Ace Alzheimer Center Barcelona - Universitat Internacional de Catalunya, Barcelona, Spain. Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain. Apheresis Care Group and Fresenius Medical Care, San Francisco, California, USA. Nephrology Service, Hospital General Universitario Gregorio Marañón, Madrid, Spain. Departments of Neurology and Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. Alzheimer's Research Group, Grifols, Barcelona, Spain. Neurology Service, Hospital General Universitario Gregorio Marañón, Madrid, Spain. Memory Disorders Clinic, HM Hospitales, Madrid, Spain. American Red Cross Southern Blood Services Region, Atlanta, Georgia, USA. Medical Department, Banc de Sang i Teixits, Barcelona, Spain. Department of Pathology and Laboratory Medicine, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA.