1. Department “G.F. Ingrassia”, Hygiene and Public Health; University of Catania; Catania Italy
2. National School of Public Health, Carlos III Institute of Health; Madrid Spain
3. National University of Distance Education; Madrid Spain
4. Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP); Madrid Spain
5. EULEN Socio-sanitary services; Madrid Spain
6. Institute of Economics, Geography and Demography, Centre for Human and Social Sciences; Spanish National Research Council; Madrid Spain
7. Consortium for Biomedical Research in Neurodegenerative Diseases (CIBERNED); Carlos III Institute of Health; Madrid Spain
8. Alzheimer Disease Research Unit, CIEN Foundation; Carlos III Institute of Health; Alzheimer Center Reina Sofia Foundation; Madrid Spain
9. Research Network on Health Services and Chronicity (REDISSEC); Madrid Spain