Autism is a neurodevelopmental disorder that is behaviorally defined by the presence of a triad of behavioral impairments affecting social abilities, communication skills, and rigid, repetitive behaviors and interests. The DSM-IV-TR divides autism, or in its terminology, Pervasive Developmental Disorders, into diagnostic subcategories, including Asperger's Disorder, Autistic Disorder, and Pervasive Developmental Disorder–Not Otherwise Specified (PDD-NOS; a category for individuals who do not meet full criteria for autism). The application of these subcategories is inconsistent across clinics in the United States, however, and there is confusion about associated features and additional diagnoses, such as ADHD. The proposed criteria for a new category, Autism Spectrum Disorder (ASD), in the DSM-5 include dropping all subcategories of diagnosis and utilizing a dimensional approach to complement the single categorical label of ASD. This dimensional approach would allow for the designation of associated features as qualifiers, such as intellectual or language difficulties and ADHD. The term “ASD” is used throughout this chapter to describe research findings for Asperger's Disorder, Autistic Disorder, and PDD-NOS.

Executive dysfunction in ASD

Damasio and Maurer first linked ASD to EdF when they described behavioral similarities between individuals with ASD and those with frontal lesions, including lack of social motivation, poor communication, and perseverative behavior. Although EdF has not been demonstrated as a causal factor in ASD, it has been related to symptoms that define ASD, as well as to lower adaptive functioning in ASD. Findings of EdF are robust in school age children with ASD, who show specific impairment with tasks that require cognitive flexibility and organization. Reviews also highlight numerous studies where children with ASD demonstrate an impaired ability to plan on tasks such as the Tower of London.