Comorbidity burden and treatment patterns in Tourette syndrome and persistent motor or vocal tic disorder

This study compares Persistent Motor or Vocal Tic Disorder (PMVT) and Tourette Syndrome (TS) in a pediatric population, clarifying their relationship and exploring the validity of a continuous "Tic Spectrum Disorder" (TSD). We retrospectively analyzed data from 207 pediatric patients diagnosed with PMVT or TS. Analyses included group comparisons and multivariate ordinal logistic regression to identify factors independently associated with treatment burden. The cohort comprised 128 (61.8%) TS patients and 79 (38.2%) PMVT patients. The median age at tic onset was 7 years (interquartile range 6-9). Comorbidities were more frequent in TS than PMVT (p < 0.001). Specifically, ADHD, Obsessive-Compulsive Disorder, Specific Learning Disorders, Oppositional Defiant Disorder, Specific Phobias (all p < 0.001), and Intellectual Disability (p = 0.046) were all more prevalent in the TS group. TS patients required more therapeutic interventions compared to PMVT (p < 0.001). Notably, in multivariate analysis, the treatment burden was strongly associated with the cumulative comorbidity load, although a TS diagnosis also emerged as a significant independent factor. Within the TS group, patients with ADHD showed earlier tic onset (p = 0.021), higher comorbidity load (p < 0.001), and greater therapeutic needs (p < 0.001).

Our study identifies the cumulative burden of comorbidities as the primary factor strongly associated with treatment requirements, with the specific tic diagnosis also contributing independently to the therapeutic burden. While these findings support the conceptualization of a continuous TSD, they shift the clinical focus toward comorbidity load as a major factor linked to healthcare demand.

• Current classification distinguishes Tourette Syndrome (TS) and Persistent Motor or Vocal Tic Disorder (PMVT) based on tic types and duration, but this distinction often fails to predict therapeutic burden. • The existence of a continuous "Tic Spectrum Disorder" comprising both conditions is hypothesized but clinically debated.

• The cumulative comorbidity load is strongly associated with patients' treatment requirements, although a TS diagnosis also independently contributes to the overall therapeutic burden. • This study expands upon recent pediatric comparisons of TS and PMVT by incorporating a broader, previously under-investigated range of neurodevelopmental comorbidities.