BACKGROUND: Epidemiological and clinical studies suggest that attention deficit hyperactivity disorder (ADHD) and reading disability co-occur more frequently than would be expected by chance. The purposes of this study were to (i) assess the frequency of Japanese syllabary (Kana) reading disability (RD) and (ii) measure the psychometric properties of the Das-Naglieri Cognitive Assessment System (DN-CAS) in a clinic-referred sample of Japanese children with ADHD. METHODS: Twenty children with ADHD aged 8-13 years were evaluated using both Kana reading tasks and the DN-CAS. RESULTS: Seven children (35%) showed excessive reading time in at least two of four Kana reading tasks and were diagnosed as ADHD plus RD. The children with ADHD plus RD took significantly longer to read a single mora, four-syllable words, and short sentences. There was no significant difference in the time it took the children with ADHD plus RD to read four-syllable non-words compared to the children with ADHD only. The children with ADHD plus RD had significantly lower simultaneous-processing scores in the DN-CAS compared to children with ADHD but not RD. CONCLUSION: Children with ADHD should be given Kana reading tasks because RD is highly comorbid with ADHD. DN-CAS is a useful method for evaluating cognitive processing in children with ADHD with or without RD.
BACKGROUND: Epidemiological and clinical studies suggest that attention deficit hyperactivity disorder (ADHD) and reading disability co-occur more frequently than would be expected by chance. The purposes of this study were to (i) assess the frequency of Japanese syllabary (Kana) reading disability (RD) and (ii) measure the psychometric properties of the Das-Naglieri Cognitive Assessment System (DN-CAS) in a clinic-referred sample of Japanese children with ADHD. METHODS: Twenty children with ADHD aged 8-13 years were evaluated using both Kana reading tasks and the DN-CAS. RESULTS: Seven children (35%) showed excessive reading time in at least two of four Kana reading tasks and were diagnosed as ADHD plus RD. The children with ADHD plus RD took significantly longer to read a single mora, four-syllable words, and short sentences. There was no significant difference in the time it took the children with ADHD plus RD to read four-syllable non-words compared to the children with ADHD only. The children with ADHD plus RD had significantly lower simultaneous-processing scores in the DN-CAS compared to children with ADHD but not RD. CONCLUSION:Children with ADHD should be given Kana reading tasks because RD is highly comorbid with ADHD. DN-CAS is a useful method for evaluating cognitive processing in children with ADHD with or without RD.