1. Department of Neurology, University Duisburg-Essen, Essen, Germany
2. Divisions of Preventive Medicine and Aging, Brigham and Women's Hospital, Harvard Medical School
3. Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
4. Department of Gastroenterology and Hepatology, University Duisburg-Essen, Essen, Germany
5. Department of Gastroenterology, Hepatology and General Medicine, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia