Relationships Among Restricted Interests and Repetitive Behaviors, Internalizing and Externalizing Symptoms, and Oral Language in ASD

Background: Up to 72% of children with autism spectrum disorder (ASD) have at least one comorbid internalizing (e.g., anxiety) or externalizing (e.g., ADHD) disorder. Varying oral language abilities are related to different comorbid psychiatric symptoms. However, little is known about how oral language relates to restricted interests and repetitive behaviors (RRBs) and comorbid internalizing or externalizing symptoms. Even less is known about how different types of RRBs (i.e., “insistence on sameness” [IS] and “repetitive and sensorimotor behaviors” [RSM]) impact symptom manifestation. Understanding interactions between these RRBs and comorbid internalizing and externalizing symptoms may elucidate clinical presentation and inform more effective ASD interventions.

Objectives: To examine how oral language affects relationships between specific RRBs, internalizing and externalizing symptoms.

Methods: Data were analyzed from a subsample of children in Phase 1 Simons Variations in Individuals Project (Simons VIP) (52% male; ages 6-18 years old) who had 16p11.2 deletions/duplications or 1q21.1 deletions/duplications + ASD (N=90). Two types of RRBs (RSM, IS) were measured using the Behavior and Sensory Interests Questionnaire (BSI). Oral language was measured via the Comprehensive Assessment of Spoken Language (CASL), and caregiver-reported internalizing (INT) and externalizing (EXT) symptoms were measured with the Child Behavior Checklist (CBCL/6-18). CASL oral language ability was examined as a potential moderator of RSM and IS with INT and EXT, respectively.

Results: Overall, BSI RSM scores were in the higher range (M=9.66, SD=8.62), while BSI IS scores were in the lower range (M=5.50, SD=6.20) compared to scores in the validation study. Mean CASL core composite standard scores were in the lower borderline range (M=74.19, SD=17.21). Mean CBCL T-scores were in the average range for INT (M=56.45, SD=10.78) and elevated for EXT (M=61.26, SD=10.60). Four multiple regression models were estimated using BSI scores (IS, RSM) as predictors of INT and EXT scores, respectively. CASL scores were included as potential moderators. In the two multiple regression models for INT scores, results were significant for both types of RRBs: RSM: R²=.100, F (3,86)=3.19, p=.03; IS: R²=.09, F (3,86)=2.89, p=.04. For EXT scores, regression model results were not significant. RSM predicted INT (β=.29, p<.01) and EXT (β=.23, p=.04). IS scores predicted INT (β=.27, p<.01) but not EXT (β=.21, p=.06). CASL scores did not moderate the relations of RSM and IS with EXT and INT, respectively.

Conclusions: Findings revealed that both types of RRBs predicted internalizing symptoms in children with ASD. Children with high RSM had more internalizing and externalizing symptoms; however, IS predicted only internalizing symptoms. Contrary to our hypothesis, children’s oral language ability did not moderate the association between RRBs and either internalizing or externalizing symptoms. It is possible that this relates to the overall low oral language ability in our relatively small sample. However, findings are nuanced, and the forthcoming examination of specific types of internalizing (anxious/depressed, withdrawn, somatic complaints) and externalizing symptoms (rule-breaking, aggressive behaviors) or of facets (index scores) of oral language ability will provide further information about relationships between these domains. Additional analyses will also examine these relationships between the duplication+ASD and deletion+ASD groups.