Accepted for Publication: June 22, 2011.
Author Contributions: Study concept and design: Gao and Ascherio. Acquisition of data: Gao, Schwarzschild, and Ascherio. Analysis and interpretation of data: Gao, Simon, Schwarzschild, and Ascherio. Drafting of the manuscript: Gao. Critical revision of the manuscript for important intellectual content: Simon, Schwarzschild, and Ascherio. Statistical analysis: Gao, Simon, and Ascherio. Obtained funding: Ascherio. Administrative, technical, and material support: Schwarzschild. Study supervision: Ascherio.
Financial Disclosure: Dr Gao has been a consultant for Teva.
Funding/Support: This study was supported by grants R01 NS048517, R01 NS061858, P01 CA055075, P01 CA87969, and K24NS060991 from the National Institute of Neurological Disorders and Stroke, National Institutes of Health.
Previous Presentation: This paper was presented at the XIX World Congress on Parkinson's Disease and Related Disorders; December 12, 2011; Shanghai, China.