Accepted for Publication: October 8, 2011.
Author Contributions: Study concept and design: Callaghan, Kerber, Xu, Langa, and Feldman. Analysis and interpretation of data: Callaghan, McCammon, Kerber, Langa, and Feldman. Drafting of the manuscript: Callaghan. Critical revision of the manuscript for important intellectual content: McCammon, Kerber, Xu, Langa, and Feldman. Statistical analysis: Callaghan, McCammon, and Kerber. Obtained funding: Langa and Feldman. Study supervision: Callaghan, Langa, and Feldman.
Financial Disclosure: Dr Kerber has received speaker honoraria from the AAN 2010 and 2011 annual meetings and has performed consulting work for the AAN.
Funding/Support: Drs Callaghan and Feldman were supported by a National Institutes of Health T32 grant, the Katherine Rayner Program, and the Taubman Medical Institute. The HRS was supported by grant U01 AG09740 from the National Institute on Aging and was performed at the Institute for Social Research, University of Michigan. Dr Langa was supported by grant R01 AG030155 from the National Institute on Aging. Dr Kerber was supported by grant K23 RR024009 from the National Center for Research Resources, National Institutes of Health, and grant R18 HS017690 from the Agency for Healthcare Research and Quality.
Previous Presentation: This study was presented at the 63rd American Academy of Neurology Annual Meeting; April 12, 2011; Honolulu, Hawaii.
Additional Contributions: James Burke, MD, reviewed and edited the manuscript.