Is Persistent Motor or Vocal Tic Disorder a Milder Form of Tourette Syndrome? - Claudio-Campos K; Stevens D; Koo SW; Valko A; Bienvenu OJ; Budman CB; Cath DC; Darrow S; Geller D; Goes FS; Grados MA; Greenberg BD; et al. (Movement disorders : official journal of the Movement Disorder Society, 2021)