DSM-IV included several diagnoses under the category of pervasive developmental disorders, including Asperger’s disorder, which had autistic features without an intellectual disability (American Psychiatric Association, 2000). This new diagnostic category increased awareness of who was on the autism spectrum and also led to more people receiving an autism spectrum diagnosis. DSM-5 no longer distinguishes between different types of ASD (e.g., Asperger’s disorder, autistic disorder or pervasive developmental disorder not otherwise specified); instead, a person can have ASD with or without intellectual disability
Many adults with ASD also have a comorbid psychiatric disorder, such as attention-deficit/hyperactivity disorder, anxiety or depression.
Diagnosis requires a more comprehensive assessment, typically conducted by a specialist, such as a psychologist, developmental pediatrician or psychiatrist with expertise in ASD. The assessment usually involves a structured diagnostic interview with the patient or parent (e.g., Autism Diagnostic Interview – Revised (Lord et al., 1994), as well as clinical observation (e.g., Autism Diagnostic Observation Schedule) (Lord et al., 2000).