1. Department of Epidemiology and Biostatistics, College of Human Medicine Michigan State University East Lansing Michigan USA
2. The Memory Impairment and Neurodegenerative Dementia Center University of Mississippi Medical Center Jackson Mississippi USA
3. Department of Psychiatry and Behavioral Sciences Duke University Medical Center Durham North Carolina USA
4. Epidemiology Branch, National Institute of Environmental Health Sciences Research Triangle Park North Carolina USA
5. Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics National Cancer Institute Rockville Maryland USA