Predictors of the Clinical Course of Tourette Syndrome: A Longitudinal Study

Objective: Tourette syndrome (TS) is a chronic childhood neurodevelopmental disorder characterized by motor and vocal tics and frequent comorbidities. The clinical presentation of Tourette syndrome is heterogeneous and the prognosis for each individual child is difficult to define. This large prospective longitudinal study explores predictors in childhood of the clinical course of tics and comorbidities in early adulthood. Methods: The cohort was recruited at the Danish National Tourette Clinic. Data were collected at baseline (N = 314; ages, 5-19 years) and follow-up 6 years later (n = 227; ages, 11-26 years) to examine changes in the expression of tics and comorbidities. Childhood clinical factors, represented by 4 binary clinical outcomes, were selected as possible predictors of the clinical course of tics and comorbidities in early adulthood; these were tic severity and diagnoses of obsessive compulsive disorder (OCD), attention-deficit hyperactivity disorder (ADHD), and emotional disorders. Results: The strongest predictors of high tic scores, OCD, or ADHD diagnoses in early adulthood were the corresponding tic (odds ratio [OR]: 1.09), OCD (OR: 1.08), and ADHD (OR: 1.13) severity scores (per scale point) in childhood. Being female (OR: 3.94) and childhood ADHD severity (OR: 1.11) predicted future emotional disorders. Special education, genetic factors, and psychosocial factors were also predictive for the clinical course of Tourette syndrome. Conclusion: We identified strong clinical predictors of Tourette syndrome-associated outcomes in early adulthood that are directly applicable to clinical Tourette syndrome populations and may help to guide new patients, plan early interventions, and implement preventive measures.