The Impact of Co-occurring ADHD on Core Symptoms and Treatment Among Youth with Autism Spectrum Disorder.

Individuals with autism spectrum disorder (ASD) constitute an extremely heterogeneous group with highly variable clinical and psychological features. In the nearly eight decades since Leo Kanner’s earliest descriptions of infantile autism (1943) and Hans Asperger’s original report (1944), there have been significant changes in the way autism is conceptualized, diagnosed, and treated. These changes are the product of the myriad empirical investigations that have informed understanding of autism, multiple revisions of the Diagnostic and Statistical Manual, and theory-driven approaches to ameliorating symptoms associated with the disorder. Despite this progress, the immense heterogeneity that characterizes the autism spectrum contributes to challenges in diagnostic and treatment efforts. One critical source of such heterogeneity is psychiatric comorbidity, as the presence of co-occurring symptoms and disorders can impact symptom presentation and complicate treatment efforts. The comorbidity of autism and attention-deficit/hyperactivity disorder (ADHD) is of particular interest, given its high prevalence, suspected impact on several domains of functioning, and its potential to pejoratively impact developmental outcomes. Increased knowledge about this comorbidity will contribute to our understanding of the observed heterogeneity within the autism spectrum. This understanding may drive identification of subgroups within autism that will allow us to tailor treatments to groups that may be best responders. Thus, it is critical to understand the history and current state of the evidence regarding the comorbidity of autism and ADHD. This three-manuscript dissertation series explores the ASD/ADHD comorbidity, the relationship between ADHD symptoms and core social and sensory symptoms in autism, and evaluates the impact of ADHD symptoms on treatment outcomes for a social competence intervention for youth with ASD.