Correlation of Comorbidities and Variability of Tics in Children with Chronic Tic Disorder.

Objective:  Chronic tic disorder (CTD) is characterized by the presence of motor and/or phonic tics, and is often accompanied by comorbidities, where obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are the most predominant. The aim of this study was to investigate a correlation between comorbidities and variability of tics in children with CTD.

Method:  A cross-sectional study was completed on a clinical cohort recruited from the Danish National Tourette Clinic at Herlev Hospital. The cohort consisted of 167 children who were examined by the Yale Global Tic Severity Scale. Data regarding comorbidity were collected on 152 of these patients by using validated diagnostic instruments, and the patients were divided into four subgroups: CTD-only, CTD + ADHD, CTD + OCD, and CTD + ADHD + OCD.

Results:  The comorbidity subgroups had significantly higher severity, impairment, and Total Tic Scores compared to the CTD-only group (p-value ≤ 0.001, 0.001, 0.003, respectively). The assessment of the association between variability of tics and comorbidities showed a significantly higher Simple Phonic Tic Score in the CTD + OCD group compared to the CTD-only group (p-value = 0.003).

Conclusion:  This study showed significantly higher Simple Phonic Tic Scores in the CTD + OCD group compared to the CTD-only group, which suggests that awareness of the variability of tics in patients with CTD and comorbidities is important.Total Tic Scores, severity of tics, and impairment were significantly higher in the comorbidity subgroups compared to the CTD-only group, which support findings from previous studies.