Links Between Autism Spectrum Disorder and ADHD Symptom Trajectories: Important Findings and Unanswered Questions

Abstract

A n exclusion item within the DSM-IV-TR attention-deficit/hyperactivity disorder (ADHD) diagnostic criteria discourages the diagnosis of ADHD if symptoms occur only during the course of a pervasive developmental disorder. However, according to the latest proposed revisions, this may change for DSM-5. Proposed changes for DSM-5 also include a change in the classification of pervasive developmental disorders, which would eliminate separate diagnoses of autistic disorder, Asperger’s disorder, and pervasive developmental disorder not otherwise specified, placing these instead into the single category of autism spectrum disorders (ASDs). The article by St. Pourcain et al in this month’s issue of the Journal adds support to arguments for allowing the co-diagnosis of ADHD and ASD and has some immediate implications for clinical practice and research strategies for neurodevelopmental disorders. Although multiple cross-sectional studies have demonstrated that ASD and ADHD symptoms frequently co-occur and have some overlapping genetic etiologies, little is known about the longitudinal relation between ASD and ADHD symptoms. Using a sample of more than 5,000 subjects from the Avon Longitudinal Study of Parents and Children (ALSPAC), St. Pourcain and colleagues examined the relation between longitudinal ADHD and ASD symptom trajectories through the use of latent class growth analysis. As their ASD symptoms measurement, these investigators used the 12-item Social Communication Disorders Checklist, which covers social reciprocity and communication but not repetitive/stereotyped behaviors. The ADHD symptoms measurement consisted of five items (two inattentive, two hyperactive-impulsive, one im-