Early developmental milestones associated with tics and psychopathological comorbidity: An EMTICS study

Background: Chronic Tic disorders (CTD) including Tourette Syndrome (TS), are associated with psychopathological comorbidities. Attention deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and other comorbidities have been linked to delays in early developmental milestones. Few studies have investigated the relationship between early developmental milestones, tic severity, and related comorbidities. Methods: 383 participants aged 3–16 years (76.8%, n = 294 boys) with CTD from the baseline assessment of the European Multicenter Tics in Children Study (EMTICS), were evaluated for: retrospective early developmental milestones (sitting, walking, first words, complete a sentence, bladder and bowel control), tic severity, tic-related functional impairment, obsessive–compulsive disorder (OCD), ADHD, oppositional defiant disorder (ODD) and suspected ASD. Data was collected using gold-standard self and clinician reporting instruments. Analyses included Pearson correlations and logistic regressions. Results: Correlations between the acquisition of developmental milestones and tic severity or impairment were significant with small effect sizes (severity of motor tics and tic impairment were correlated with walking (r =.11), while vocal tics were correlated with first words (r =.12)). Logistic regression revealed that delayed acquisition of first words was significantly associated with ADHD, ODD and suspected ASD (Odds Ratio (ROR): 1–1.13, 1.04–1.22, 1.05–1.21, respectively), while delayed walking acquisition was associated with OCD (ROR: 1.01–1.27). Discussion: This study highlights the association between early developmental milestones and later psychopathological comorbidities in CTD patients. These findings emphasize the need for further research to distinguish between children with only tics and those with tics and psychopathological comorbidities, to improve early detection of individuals at risk.