Parkinson's Disease

Definition

Parkinson's disease (PD) is a motor system disorder caused by the chronic, progressive degeneration of neurons (nerve cells) in regions of the brain that control movement. PD causes a decline in the initiation, speed, and smoothness of movement. Over time it may come to affect many bodily functions.

Description

Parkinson's Disease (PD) was first described in 1817 by James Parkinson. It affects more than one million people in the United States, including some 500,000 people who have yet to be diagnosed. About 50,000 new cases are diagnosed each year. The average age of PD onset is 60. Symptoms of PD are seen in as many as 15% of those between the ages 65 and 74 and almost 30% of those between the ages of 75 and 84. Only 5 to 10% of PD cases occur before the age of 50. Young-onset PD occurs in those under age 40. A parent or sibling with PD increases one's risk of developing the disease.

PD results from the degeneration and death of neurons in the substantia nigra, movement control centers on each side of the brain. These cells secrete dopamine, a neurotransmitter that attaches to receptors on cell surfaces in another part of the brain—the corpus striatum—that controls muscle action. When dopamine levels fall, the neurons of the corpus striatum begin to misfire. It is estimated that dopamine-producing cells begin dying about 13 years before PD symptoms become evident. The symptoms of PD begin when about 60% of the dopamine-producing cells have died.

Causes

Although the cause of Parkinson's Disease (PD) is unknown, it appears to result from a combination of environmental and hereditary factors as well as oxidative damage and aging. Factors for PD may include:

• herbicide and pesticide exposure
• an as-yet-unidentified toxin or virus
• cellular damage from oxidation by free-radicals (atoms or molecules with an unpaired electron)
• loss of dopamine-secreting cells with age, particularly with accelerated aging
• fewer dopamine-secreting cells at birth

Content licensed from:

Author Info: Paula Ford-Martin, Margaret Alic PhD, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Alternative Medicine, 2005

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.