[Autism and attention deficit hyperactivity disorder: convergences and divergences. Genetics]

According to the DSM-5, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are different conditions that earlier versions of the DSM stated could not be diagnosed together in the same individual. Yet, over the last few decades the debate on the limits between the two disorders has continued, even though ADHD and ASD are undoubtedly clinically and cognitively different phenotypes, as demonstrated by the simple fact that they have been defined in clearly different ways. Thus, from a perspective anchored in a purely phenomenological view, there would be no grounds whatsoever on which to question the independence between the two disorders. Since, at the present time, the discussion on the convergence between ADHD and ASD cannot be considered to have been solved, this study aims to take the data available from genetics as the basis on which to review the nosological position of the two disorders. The main studies that have addressed this issue are reviewed. The data collected agree on a genetic overlap between ADHD and ASD, which is influenced by common molecular mechanisms that affect the two disorders at the same time. The conclusions that can be drawn from the data collected suggest a new conceptual model not only for ADHD and ASD, but also for complex mental disorders in general. This line of research will transform the way of understanding the treatment of mental disorders and will almost certainly open up new perspectives in this area.