Parkinson's Disease - Causes
The immediate cause of Parkinson's disease is the destruction of brain cells in a part of the brain known as the substantia nigra (SN). The substantia nigra controls many types of muscular movement by releasing a neurotransmitter called dopamine. A neurotransmitter is a chemical that transports electrical signals between brain cells. Dopamine is needed to carry nerve messages from one brain cell to another.
- Chronic:
- Recurring frequently or lasting a long time.
- Dopamine:
- A neurotransmitter that helps send signals that control movement.
- Neurotransmitter:
- A chemical that helps transmit electrical signals from one brain cell to another.
- Substantia nigra:
- A region of the brain that controls movement.
When brain cells die in the substantia nigra it doesn't release enough dopamine. Without dopamine, signals cannot travel from SN brain cells to cells in other parts of the brain. The "instructions" that brain cells need to move muscles do not reach their targets. Eventually, walking, writing, reaching for objects, and other basic movements do not occur correctly. Muscular movement becomes weaker and more erratic.
Researchers have not yet discovered the basic cause of Parkinson's disease. They do not know why SN brain cells lose the ability to produce dopamine. Some scientists think that the disease is hereditary. They believe that PD can be passed down from generation to generation. Other researchers think that environmental factors may be to blame. They suspect that certain chemicals in the world around us get into the human body and damage SN brain cells.
So far, a few chemicals have been found that cause the symptoms of PD. One chemical known to cause symptoms of PD is called MPTP. MPTP is sometimes found as an impurity in illegal drugs. A person who accidentally ingests (eats) MPTP begins to show signs of PD within hours. These symptoms become permanent.
"Shaking palsy" was a disease well known to physicians for hundreds of years. Patients with the disorder gradually became worse over a period of years. They slowly lost control over their limbs, and eventually lost the ability to dress and care for themselves.
The first scientific description of this disease was written in 1817 by Dr. James Parkinson (1755–1824). Parkinson was a man of many interests. Not only did he describe the nature of "shaking palsy," but he also provided the first explanation of appendicitis. Parkinson was also interested in the study of geology and paleontology (fossils), and was a social reformer. He fought for reform of the English parliamentary system and for better treatment of mental patients.
Parkinson also went one step beyond describing "shaking palsy." He conducted an autopsy on a patient who died of the condition. He found a swelling of the medulla, a part of the brain, which he said might be the cause of the disorder. For his research on this disease, "shaky palsy" was eventually renamed Parkinson's disease in his honor.
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