MSD Manual

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Parkinson Disease
Parkinson Disease
Parkinson Disease

The brain is composed of gray and white matter containing millions of nerve cells. These nerve cells, or neurons, communicate through the release of chemicals called neurotransmitters. Once a neuron is stimulated, a neurotransmitter is released from the neuron and it crosses a gap called a synapse; it then binds to a receptor on another neuron, thus passing on a signal.

Parkinson’s disease is a degeneration of the area of the brain responsible for muscle movements, specifically, the pigmented neurons located in the substantia nigra in the midbrain. The destruction of these neurons results in a decreased availability of dopamine, which is a type of neurotransmitter. As a result, nerves in this area cannot send their signal to other nerves in order to direct specific body movements. The result is body tremors, slowness of movement, rigidity and balance problems.

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Parkinson Disease (PD)