Objective: The purpose of this study was to investigate the clinical utility of the Korean Wechsler Intelligence Scale for Children-Fourth Edition (K-WISC-IV) and General Ability Index (GAI) in children with attention-deficit hyperactivity disorder (ADHD). Methods: The GAI and Full Scale IQ (FSIQ) in K-WISC-IV were compared for a group of 79 children with ADHD and 234 normal children. The mean differences within each group were testified by the t-test and Cohen's d. The Wechsler's descriptive

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... assifications for each GAI and FSIQ score were analyzed in the children with ADHD. Additionally, the critical value for the difference between the means of the FSIQ and GAI was calculated in the normal children. Results: The score on the GAI was higher than that on the FSIQ in the children with ADHD, with a mean difference of 2.19 points. The implications of these findings are discussed regarding the cognitive characteristics of the children with ADHD. According to Wechsler's descriptive classification, the application of the GAI showed a lower (7.59%), equal (61.65%) or higher (60.76%) prevalence of ADHD compared to the application of FSIQ. Conclusion: The implications of these findings are discussed regarding the cognitive characteristics of the children with ADHD. The GAI reflecting the attention and behavioral problems in children with ADHD could be utilized as an alternative global intelligence estimate that considers their potential for development.