Faculty of Social Sciences (Health Sciences) and Gerontology Research Center (GEREC), Tampere University, Tampere, Finland. Department of Public Health and Welfare, Population Health Unit, Finnish Institute for Health and Welfare, Helsinki, Finland. Department of Neurobiology, Care Sciences and Society, Division of Clinical Geriatrics, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden. Institute of Clinical Medicine/Neurology, University of Eastern Finland, Kuopio, Finland. Southern Ostrobothnia Central Hospital, Seinäjoki, Finland. Härmä Rehabilitation Center, Ylihärmä, Finland. South Ostrobothnia Memory Association, Ylihärmä, Finland. City of Seinäjoki, Finland. Department of Psychology, University of Cambridge, Cambridge, UK. Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland. Joint Municipal Authority for North Karelia Social and Health Services (Siun Sote), Joensuu, Finland. Neuroepidemiology and Ageing Research Unit, School of Public Health, Imperial College London, London, UK. Theme Aging, Karolinska University Hospital, Stockholm, Sweden. Stockholms Sjukhem, Research & Development Unit, Stockholm, Sweden.