Differential diagnosis of autism spectrum disorder

1. Diagnostic Issues and Complexities in Autism and Related Conditions - Fred R. Volkmar, Marc Woodbury-Smith, Suzanne L. Macari, and Roald A. Øien - 2. Autism Spectrum Disorder Versus Intellectual Disability - Jan Blacher, Bruce L. Baker, and Christine T. Moody - 3. Autism Spectrum Disorder Versus Communication Disorders - Rhea Paul - 4. Autism Spectrum Disorder Versus Attention-Deficit/Hyperactivity Disorder - Naomi O. Davis, Kimberly L. H. Carpenter, and Geraldine Dawson - 5. Autism Spectrum Disorder Versus Conduct Problems - Chardée Galán and Carla Mazefsky - 6. Autism Spectrum Disorder Versus Anxiety Disorders - Mikle South, Alexis Brewe, Connor M. Kerns, and Susan White - 7. Autism Spectrum Disorder Versus Major Depressive Disorder - Katherine K. M. Stavropoulos, Yasamin Bolourian, and Katherine Gotham - 8. Autism Spectrum Disorder Versus Obsessive-Compulsive Disorder and Tourette's Disorder - Morgan M. McNeel, Stacey C. Grebe, Rebecca J. Clayton, Sophie C. Schneider, Andres G. Viana, Sarah S. Mire, Yasmine Omar, Wayne K. Goodman, and Eric A. Storch - 9. Autism Spectrum Disorder Versus Posttraumatic Stress Disorder - Sonja Saqui, Brigid Garvin, and Connor M. Kerns - 10. Autism Spectrum Disorders Versus Genetic Syndromes - Jamie Capal and Shafali Jeste - 11. Clinical Decision-Making in Evidence-Based Assessment: Disentangling Co-Occurring and Differential Diagnoses in Individuals With Autism Spectrum Disorder - Rebecca Elias and Catherine Lord - About the Authors - Index

Although cases of autism can, in retrospect, be identified before Kanner's 1943 classic report (also see Donvan and Zucker 2016), it was Kanner's genius to put together the core features that we continue to associate with autism; autistic aloneness and restricted interests/difficulties with change. This description was straightforward and atheoretical and has stood the test of time even as we debate the boundaries of autism today. The early years following Kanner's initial presentation were plagued by a lack of consistency in diagnosis and several mistaken beliefs about autism, e.g., associations with childhood schizophrenia and inappropriate parenting. This changed dramatically in the 1970s as three lines of evidence helped establish the validity of autism as a diagnostic concept: These included: 1) the awareness that autism was a brain-based disorder associated with high rates of epilepsy with peaks of onset in early childhood and adolescence, 2) the first twin studies of autism made it clear that there was a very strong genetic component of autism with high concordance in MZ twins, and 3) children with autism responded best to structured teaching rather than unstructured psychotherapy (see Jackson and Volkmar, 2019 for a discussion)