Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease in which patients experience tremors, rigidity, and akinesia (the inability to move). After Alzheimer's, it is the second most common neurodegenerative disease (which involves progressive destruction of nerve cells).

Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra, a region of the basal ganglia in the brain (pictured below). As the name suggests, dopaminergic neurons produce dopamine, a critical neurotransmitter associated with motor control. This loss of dopamine leads to the hallmark symptoms of PD — tremors, muscular rigidity, and slow movement. Over time, the symptoms may worsen as patients begin to experience cognitive decline and develop emotional changes such as depression.

The exact cause of Parkinson's is not entirely clear, but a combination of genetics and the environment appears to be the culprit. The disease is linked to a mutation in the PARK2, or PRKN, a gene that codes for the protein parkin. PD patients also have high levels of Lewy bodies, accumulations of the alpha-synuclein protein.

While there is no cure for Parkinson's disease, there are treatments that can relieve its symptoms. Levodopa (also known as L-dopa) is a medication that increases dopamine levels in order to relieve motor symptoms. However, prolonged use of this medication can cause side effects. Another surgical procedure known as deep brain stimulation (DBS) is being used to treat PD patients who are not responding to medications. This technique used a small device that sends electrical impulses to interfere with brain signals. Researchers are also looking into stem cells as a way of replacing damaged dopaminergic neurons.

Read more about deep brain stimulation here.

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Image Credit:
(1) “Parkinson's Disease.” Wikimedia Commons, 28 Aug. 2013, upload.wikimedia.org/wikipedia/commons/c/cb/Blausen_0704_ParkinsonsDisease.png.

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