Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Parkinson's Disease

Parkinson's disease is a neurodegenerative disease that is caused by the loss of neurons [ For more on 'neurons' go here: http://www.braingle.com/mind/317.html ] in the part of the brain that produces dopamine. Dopamine is a chemical that helps coordinate muscle movement and memory formation. In addition to the muscle tremors that most people associate with Parkinson's disease, visual memory is often affected as well. Depression, dementia and general memory loss can also occur in patients with the disease.

The cause of Parkinson's disease is not entirely understood, but the prevalent theory is that genetic factors combined with certain toxins can be a trigger. Studies have found that people exposed to pesticides and other agricultural chemicals have a higher risk of developing the disease. Head trauma can also play a small roll.
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For more mind exercises: http://www.braingle.com/mind/