Interests in high-functioning autism are more intense, interfering, and idiosyncratic than those in neurotypical development.

Although circumscribed interests are pathognomonic with autism, much about these interests remains unknown. Using the Interests Scale (IS), this study compares interests between 76 neurotypical (NT) individuals and 109 individuals with high-functioning autism spectrum disorder (HF-ASD) matched groupwise on age, IQ, and gender ratio. Participants and their parents/caregivers completed diagnostic measures (the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule; HF-ASD only), cognitive tests (Wechsler IQ Scales), and questionnaires (the Repetitive Behavior Scale-Revised, the Behavior Rating Inventory of Executive Function, and the Social Responsiveness Scale), in addition to the IS. Consistent with previous research, HF-ASD and NT individuals did not differ in number of interest areas, but the types of interests and intensity of those interests differed considerably. Using only the IS intensity score, 81% of individuals were correctly classified (NT or HF-ASD) in a logistic regression analysis. Among individuals with HF-ASD, Interests Scale scores were significantly related to Autism Diagnostic Observation Schedule, Behavior Rating Inventory of Executive Function, Repetitive Behavior Scale-Revised, and Social Responsiveness Scale scores, but they were not related to Autism Diagnostic Interview-Revised scores, IQ, gender, age, or psychotropic medication use. The type and intensity, but not the number, of interests distinguish high-functioning individuals with ASD from NT individuals.