Repetitive Behavior Severity as an Early Indicator of Risk for Elevated Anxiety Symptoms in Autism Spectrum Disorder

OBJECTIVE: A significant proportion of children with autism spectrum disorder (ASD) will develop an anxiety disorder during childhood. Restricted and repetitive behavior severity in ASD positively correlates with anxiety severity in cross-sectional surveys. The longitudinal relationship between restricted/repetitive behavior and future anxiety symptoms is unclear. METHOD: In a longitudinal cohort of children with ASD (n = 421), restricted/repetitive behavior severity at enrollment (age 2-5 years) was categorized as "mild," "moderate," or "severe" using the Autism Diagnostic Interview-Revised. Elevated anxiety symptoms were defined by a Child Behavior Checklist (parent report) Anxiety subscale T-score of >65 at ages 8 to 11 years. Multivariable logistic regression with multiple imputation for missing data was used to examine the association between restricted/repetitive behavior severity and elevated anxiety symptoms while adjusting for age, sex, adaptive functioning, baseline anxiety, income, and parenting stress, generating adjusted odds ratios (aORs) and 95% CIs. RESULTS: Approximately 58% of children with severe restricted/repetitive behavior at enrollment had elevated anxiety symptoms by age 11, compared to 41% of those with moderate, and 20% of those with mild restricted/repetitive behavior, respectively. Moderate and severe restricted/repetitive behavior were both associated with increased odds of elevated anxiety (moderate aOR: 2.5 [1.2-5.3]; severe aOR: 3.2 (1.4-7.5]). CONCLUSION: Restricted/repetitive behavior severity at time of ASD diagnosis indicates risk for future anxiety symptoms. This finding increases our understanding of which children with ASD will develop anxiety disorders and may guide research concerning early interventions and etiological mechanisms.