1. Epidemiology Unit, ASL TO3 Regione Piemonte, 10095 Grugliasco, Italy
2. Neurology Unit, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
3. Department of Health Sciences, and CAAD, University of Eastern Piedmont, 28100 Novara, Italy
4. Department of Biological and Clinical Sciences, University of Turin, 10128 Torino, Italy