Second Department of Neurology, "Attikon" University Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. Division of Neurology, McMaster University/ Population Health Research Institute, Hamilton, Canada. Department of Neurosciences and Mental Health, Hospital de Santa Maria, CHULN, University of Lisbon, Lisbon, Portugal. Department of Neurology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands. Department of Hygiene, Epidemiology and Medical Statistics School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA02115, USA. Second Department of Psychiatry, "Attikon" Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. Department of Neurology, University Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, Greece. Third Department of Pediatrics, National and Kapodistrian University of Athens, Athens, Greece. Third Department of Critical Care Medicine, Evgenideio Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece. Fourth Department of Internal Medicine, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece. Hellenic Centre for Disease Control and Prevention, Athens, Greece. Second Department of Neurology, "Attikon" University Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece tsivgoulisgiorg@yahoo.gr. Department of Neurology, University of Tennessee Health Science Center, Memphis, TN, USA.