Cause
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; however,
abnormal
genes do seem to be a factor in a few families where
early-onset Parkinson's disease is common.