About the Authors

Ivy N. Cheung

Affiliation Department of Neurology, Northwestern University, Chicago, Illinois, United States of America

Phyllis C. Zee

Affiliation Department of Neurology, Northwestern University, Chicago, Illinois, United States of America

Dov Shalman

Affiliation School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America

Roneil G. Malkani

Affiliation Department of Neurology, Northwestern University, Chicago, Illinois, United States of America

Joseph Kang

Affiliation Department of Preventive Medicine-Biostatistics, Northwestern University, Chicago, Illinois, United States of America

Kathryn J. Reid

k-reid@northwestern.edu

Affiliation Department of Neurology, Northwestern University, Chicago, Illinois, United States of America

Competing Interests

The authors have read the journal's policy and the authors of this manuscript have the following competing interests: Reid: Philips Consumer Lifestyle Research Grant 2011, Zee: Philips Consumer Lifestyle Research Grant 2011, consultant for Philips/Respironics and Philips Respironics Educational Research Gift. The following authors have declared that no competing interests exist: Ivy N. Cheung, Dov Shalman, Joseph Kang, Roneil G. Malkani. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: INC PCZ DS KJR. Performed the experiments: INC RGM KJR. Analyzed the data: INC JK KJR. Contributed reagents/materials/analysis tools: PCZ KJR. Wrote the paper: INC KJR PCZ RGM DS JK.