Relationship Between Tourette Syndrome and Neurodevelopmental Disorders in Taiwan: A Population-Based Cohort Study

Background: Tourette syndrome (TS) frequently co-occurs with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and obsessive-compulsive disorder (OCD). Notably, few large-scale studies have quantified the longitudinal risks of these disorders by using hazard ratios (HRs). To address this gap, we used a nationwide cohort to estimate the HRs of ASD, ADHD, and OCD in patients with TS, with subgroup analyses by age and sex. Methods: Using data derived from a nationwide population-based database, this retrospective cohort study investigated the risk of ASD, ADHD, and OCD in patients with TS. A total of 7,986 patients with newly diagnosed TS between 2002 and 2016 were included, with each patient matched to four controls on the basis of age, sex, insured salary, urbanization level, Charlson Comorbidity Index score, and year of cohort entry. Participants were followed from the index date until the first occurrence of neurodevelopmental disorders, death, or the end of 2018. Results: After adjustment for potential confounding variables, patients with TS had significantly higher risks of ASD (adjusted HR aHR = 2.2, 95% confidence interval CI = 1.68–2.87), ADHD (aHR = 3.23, 95% CI = 2.93–3.57), and OCD (aHR = 5.18, 95% CI = 3.86–6.95). Additionally, patients aged younger than 7 years had higher risks of ASD and ADHD than did those aged 7–18 years (aHR = 0.31, 95% CI = 0.24–0.40) or >18 years (aHR = 0.12, 95% CI = 0.05–0.28). Male patients were also at a greater risk of developing ASD (aHR = 2.21, 95% CI = 1.49–3.28) and ADHD (aHR = 2.25, 95% CI = 1.92–2.63) relative to female patients. Conclusion: TS is a significant risk factor for ASD, ADHD, and OCD. Our findings indicate that individuals with TS are at an increased risk of developing these conditions. This study highlights the association between TS and other neurodevelopmental disorders. Further research is necessary to explore underlying causes and conduct more detailed analyses.