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Crowe M, Andel R, Wadley VG, Okonkwo OC, Sawyer P, Allman RM.Crowe M, et al.J Gerontol A Biol Sci Med Sci. 2008 Nov;63(11):1241-5. doi: 10.1093/gerona/63.11.1241.J Gerontol A Biol Sci Med Sci. 2008.PMID: 19038840Free PMC article.