What Is It?
Parkinson's disease (PD) is a disease of the central nervous system. It causes problems with body motions, including:
Rigidity (muscle stiffness)
Slowed body movements
PD develops when certain nerve cells (neurons) in the brain die. These are neurons that produce a chemical called dopamine. Dopamine helps relay messages between areas of the brain that control body movement.
When these neurons die, abnormally low levels of dopamine are produced. This makes it difficult to control muscle tension and muscle movement.