Key Individual Characteristics Related to Circumscribed Interests in Youths with ASD

Background:  Circumscribed interests (CI) are a specific type of repetitive behavior that commonly occurs in youths with autism spectrum disorder (ASD), involving intense focus on a narrow range of topics (e.g., collecting objects, memorizing facts). Youth invest considerable time in activities involving these interests, often at the expense of prosocial activities. Interfering with these interests can be an antecedent for disruptive behaviors (e.g., physical aggression), often leading parents to describe these interests as their child’s most impairing symptom. Though studies have examined prevalence and delineated categories of CI, less research has examined phenotypic characteristics associated with types of CI. 

Objectives: The current study aimed to examine key phenotypic characteristics (e.g., youth intelligence, ASD core symptoms) in relation to types of CI in a large, well-characterized sample of youths with ASD. This study explores possible links between individual characteristics and CI as reported by parents. 

Methods:  The sample consisted of caregivers (n = 186) who completed the Autism Diagnostic Interview - Revised (ADI-R) as part of the Simons Simplex Collection. Caregiver responses on the “circumscribed interests” and “unusual preoccupations” items of the ADI-R were transcribed. Only participants who endorsed pervasive or disruptive interests on these items were included. Using qualitative methodology, transcriptions were coded by selecting dialogue that described CI (e.g., “obsessed with Pokémon cards”) and placing responses into categories (e.g., Collecting). Categories were derived from examination of the responses and considering existing measures of youth interests (e.g., The Interest Scale, Cambridge University Obsession Questionnaire). Individual phenotypic data were then associated with the various categories to examine characteristics of individuals with the purported interest.

Results:  Interests were grouped into 31 categories, which were consistent with those found in other studies (e.g., Bodfish, 2003; Klin et al., 2007).. Caregivers reported their child’s interests falling into an average of 2.8 categories. The most frequent interests reported were Strong Attachment to Fictional Characters (12%) and Televisions/Movies (10%). The least frequent reported were Mechanical Systems (0.4%) and Religion/Occult (0.6%).  Youth with mean IQs in the average or above average range endorsed interests such as Building/Construction, Factual Information, and Biology, whereas youth with mean IQs in the impaired range endorsed interests in Rocks/Geology. Those with a high degree of core ASD symptoms by parent report had interests ranging from Religion/Occult, to Fictional Universes, Collecting, and Weather/Natural Disasters. Those with a high degree of core ASD symptoms by clinician report had interests ranging from the Signs, to Mechanical Systems, Reading/Writing, and Music. Older youth endorsed interests in Japanese Culture, Rocks/Geology, and Factual Information, whereas younger youth endorsed interests in Words/Letters and Math/Counting.

Conclusions:  Youth with ASD endorse a broad range of CI. Specific interests are endorsed more frequently than others and certain types of interests appear to be associated with level of intelligence and core ASD symptoms, though this may differ based on parent or clinician observation. Further understanding of the etiology and types of CI and how interests relate to phenotypic characteristics will contribute to better evaluating and reducing impairment for individual youth.