ASD symptoms in adults with ADHD: a comparative study using ADOS-2.

In this study, we examined autism spectrum disorder (ASD) symptoms in adults with attention-deficit hyperactivity disorder (ADHD) in comparison with normal controls using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2). Sixty-three adults with ADHD (mean age, 35.3 years; 38 men) and 31 controls (mean age, 38.7 years; 17 men) completed Module 4 of the ADOS-2, Autism Spectrum Quotient, Conners' Adult ADHD Rating Scale, and Wechsler Adult Intelligence Scale, Third Edition. Adults with ADHD were not clinically diagnosed with ASD, and their ADHD diagnosis was based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria. Between-group comparisons on the scoring patterns revealed significant ASD symptoms present in adults with ADHD, which was congruent with our previous study. Further, item level and correlation analyses showed the possibility that ASD symptoms in adult ADHD comprised of two distinct mechanisms, one qualitatively similar to ASD and the other arising from ADHD characteristics, highlighting the complex nature of ADHD-ASD symptom overlaps.