Case Study : Isaac is a fifty-nine-year-old man. Several months ago, he noticed a slight tremor in his hands. He assumed this to be a normal consequence of aging. The tremor, however, gradually worsened, along with some muscular stiffness and slowness in initiating movement. The tremor was more pronounced when he was not voluntarily moving. Isaac was referred to a neurologist, who diagnosed him with Parkinson’s disease. After visiting the neurologist, Isaac and his family ask you to further explain this disorder. Isaac also asks about L-dopa as a treatment—the neurologist had mentioned L-dopa as an effective medication but had instead prescribed selegiline:

• What are the symptoms of Parkinson’s disease?
• What are the possible causes? Be sure to discuss both hereditary and environmental factors thought to contribute to this disease.
• What parts of the brain does this disease affect?
• Why do you think the neurologist prescribed selegiline instead of L-dopa?