an examination of the nervous system.
There are no lab tests to diagnose Parkinson's disease. If symptoms and the doctor's findings are not entirely typical of the disease, other tests may be done. For instance, blood tests may be done to check for abnormal thyroid hormone levels, liver damage or other problems. Magnetic resonance imaging may be used to check for stroke or brain tumor. A PET imaging scan may show low levels of dopamine in the brain - a key sign of the disease.
Once Parkinson's is considered very likely, taking a specific medication for a short time may help confirm the diagnosis. About 90% of people respond to medication. If symptoms improve while the patient takes the medication, Parkinson's disease is confirmed.
There is no early-detection screening test for Parkinson's disease at this time.
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 the person's daily activities. The medication is based on the stage of the disease and the patient's symptoms. Exercise, physical therapy and occupational therapy can also help maintain strength, movement and independence.
Treatment is different for every person. Treatment needs may change as the disease goes on. As the individual's medical condition changes, 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.
