Parkinson's Disease (cont.)
IN THIS ARTICLE
Low levels of dopamine, a brain chemical (neurotransmitter) involved in controlling movement, cause symptoms of Parkinson's disease. The shortage of this brain chemical occurs when nerve cells in a part of the brain (substantia nigra) that produces dopamine fail and deteriorate. The exact cause of this deterioration is not known.
The links between Parkinson's disease and factors such as genetics, aging, toxins in the environment, and free radicals are all under investigation. Although these studies are beginning to provide some answers, experts do not know the exact cause of the disease.
Studies are ongoing to determine whether there is a genetic cause of Parkinson's disease. Only a small percentage of people with Parkinson's disease have a parent, brother, or sister who has the disease. But abnormal genes do seem to be a factor in a few families where early-onset Parkinson's disease is common.
The type and severity of symptoms experienced by a person with Parkinson's disease vary with each individual and the stage of Parkinson's disease. Symptoms that develop in the early stages of the disease in one person may not develop until later—or not at all—in another person.
The most common symptoms include:
Tremor is often the first symptom that people with Parkinson's disease or their family members notice. Initially, the tremor may appear in just one arm or leg or only on one side of the body. The tremor also may affect the chin, lips, and tongue. As the disease progresses, the tremor may spread to both sides of the body. But in some cases the tremor remains on just one side.
Emotional and physical stress tend to make the tremor more noticeable. Sleep, complete relaxation, and intentional movement or action usually reduce or stop the tremor.
Although tremor is one of the most common signs of Parkinson's disease, not everyone with tremor has Parkinson's disease. Unlike tremor caused by Parkinson's disease, tremor caused by other conditions gets better when your arm or hand is not moving and gets worse when you try to move it. The most common cause of non-Parkinson's tremor is essential tremor, a treatable condition that is often wrongly diagnosed as Parkinson's disease.
Parkinson's disease can cause many other symptoms. These can be disabling and may include:
Problems with sleep, mood, and thought also are common in people who have Parkinson's disease.
There are many other conditions with similar symptoms. Some of these may be reversible.
eMedicineHealth Medical Reference from Healthwise
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