Medical illustration of dopamine in the brain
Falling levels of dopamine cause messages from the brain to some parts of the body to be interrupted

What is Parkinson's Disease?

Parkinson's disease is a degenerative neurologic disease. Degenerative means "declining in quality;" thus, the disease increases in severity over time; neurologic refers to the nervous system.

Therefore, Parkinson's disease is a disease of the nervous system that gets worse over time.

Parkinson's disease is also a chronic, progressive neurologic disease. Chronic means "of long duration" and progressive means "proceeding in steps" or "advancing." Parkinson's disease does not go away and it gradually gets worse.

Parkinson's disease is named after the English physician James Parkinson, who first described the illness. Another name for this illness is paralysis agitans, which is simply the Latin translation of "shaking palsy." The names Parkinson's disease, shaking palsy and paralysis agitans all refer to the same illness.

What Happens in Parkinson's Disease?

In Parkinson's disease, neurons (nerve cells) of the brain area known as the substantia nigra (Latin for "black substance") are primarily affected.

When neurons in the substantia nigra degenerate, the brain's ability to generate body movements is disrupted and this disruption produces signs and symptoms characteristic of Parkinson's disease:

  • Tremor

  • Rigidity

  • Akinesia (lack of movement or loss of spontaneous movement)

  • Bradykinesia (slowness of movement)

  • Problems with walking and posture.


Falling levels of dopamine cause messages from the brain to some parts of the body to be interrupted.

Any person who has the signs and symptoms characteristic of Parkinson's disease is said to have parkinsonism, but not every person with parkinsonism has Parkinson's disease, it's only one of the possibilities.

Patients and their families need to understand parkinsonism, because some 20 to 25 percent of people diagnosed with Parkinson's disease will eventually be discovered to have some other form of parkinsonism. Parkinsonism may look like Parkinson's disease, but over time it does not act like it.

For this reason, if you have been diagnosed with Parkinson's disease it is important to see a neurologist who has experience diagnosing and treating this disorder.

For more information about the University Physicians Consultation and Referral Service, please call 1-800-492-5538 (patients) or 1-800-373-4111 (physicians).

This page was last updated: May 24, 2013

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