Score of inattention subscale of ADHD rating scale-IV is significantly higher for AD/HD than PDD.

Attention-deficit/hyperactivity disorder (AD/HD) and pervasive developmental disorder (PDD) must be differentiated because the respective treatments are different. However, they are difficult to distinguish because they often show similar symptoms. At our hospital, we have the rearer of a patient answer both the ADHD Rating Scale-IV (ADHD-RS) and the Autism Spectrum Screening Questionnaire (ASSQ), and use the results as an aid for the diagnosis of AD/HD or PDD.