Abstract
The symptoms of autism-spectrum disorder （ASD） and attention-deficit hyperactivity disorder （ADHD） were previously considered to be different, which did not permit the diagnosis of patients with comorbidities of ASD and ADHD using DSM-Ⅳ-TR. However, in some cases, the possibility of ASD and ADHD co-occurring was mentioned. Since 2013, the overlap between ASD and ADHD has been diagnosed using DSM-5. Individuals with ADHD frequently exhibit ASD characteristics and vice versa. This study aimed to compare the differences in clinical symptoms between ADHD and ASD using a self-rating questionnaire. This research was approved by the Institutional Review Board of Showa University under the strict management of handling personally identifiable information. The outpatients were recruited from Showa University and grouped into ASD, ADHD, and typical adults （TAs）. Patients with ADHD had a significantly higher autism-spectrum quotient score than the TAs. Furthermore, the Conner’s adult ADHD rating scale （CAARS） score was significantly higher in patients with ASD than in the TAs. In ASD, all CAARS subscale scores （inattention, hyperactivity, and impulsivity） were significantly higher than those in the TAs. In several instances, the features of ASD and ADHD overlapped. These overlapping symptoms may make it difficult for psychiatrists to diagnose ASD, ADHD, or both. Further investigations are required in this field to develop medications and psychotherapy for individuals with developmental disorders.
