Course of Tourette Syndrome and Comorbidities in a Large Prospective Clinical Study

Objective: Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder characterized by tics and frequent comorbidities. Although tics often improve during adolescence, recent studies suggest that comorbid obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD) tend to persist. This large prospective follow-up study describes the clinical course of tics and comorbidities during adolescence and the prevalence of coexisting psychopathologies.

Method: The clinical cohort was recruited at the Danish National Tourette Clinic, and data were collected at baseline (n = 314, age range 5-19 years) and at follow-up 6 years later (n = 227) to establish the persistence and severity of tics and comorbidities. During follow-up, the Development and Well-Being Assessment (DAWBA) was used to diagnose coexisting psychopathologies. Repeated measures of severity scores were modeled using mixed effects models.

Results: Tic severity declined yearly (0.8 points, CI: 0.58-1.01, on the Yale Global Tic Severity Scale [YGTSS]) during adolescence; 17.7% of participants above age 16 years had no tics, whereas 59.5% had minimal or mild tics, and 22.8% had moderate or severe tics. Similarly, significant yearly declines in severity of both OCD (0.24, CI: 0.09-0.39, on the Yale-Brown Obsessive Compulsive Scale for Adults [Y-BOCS] and Yale-Brown Obsessive Compulsive Scale for Children [CY-BOCS]) and ADHD (0.42, CI: 0.32-0.52, DSM-IV) were recorded. At follow-up, 63.0% of participants had comorbidities or coexistent psychopathologies, whereas 37.0% had pure TS.

Conclusion: Severity of tics, OCD, and ADHD were significantly associated with age and declined during adolescence. However, considerable comorbidities and coexisting psychopathologies persist throughout adolescence and require monitoring by clinicians.