1. Harvard Center for Population and Development Studies Harvard University Cambridge Massachusetts USA
2. Center for Economic and Social Research University of Southern California Los Angeles California USA
3. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) School of Public Health Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa
4. Taub Institute for Research on Alzheimer's Disease and the Aging Brain Vagelos College of Physicians and Surgeons Columbia University New York New York USA
5. Gertrude H. Sergievsky Center Vagelos College of Physicians and Surgeons Columbia University New York New York USA
6. Department of Neurology Vagelos College of Physicians and Surgeons Columbia University New York New York USA
7. Department of Epidemiology and Biostatistics University of California San Francisco California USA
8. Institute for Healthcare Policy and Innovation University of Michigan Ann Arbor Michigan USA
9. Department of Internal Medicine University of Michigan Medical School Ann Arbor Michigan USA
10. Institute for Social Research University of Michigan Ann Arbor Michigan USA
11. Veterans Affairs Center for Clinical Management Research Ann Arbor Michigan USA
12. Division of Geriatric Medicine School of Clinical Medicine Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa
13. Department of Social and Behavioral Sciences Harvard T.H. Chan School of Public Health Boston Massachusetts USA