Abstract
OBJECTIVE: Repetitive behaviors in autism spectrum disorders (ASD) range from motor stereotypy to immersion in restricted interests. The modified Children's Yale-Brown Obsessive Compulsive Scale for children with autism spectrum disorder (CYBOCS-ASD) includes a Symptom Checklist (behavior present or absent) and 5 severity scales (Time Spent, Interference, Distress, Resistance and Control). METHOD: We assembled CYBOCS-ASD data from 3 Research Units on Pediatric Psychopharmacology Autism Network trials to explore the component structure of repetitive behaviors in children with ASD. Raters trained to reliability conducted the CYBOCS-ASD in 272 medication-free subjects. Fifteen Symptom Checklist items were endorsed for less than 5% of the sample and were dropped. Principal component analysis was used to explore the clustering of 23 checklist items. Component scores computed for each subject were correlated with other measures. We also examined the distribution of severity scales. RESULTS: The subjects (229 boys and 43 girls; mean age = 7.8 ± 2.6 years) met criteria for an ASD; half were intellectually disabled. The PCA resulted in a 5-component solution to classify repetitive behaviors (34.4% of the variance): hoarding and ritualistic behavior; sensory and arranging behavior; sameness and self-injurious behavior; stereotypy; restricted interests. Sensory and arranging and stereotypy components were associated with lower adaptive functioning (Pearson r = 0.2-0.3; p < .003). The resistance scale showed little variation, with more than 60% of the sample with the highest score. CONCLUSIONS: Rarely endorsed items can be dropped from the Checklist. The resistance item does not appear to be relevant for children with ASD.