Comparing Intelligence Test Profiles to Assess Tourette’s Disorder with Attention-Deficit Hyperactivity Disorder

Objectives: The study compared the intelligence test profiles of Tourette’s Disorder (TD), attention-deficit hyperactivity disorder (ADHD), and TD with ADHD (TD+ADHD) groups. Methods: The Korean Wechsler Intelligence Scale for Children-third edition (K-WISC-III) and Korean Wechsler Intelligence Scale for Children-fourth edition (K-WISC-IV) were administered to 13 children and adolescents with TD, 17 children and adolescents with ADHD, and 15 children and adolescents with TD+ADHD. Each parameter was compared among the groups using the Kruskal-Wallis test. Results: The mean scores of the freedom from distractibility/working memory index (FD/WMI) and the digit span and arithmetic subtests of the TD+ADHD group were significantly lower than those of the TD group. Conclusion: According to the intelligence test results, the comorbid ADHD+TD group showed a significant decrease in working memory compared to the TD group. These findings are similar to those of previous research on cognitive functions and suggest that the TD+ADHD comorbid and TD alone groups exhibit different endophenotypes. The results also imply that WISC-III and WISC-IV, the most commonly used intelligence tests clinically, are effective in evaluating cognitive functions such as attention. Further research is required to confirm these results.