Vol. 8, Issue 1, Part A (2026)

Co-occurring Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) is currently the most common and difficult-to-manage dual diagnosis in child neuropsychiatric disorders. For many decades, these two conditions remained in separate diagnostic compartments according to conventional psychiatric nomenclature. With their unified recognition in DSM-5 in 2013, this recognition has completely transformed clinical approaches and research paradigms in this area. This narrative review is intended to be an exhaustive and systematic synthesis of the current scientific reality of ASD and ADHD in children. Its scope would include the regression of the available epidemiological studies in the field, analyzing their common and differing pathoetiological architectures in genetics, neuroscience, and neuromechanisms, while characterizing their own distinct phenotypes combined in this particular dual diagnosis setting. Since this dual diagnosis has explosive effects in terms of intellectual and adaptive performance in children, most of our discussion would address this aspect in depth. The vast implications in terms of academic, social, and adaptive functionalities, as well as outcomes, have been examined in depth. Finally, we have been able to identify areas of ongoing controversy, knowledge gaps, and future research areas including the need for trans-diagnostic approaches, studies of treatment sequencing, and approaches from a lifespan perspective. This review of existing literature brings closure to the immense body of knowledge available for the benefit of the reader to comprehend that the understanding of children with ASD and ADHD is more than just managing comorbidities.