Comparison of the K-WPPSI-IV Profiles Between Children With Attention-Deficit/Hyperactivity Disorder and Children With Autism Spectrum Disorder: A Retrospective Study

Objective This study aimed to: 1) compare the cognitive profiles of children with autism spectrum disorder (ASD), attention-deficit/ hyperactivity disorder (ADHD), and comorbid ADHD+ASD with typically developing (TD) children; and 2) examine the associations between indices of the Korean Wechsler Preschool and Primary Scale of Intelligence–Fourth Edition (K-WPPSI-IV) and other clinical assessments.Methods A retrospective chart review was conducted for 233 children aged 4–6 years who visited Asan Medical Center between April 2017 and September 2024. The study population included 74 children with ADHD+ASD, 46 with ASD, 84 with ADHD, and 29 TD children. The full-scale intellectual quotient, 5 indices, and 12 subtest scores of the K-WPPSI-IV were compared using analysis of covariance, adjusting for age. Correlations were analyzed between the K-WPPSI-IV indices and the symptom severity measures: Childhood Autism Rating Scale (CARS), ADHD Rating Scale (ARS), and Advanced Test of Attention (ATA) across the full population.Results Children with ADHD+ASD, ASD, and ADHD scored significantly lower than TD peers on the Working Memory Index (WMI; p<0.001) and Processing Speed Index (PSI; p<0.001). The ASD group showed significantly lower scores than the ADHD group in Vocabulary (p=0.001) and Comprehension (p<0.001). CARS scores negatively correlated with the WMI, while ATA negatively correlated with the PSI.Conclusion Both ADHD and ASD are associated with relative weakness in processing speed and working memory. Furthermore, ASD is characterized by additional difficulties in verbal abilities. These findings highlight distinct and overlapping cognitive features across these disorders.