Repetitive Thoughts and Behaviors in Autism Spectrum Disorder: A Symptom-Based Framework for Novel Therapeutics.

While the core symptoms of autism spectrum disorder include repetitive thoughts and repetitive behaviors, repetitive phenomena also occur in many other psychiatric disorders. Types of repetitive thoughts include preoccupations, ruminations, obsessions, overvalued ideas, and delusions. Types of repetitive behaviors include tics, stereotypies, compulsions, extrapyramidal symptoms, and automatisms. We provide a description of how to recognize and classify different types of repetitive thoughts and behaviors in autism spectrum disorder, providing clarity on which phenomena should be considered a core feature of autism spectrum disorder and which phenomena are indicative of a comorbid psychiatric disorder. Clinical features that can be used to differentiate types of repetitive thoughts include whether they are distressing and the degree of insight the individual has, while repetitive behaviors can be classified based on whether they are voluntary, goal-directed/purposeful, and rhythmic. We present the psychiatric differential diagnosis of repetitive phenomena within the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) framework. Careful clinical consideration of these transdiagnostic features of repetitive thoughts and behaviors can improve diagnostic accuracy and treatment outcomes, and influence future research.