[1] Univ Aberdeen, Sch Med & Dent, Epidemiol Grp, Aberdeen, Scotland
[2] UCL, MRC, Unit Lifelong Hlth & Ageing, London, England
[3] NIA, Lab Epidemiol & Populat Sci, NIH, Bethesda, MD 20892 USA
[4] Univ Cambridge, Inst Metab Sci, Sch Clin Med, MRC,Epidemiol Unit, Cambridge, England