Anxiety, Distress, and Repetitive Behaviors in ASD, Anxiety Disorder, and Typical Development

Background: Repetitive behaviors have been associated with DSM-defined anxiety in ASD using parent-report measures (Rodgers et al., 2012).  However, this association has not yet been well studied using gold-standard, clinician directed measures of anxiety.  It also has not been determined whether a similar association exists in individuals without ASD.  Secondarily, some individuals with ASD experience high levels of anxiety-related distress and/or anticipatory worry around ASD-related challenges, such as difficulty with transitions, changes in routine, or exposure to social settings (Kerns et al., under review).  This atypical distress may be a manifestation of anxiety in ASD that is not well represented in the DSM. We hypothesize that this atypical distress, like DSM-defined anxiety, may be associated with increased levels of impairing repetitive behaviors.  In our studies of anxiety, we systematically differentiate DSM-anxiety from atypical distress often seen in ASD to provide a clearer discrimination of children with ASD and possible anxiety. 

Objectives: To determine if repetitive behaviors are associated with anxiety in general, and if they are differentially associated with DSM-defined anxiety and the atypical distress often seen in ASD. 

Methods: This ongoing study currently includes 67 children with or without ASD (ages 7-17). DSM-anxiety was assessed with the Anxiety Disorders Interview Schedule (ADIS); an addendum to the ADIS was designed to assess Atypical Distress. Caregivers also completed the Repetitive Behavior Scale - Revised (RBS-R). Participants fell into one of the following groups: Typically Developing Control (TDC); Anxiety Only (no ASD); ASD Only; and ASD+Anxiety (with specifiers DSM-Anxiety or Atypical Distress).  Groups did not differ on age or IQ, as measured by the DAS-II.  Separate DSM-anxiety and Atypical Distress severity scores were calculated for each participant using an algorithm to combine clinician severity ratings for DSM-IV anxiety and for atypical distress, respectively.

Results: One-way ANOVA analyses to date indicated a significant difference between groups on the RBS-R Overall Items Endorsed (p<.001).  Post-hoc analyses showed that the TDC group was significantly lower than all other groups (M=1.4); while the Anxiety Only and ASD Only groups showed similar rates of repetitive behavior (M=9.6;M=9.9); and the ASD+Anxiety group had significantly higher levels of repetitive behaviors compared to all groups (M=15.6).  To further explore the relationship between anxiety and repetitive behaviors in the ASD group, correlations between the RBS-R Overall Items Endorsed, DSM-anxiety severity score, and Atypical Distress severity score were computed.  The RBS-R Overall Items Endorsed was significantly correlated with Atypical Distress severity score (r=.50;p<.01).

Conclusions: Results suggest that individuals with clinical levels of anxiety demonstrate increased repetitive behaviors.  This phenomenon was present among individuals with and without ASD. The higher rate of repetitive behaviors in the ASD+Anxiety group may reflect either the unusual manifestation of anxiety in some youth with ASD (e.g. atypical distress) or the potential overlap of atypical distress and repetitive behavior symptoms. It could also be that the RBS-R is capturing anxiety in addition to its intended purpose of capturing repetitive behaviors. Understanding the similarities and differences between atypical distress and DSM-defined anxiety is important for clinical care and research.