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

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.

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.

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.

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.