What is Parkinson's disease?

Parkinson's disease is a chronic, degenerative neurological disorder that affects one in 100 people over age 60. While the average age at onset is 60, disease onset starts by age 40 in an estimated five to 10 percent of patients, and people as young as 30 can also be affected.

There is no objective test, or biomarker, for Parkinson's, so the rate of misdiagnosis can be relatively high, especially when the diagnosis is made by a non-specialist. Estimates of the number of people living with the disease therefore vary, but recent research indicates that Parkinson's afflicts at least 100,000 people in Canada, one million in the United States and approximately six million worldwide.

Parkinson's disease was first characterized extensively by an English doctor, James Parkinson, in 1817. Today, we understand Parkinson's to be a disorder of the central nervous system that results from the loss of cells in various parts of the brain, including a region called the substantia nigra. The substantia nigra cells produce dopamine, a chemical messenger responsible for transmitting signals within the brain that allow for coordination of movement. Loss of dopamine causes neurons to fire without normal control, leaving patients less able to direct or control their movement. Parkinson's is one of several diseases categorized by clinicians as movement disorders.

What causes Parkinson's disease?

The exact cause of Parkinson's disease is unknown, although research points to a combination of genetic and environmental factors. If a continuum existed, with exclusively genetic causes at one end and exclusively environmental causes at the other, different patients would likely fall at many different places along that continuum.

For most Parkinson's patients, the cause lies somewhere in the middle. While many patients report one or more family members with the disease, it is not always clear that one or several genes are the cause. Similarly, while some patients suspect that exposure to one or another chemical or environmental toxin caused their Parkinson's Disease, this also cannot be conclusively proved. Scientists currently believe that, in the majority of cases, genetic and environmental factors interact to cause Parkinson's disease. Research into this subject continues aggressively every day. Unfortunately, however, it is generally impossible to determine what specifically caused an individual's Parkinson's Disease.

*source: www.michaeljfox.org