Parkinson's Disease Definition and Overview
Parkinson's disease (PD) is an age-related progressive deterioration of certain nerve systems in the brain, which affects movement, balance, and muscle control.
- Parkinson's disease is one of the most common movement disorders, affecting about 1% of people older than 60 years. Parkinson's disease is about 1.5 times more common in men than in women, and it becomes more likely to occur in people as they age. Parkinson's disease is not a hereditary disease.
- The average age of onset is about 60 years. Onset before age 40 years is relatively uncommon, but the much-publicized diagnosis of actor Michael J. Fox shows that younger people are also vulnerable.
- In Parkinson's disease, brain cells deteriorate (or degenerate) in an area of the brain called the substantia nigra. From the substantia nigra, specific nerve cell tracts connect to another part of the brain called the corpus striatum, where the neurotransmitter (a chemical messenger in the brain) called dopamine is released. Dopamine is an important neurotransmitter and alterations in its concentration can lead to the different medical problems seen in Parkinson's disease.
- The loss of these specific brain cells and decline in dopamine concentration are key steps that lead to the signs and symptoms of Parkinson's disease as well as are the target for treatments of Parkinson's disease. However, the biological, chemical, and genetic mechanisms responsible for the brain cell loss have not been identified with certainty.
Medically Reviewed by a Doctor on 4/23/2015
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