Home > Encyclopedia of Neurological Disorders > Parkinson's Disease

Definition

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.

Description

Parkinson's disease occurs when neurons (nerve cells) in a part of the brain called the substantia 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.

Demographics

PD is one of the most common neurodegenerative diseases, second only to Alzheimer's disease in the number of people affected. Estimates suggest that approximately 750,000 Americans have PD. It affects older people much more...