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In page Management of Parkinson's disease:

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Levodopa was first synthesized in 1911 by Casimir Funk, but it received little attention until the mid-20th century.[3] It entered clinical practice in 1967, and the first large study reporting improvements in people with Parkinson's disease resulting from treatment with levodopa was published in 1968. Levodopa brought about a revolution in the management of PD.[3][4] By the late 1980s deep brain stimulation emerged as a possible treatment, and it was approved for clinical use by the FDA in 1997.[5]