[1] Wake Forest Univ, Sticht Ctr Aging, Winston Salem, NC 27157 USA
[2] Univ Sacred Heart, Dept Geriatr, I-00168 Rome, Italy
[3] Univ Pittsburgh, Dept Med, Pittsburgh, PA USA
[4] Univ Tennessee, Dept Prevent Med, Memphis, TN USA
[5] Univ Pittsburgh, Dept Epidemiol, Pittsburgh, PA 15260 USA
[6] Univ Vermont, Dept Biochem, Burlington, VT 05405 USA
[7] Univ Calif San Francisco, Dept Med, San Francisco, CA 94143 USA
[8] NIA, Lab Epidemiol Demog & Biometry, Bethesda, MD 20892 USA