OBJECTIVETo study the clinical features and risk factors of co-morbid tic disorder (TD) in children with attention deficit hyperactivity disorder (ADHD).

METHODSA total of 312 children with ADHD were involved in this study. Subtypes of co-morbid TD, incidences of TD in different subtypes of ADHD (ADHD-I, ADHD-HI and ADHD-C) were observed. Thirteen potential factors influencing the comorbidity rate of TD in ADHD were evaluated by univariate analysis and multiple logistic regression analysis.

RESULTSForty-two of 312 children with ADHD suffered from co-morbid TD (13.5%). Comorbidity rate of TD in children with ADHD-C (24.1%) was significantly higher than in those with ADHD-HI (10.9%) and ADHD-I (8.8%) (P<0.05). There were 21 cases (50.0%) of transient TD, 12 cases (28.6%) of chronic TD, and 9 cases (21.4%) of Tourette syndrome. The univariate analysis revealed 6 factors associated with comorbidity: addiction to mobile phone or computer games, poor eating habits, infection, improper family education, poor relationship between parents and poor relationship with schoolmates. Multiple logistic analysis revealed two independent risk factors for comorbidity: improper family education (OR=7.000, P<0.05) and infection (OR=2.564, P<0.05).

CONCLUSIONSThe incidence of co-morbid TD in children with ADHD is influenced by many factors, and early interventions should be performed based on the main risk factors.