Dorly J H Deeg1, Hans-Werner Wahl2, Howard Litwin3. 1. 1Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands. 2. 2Department of Psychological Aging Research, University of Heidelberg, Heidelberg, Germany. 3. 3Paul Baerwald School of Social Work and Social Welfare, Hebrew University, Jerusalem, Israel.