Declaration of competing interest The authors report no conflict of interest as related to research covered in this article. This research was not funded by any commercial or governmental agency. Luca Marsili has received honoraria from the International Association of Parkinsonism and Related Disorders (IAPRD) Society for social media and web support. Dr. Marsili has received a grant (collaborative research agreement) from the International Parkinson's and Movement Disorders Society for the MDS-UTRS Validation Program (Role: PI), Non-Profit. Carlo Colosimo received grants from Abbvie, Alfasigma, BIAL, Ipsen and Zambon unrelated to the present research, honoraria from the Movement Disorders Society, and publishing royalties Oxford University press and Cambridge University Press.