Heterogeneity in Tics and Gilles de la Tourette Syndrome

Abstract Gilles de la Tourette syndrome (GTS) is no longer considered a unitary condition, with converging evidence emerging on potential subphenotypes. This chapter explores the heterogeneity of GTS, beginning with a thorough review of factor, cluster, and latent class analysis studies. Despite methodological differences, several findings are replicated across these studies. These include the presence of a “pure tics” factor, clustering of tic symptoms by complexity and type, and the existence of groups of related comorbid symptoms such as impulse control difficulties and obsessive-compulsive behaviors. This chapter then reviews epidemiological studies with a focus on clinical features, comorbidities, and associated psychopathologies, as well as genetic underpinnings. An improved understanding of the heterogeneity of GTS and its potential subphenotypes is critical to explaining differential treatment response and improving overall outcomes.