Trends in the Overlap of Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder: Prevalence, Clinical Management, Language and Genetics

Abstract

To review recent literature on the overlap of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), now both conditions can be dually diagnosed in the Diagnostic and Statistical Manual of Mental disorders 5th edition. There is a high comorbidity with rates of comorbid ASD and ADHD ranging from 40 to 83%. Multidisciplinary assessment and management of the combined presentation is thus required. Language difficulties are a common comorbidity in both ASD and ADHD with around 60% of children with ASD and 40% of those with ADHD having language problems. Twin studies show up to 72% of the co-variance of ADHD, and ASD symptoms can be explained by shared additive genetic factors providing a genetic basis for the observed clinical overlap. There are still many gaps in our knowledge with limited research exploring well-defined groups of children with ASD only, ADHD only and ASD with ADHD. Clinicians should thoroughly assess ADHD symptomatology in children with ASD and vice versa to understand the challenges for these children and inform treatment planning.