Idiopathic Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication as well as restricted and repetitive patterns of behavior, interests, or activities. Social deficits tend to appear within the first 2 years of life, including, failure to respond to name and delayed or absent language acquisition. In early childhood, difficulties with social pragmatics, such as eye contact, reciprocal conversation, turn-taking, greetings, figurative language, and understanding nonverbal cues become more apparent. Restrictive and repetitive behaviors can range from “lowerorder” behaviors—repetitive motor actions and movements—to “higher order” behaviors, which are characterized by routines, insistence on sameness, and narrowed interests. Psychiatric comorbidities and neuropsychiatric symptoms are common in ASD, the most prevalent of which are attention-deficit/hyperactivity disorder (ADHD), irritability, anxiety, and intellectual disability. Medical comorbidities are also more common in individuals with ASD, including gastrointestinal disorders, sleep disturbances, seizures and epilepsy, and immune system dysregulation. Behavioral interventions, particularly early in the developmental period, are considered the mainstay treatment for ASD. Psychotropic drugs are commonly used to treat symptoms associated with ASD, but only two have been approved by the Food and Drug Administration (FDA): risperidone and aripiprazole, both for the treatment of irritability. This chapter will cover how ASD is diagnosed, what the most common psychiatric and medical comorbidities are, and the most recent treatment data.