Funding for this research was provided by:
U.S. Department of Veterans Affairs
National Institute on Aging (R56 AG047402-01A1)
Received: 8 February 2018
Accepted: 5 November 2018
First Online: 29 November 2018
Ethics approval and consent to participate
: The present study was conducted as part of protocol Pro00006711, which was approved by the Duke University Health System Institutional Review Board for Clinical Investigations, with a waiver of signed informed consent of participants in accordance with 45CFR46.117(c)  and an alteration of HIPAA authorization in accordance with 45CFR164.512(i) [CitationRef removed].
: Not applicable.
: The authors declare that they have no competing interests.
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