Accepted for Publication: December 4, 2013.
Published Online: January 27, 2014. doi:10.1001/jamaneurol.2013.6030.
Study concept and design: Richardson, Levey, German.
Acquisition of data: Richardson, von Stein, Hossain, Buckley, Gearing, Levey, German.
Analysis and interpretation of data: Richardson, Roy, Shalat, Levey, German.
Drafting of the manuscript: Richardson, Roy, Buckley, German.
Critical revision of the manuscript for important intellectual content: Richardson, Roy, Shalat, von Stein, Hossain, Gearing, Levey, German.
Statistical analysis: Richardson, Roy, Shalat.
Obtained funding: Richardson, Levey, German.
Administrative, technical, and material support: von Stein, Hossain, Buckley, Gearing, Levey.
Study supervision: Richardson.
Conflict of Interest Disclosures: None reported.
Funding/Support: This research was supported in part by National Institutes of Health grants P30ES005022, T32ES07148, R21NS072097, R01ES015991, P30AG012300, P50AG05681, and P50AG025688.
Role of the Sponsor: The National Institutes of Health had no role in the design and conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.