Parkinson's disease is a neurological disorder that targets brain cells that control movement. Symptoms include tremors, stiffness and poor balance, as well as depression or dementia. Some patients experience impairments of the "autonomic" nervous system, the part of the nervous system that helps control blood pressure as well as the bowel and bladder.
The disease, which affects about 1 million people in the United States, targets neurons that produce an important chemical called dopamine. Dopamine is a chemical messenger that transmits signals within the brain. Normally, dopamine operates in a delicate balance with other neurotransmitters to help coordinate the millions of nerve and muscle cells involved in movement. Because Parkinson's patients have a loss of dopamine-producing cells in the brain, the coordination among nerve and muscle cells is disrupted.
The cause of the disease is unknown.
Parkinson's generally progresses slowly, sometimes taking years for symptoms to appear. The disease usually strikes adults over age 50, although it has been diagnosed as early as age 20. About 15 percent of Parkinson's patients have a family history of the disease.
Because it develops gradually, most people have many years of productive living after being diagnosed.
Some of the first symptoms commonly experienced with Parkinson's include the following:
A diagnosis for this disease generally includes an assessment of symptoms and a series of tests. There is no single test to clearly identify the disease.
Tests administered may include:
The imaging tests are generally quick and painless. They use diagnostic cameras and recording devices to produce images of organs and tissues inside your body.
If you've been diagnosed with Parkinson's already, these tests can help determine if you have the classic form or an atypical form of the disease.
If you doctor suspects you have Parkinson's disease, he or she may prescribe anti-Parkinson's drugs to see if you respond.
Medications can provide dramatic relief from Parkinson's symptoms, but no drug can stop the progression of the disease. In some cases, surgery is an option. Some doctors recommend physical therapy or muscle strengthening. For many patients, a combination of these approaches works best.
Levodopa, combined with another drug called carbidopa or Sinemet, is the mainstay of Parkinson's therapy. Levodopa is rapidly converted into dopamine by the enzyme dopa decarboxylase (DDC), which is present in the central and peripheral nervous systems. Much of levodopa is metabolized before it reaches the brain.
Because these drugs are known to cause side effects and can become ineffective after prolonged periods of use, other drugs, such as dopamine agonists, amantadine, COMT inhibitors and anticholinergic medications also are used to treat Parkinson's disease.
Reviewed by health care specialists at UCSF Medical Center.