Commentary: Developmental origins of autism and ADHD - A commentary on Johnson et al. (2015)

Abstract

Autism (autistic spectrum disorder, ASD) and attention deficit hyperactivity disorder (ADHD) are two highly prevalent neurodevelopmental disorders. Current estimates for autism exceed 1% For ADHD, the 2013 US-based life time prevalence figure is 11%. Both disorders are also highly heritable. Intriguingly, approximately 50% of children with ASD also meet criteria for ADHD. Between their high heritability and comorbidity, some have wondered whether these two seemingly different disorders might in fact be related at some deep neurobiological level. The notion that these two disorders may be related is surprising when one considers the fact that autism generally appears in the first 1-2 years of life, whereas it is virtually impossible to identify ADHD during this time frame; indeed, inattentiveness and hyperactivity tend to be traits that are shared by nearly all toddlers, making a stable diagnosis of ADHD virtually impossible until early childhood (although a reliable diagnosis can generally be made during the preschool period). Like many neurodevelopmental disorders, early identification and early treatment are essential to easing the life time burden of these disorders. Of course, early treatment is predicated on early identification and it is for this reason that the review article by Johnson and colleagues is so intriguing, as it sets out to determine whether these disorders can be identified in the infancy period. It also raises a number of puzzling issues that remain undiscussed.