Parkinson's Disease - Introduction

Introduction

Parkinson's disease (PD) is a slowly progressive neurological disorder that affects movement, muscle control, and balance. Parkinson’s disease is part of a group of conditions called motor system disorders, which are associated with the loss of dopamine-producing brain cells. These dopamine-associated motor disorders are referred to as parkinsonisms.

Parkinson's Disease and Dopamine Loss

Parkinson's disease occurs from the following process in the brain:

• PD develops as cells are destroyed in certain parts of the brain stem, particularly the crescent-shaped cell mass known as the substantia nigra.

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• Nerve cells in the substantia nigra send out fibers to the corpus stratia, gray and white bands of tissue located in both sides of the brain.
• There the cells release dopamine, an essential neurotransmitter (a chemical messenger in the brain). Loss of dopamine in the corpus stratia is the primary defect in Parkinson's disease.

Dopamine deficiency is the hallmark feature in PD. Dopamine is one of three major neurotransmitters known as catecholamines, which help the body respond to stress and prepare it for the fight-or-flight response. Loss of dopamine negatively affects the nerves and muscles controlling movement and coordination, resulting in the major symptoms characteristic of Parkinson's disease. Dopamine also appears to be important for efficient information processing, and deficiencies may also be responsible for problems in memory and concentration that occur in many patients.

Click the icon to see an animation about Parkinson's disease.

Review Date: 06/18/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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