The Facts
Parkinson's disease is a disease of the nervous system that causes people
to lose control over their muscles. About one in every 250 people over the
age of 40, and about one in every 100 people aged 65 or older, are affected
by Parkinson's disease. Although the average age of onset is 57, Parkinson's
occasionally appears in childhood. Men are more likely to develop Parkinson's
than women.
In itself, Parkinson's is not a fatal condition. However, the end-stage of
the disease can lead to pneumonia, choking, severe depression, and death.
Causes
Although the brain cells that control movement (the motor neurons)
are located along the top of the brain, they rely on a chemical called dopamine
that's manufactured in the stem of the brain (the basal ganglia).
In Parkinson's, dopamine-producing cells in the brainstem are lost. In most
cases, we don't know why. Primary Parkinson's disease is the diagnosis
in the majority of cases where the doctor doesn't know why these cells are dying.
Secondary Parkinsonism is due to some disease or chemical interfering
with or damaging dopamine-producing cells in the brainstem. The most common
cause is side effects of medication for other problems. Medications that can
cause secondary Parkinsonism include:
- haloperidol* and other medications used to treat hallucinations and confusion
in the elderly
- metoclopramide, a commonly prescribed anti-nausea drug
Less common causes of secondary Parkinsonism include poisoning by carbon monoxide
or manganese (a type of mineral), lesions and tumors in the brainstem, and a
rare illicit drug called N-MPTP. An outbreak in the years 1918 to 1924 of a
disease called von Economo's encephalitis left thousands of people across
North America with Parkinson's.
A number of genetic mutations have recently been identified suggesting that
Parkinson's may run in some families. However, a major U.S. twin study suggested
that environment plays a larger role than inheritance. The current consensus
is that genetic factors are dominant only in Parkinson's that appears before
age 50.
