Parkinson’s Disease

What is Parkinson’s Disease?

Parkinson’s disease (PD) is a type of movement disorder that can affect the ability to perform common, daily activities. It is a chronic and progressive disease, meaning that the symptoms become worse over time. It is characterized by its most common of motor symptoms—tremors (a form of rhythmic shaking), stiffness or rigidity of the muscles, and slowness of movement (called bradykinesia)—but also manifests in non-motor symptoms including sleep problems, constipation, anxiety, depression, and fatigue, among others.

Who does the disease affect?

There are an estimated 1 million people in the U.S. living with Parkinson’s disease and more than 10 million people worldwide. Most people who develop the symptoms of Parkinson’s disease do so sometime after the age of 50, but Parkinson’s disease can affect younger persons as well. Approximately 10% of Parkinson’s diagnoses occur before age 50—these diagnoses are called Early Onset (or Young Onset) Parkinson’s disease.

How does Parkinson’s disease affect the brain?

Explaining the Science Behind Parkinson’s Disease

What makes Parkinson’s disease distinctive from other movement disorders is that cell loss occurs in a very specific region of the brain called the substantia nigra (sub-STAN-she-uh NYE-gruh). The nerve cells, or neurons, in this region actually appear dark under a microscope (substantia nigra is Latin for “black substance”).

Those dark neurons produce a specific type of neurotransmitter (a chemical messenger that allows neurons to communicate) called dopamine. The neurotransmitter dopamine helps to regulate movement. This loss of dopamine is the reason that many treatments for Parkinson’s Disease are intended to increase dopamine levels in the brain.

In addition to decreases in dopamine and the cells that make dopamine, you might also read or hear about alpha-synuclein (AL-fa-sin-NUKE-lee-un). We do not yet know what this protein does in the healthy brain, but in Parkinson’s disease it clumps up in what are called Lewy (LOO-ee) bodies. Researchers believe that alpha-synuclein build-up contributes to the cause of Parkinson’s disease and that it may be possible to develop new treatments based on this idea. Future research will hopefully tell us more about alpha-synuclein. Learn more about APDA research initiatives here.

Learn more about Parkinson’s disease

Parkinson’s Disease: The Essentials

If you’re new to Parkinson’s disease and would like a good overview to help you better understand the disease, please view our Parkinson’s Disease: The Essentials presentation. It’s a great place to get started with reliable and concise information.

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The exact cause of Parkinson’s is still unknown, but there is an enormous amount of research being done to learn more. This research has led scientists to formulate a number of theories on the cause of this disease.


While there is no definitive test that can be taken to determine whether a person has Parkinson’s disease, movement disorder specialists look for symptoms and use brain imaging technology to accurately diagnose Parkinson’s.


Even though Parkinson’s is classified as a movement disorder—and its motor symptoms are the most discussed and well-known—there are many non-motor symptoms that display in people with Parkinson’s as well.


As of today, there is no cure for Parkinson’s disease. But there are many ways in which the disease can be treated to make symptoms more manageable.

Living With Parkinson’s

It’s possible to maintain an active and positive lifestyle through healthy choices, medical assistance, and support from your family, friends, and community.

Stay up-to-date on the latest Parkinson’s information

A Closer Look with Dr. Rebecca Gilbert

A Closer Look is our ongoing series of articles written by Dr. Rebecca Gilbert, APDA Vice President and Chief Mission Officer. Dr. Gilbert discusses both timely and timeless Parkinson’s topics, and provides readers with insights that are applicable to their daily lives.