Bodily movements are regulated by a portion of the brain called the basal ganglia, whose cells require a proper balance of two substances called dopamine and acetylcholine, both involved in the transmission of nerve impulses. In Parkinson's, cells that produce dopamine begin to degenerate, throwing off the balance of these two neurotransmitters.
Researchers believe that genetics sometimes plays a role in the cellular breakdown. In rare instances, Parkinson's disease may be caused by a viral infection or by exposure to environmental toxins such as pesticides, carbon monoxide, or the metal manganese. But in the great majority of Parkinson's cases, the cause is unknown.
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