[1] CSIC, IEGD, Grp Invest Envejecimiento GIE, Madrid 28037, Spain
[2] Natl Distance Educ Univ UNED, Dept Geog, Madrid 28040, Spain
[3] CSIC, CCHS, Unidad Anal Estadist UAE, Madrid 28037, Spain
[4] Carlos III Inst Hlth, Natl Ctr Epidemiol & Hlth Serv Res Network Chron, Madrid 28029, Spain
[5] Natl Distance Educ Univ UNED, Fac Psychol, Dept Personal Evaluat & Psychol Treatment, Madrid 28040, Spain
[6] Carlos III Inst Hlth, Natl Ctr Epidemiol & Network Ctr Biomed Res Neuro, Madrid 28029, Spain