Parkinson's disease (PD) primarily affects nerve cells (neurons) in the deep parts of the brain (substantia nigra) that produce a chemical called dopamine (a neurotransmitter). Dopamine plays an important role in controlling muscle movement. Patients often experience trembling, muscle rigidity, slowed motion, smaller handwriting, drooling, difficulty walking, and problems with balance and coordination. Impaired speech and swallowing difficulty is seen in later stages of the disease. Neurons that produce other brain chemicals such as serotonin, noradrenalin, and acetylcholine can be affected as well. Depending on the severity of such involvement, memory and attention problems, dementia, anxiety or depression, or problems with autonomic functions such as blood pressure, urination, and bowel movements can be observed.
The cause of Parkinson's disease has not been found yet. Heredity and environmental factors such as exposure to pesticides and herbicides are believed to play a role. In very small groups of patients, distinct genetic changes have been identified.
Nearly one million Americans currently live with Parkinson's and approximately 50,000 to 60,000 more are diagnosed with Parkinson's disease every year. These symptoms generally develop after age 50, although the disease affects a small percentage of younger people below age 40 as well. The diagnosis of Parkinson's disease is a clinical one, meaning that it is based on your medical history, observations of your symptoms, and a neurologic examination. There are no confirmatory tests. Diagnostic tests are usually ordered when the diagnosis is in doubt so that other causes for the patient's problems can be ruled out. Symptoms become worse over time, and the course varies widely from individual to individual. Some conditions may resemble Parkinson's disease at the beginning, but have many other features and usually do not respond to treatment. These are called Parkinson's-plus syndromes. They have a worse prognosis than Parkinson's disease. Examples include progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophy.
There is no standard treatment, and it should be tailored to the patient's age, general health, mental function, and ability to tolerate the medications. With the progression of the disease, changes to lifestyle and home environment may be needed. Treatment is symptomatic, meaning that our current means do not cure or stop the progression of Parkinson's disease, but ease the symptoms. Medications are aimed to restore dopamine levels in the brain. Levodopa, commonly known as L-dopa, is used for dopamine synthesis. It is usually administered with carbidopa or benzeraside to increase its passage into the brain and diminish side effects such as nausea. Dopamine agonists (bromocriptine, pergolide, pramipexole, and ropinirole) imitate dopamine in the brain. Tolcapone and entacapone are used to prolong the action of levodopa. Other agents include selegiline, amantadine, and anticholinergic medications. These medications may have various side effects such as nausea, vomiting, sleepiness, lightheadness, confusion, and hallucinations, to name a few. The effectiveness of these medications diminishes over time. There are many other medications in various stages of development. When patients develop symptoms that are not movement related, such as dementia, depression, hallucinations, or constipation, treatment aimed at these symptoms is used. Consultations from psychiatry, internal medicine, urology, physical therapy, occupational therapy, and speech pathology may be needed.
Surgical treatment of Parkinson's disease is also symptomatic and includes either creating small lesions (pallidotomy, thalamotomy) or deep brain stimulation (DBS) in deep parts of the brain such as subthalamic nucleus, globus pallidus, and thalamus. DBS involves implanting a brain stimulator, similar to a heart pacemaker. Patient selection is very important, and good candidates have a well-established diagnosis of Parkinson's disease, are usually relatively young, otherwise healthy, not demented, and still responding to Parkinson's Disease medications, but with involuntary movements and large fluctuations in their response to levodopa during the day. It should be noted that some of these procedures are considered experimental, and patients should inquire about their current status with their treating physician. Fetal cell transplantation and stem cell therapy are at various experimental stages.
This material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Department of Neurology, Carver College of Medicine, or the University of Iowa. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history. Please do not send personal inquiries.
See related Patient Textbooks about Neurology.
See related Patient Topics Brain and Nervous System, Neurology, Parkinson's Disease or Seniors' Health.
See related Provider Textbooks about Neurology.
See related Provider Topics Brain and Nervous System, Neurology, Parkinson's Disease or Seniors' Health.
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