Author Contributions: Dr Scher had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Scher, Eiriksdottir, van Buchem, Gudnason, Launer.
Acquisition of data: Sigurdsson, Eiriksdottir, Gudnason.
Analysis and interpretation of data: Scher, Gudmundsson, Sigurdsson, Ghambaryan, Aspelund, van Buchem, Gudnason.
Drafting of the manuscript: Scher.
Critical revision of the manuscript for important intellectual content: Gudmundsson, Sigurdsson, Ghambaryan, Aspelund, van Buchem, Eiriksdottir, Gudnason, Launer.
Statistical analysis: Scher, Gudmundsson, Ghambaryan, Aspelund, Launer.
Obtained funding: Eiriksdottir, Gudnason.
Administrative, technical, or material support: Sigurdsson, Eiriksdottir, van Buchem, Gudnason.
Study supervision: Sigurdsson, van Buchem, Gudnason, Launer.
Financial Disclosures: Dr Scher has served on advisory boards for Endo Pharmaceuticals and OrthoMcNeil Neurologics. The other authors report no financial disclosures.
Funding/Support: This study was funded by National Institutes of Health contract N01-AG-12100, the National Institute on Aging Intramural Research Program, Hjartavernd (the Icelandic Heart Association), and the Althingi (the Icelandic Parliament). Components of the study were also supported by the National Eye Institute, the National Institute on Deafness and Other Communication Disorders, and the National Heart, Lung, and Blood Institute. Funding in support of this analysis was provided by the Migraine Research Foundation.
Role of the Sponsor: None of the funding bodies had any role in the study design or conduct; data collection, management, analysis, or interpretation; or preparation, review, or approval of the manuscript.