Parkinson's disease (PD) is a neurodegenerative disorder that causes slowed movements, tremor, rigidity, and a wide variety of other symptoms. "Neurodegenerative" refers to the degeneration, or death, of neurons, the type of cell in the brain that is the basis for all brain activity.
Parkinson's disease occurs when neurons (nerve cells) in a part of the brain called the substantial nigra degenerate, or die off. The loss of these cells disrupts the brain's normal control of movement, causing the person to experience slowed movements, stiffness or rigidity, and tremor.

• Orthostatic hypotension, or loss of blood pressure upon standing, which can cause dizziness and fainting
• Painful foot cramps
• Micrographic, or reduced size of handwriting
• Reduced voice volume
• Reduced facial expression
• Excessive sweating
• Constipation
• Decreased ability to smell
• Male impotence
• Drooling
• Seep disturbance
• Depression
• Anxiety
• Panic attacks
• Late-stage dementia