Examining the Impact of Repetitive and Restricted Behaviors on Adaptive Functioning of Children with ASD

Background:  Restricted and repetitive behaviors (RRBs) include a broad category of behaviors which are considered core characteristics required for a diagnosis of Autism Spectrum Disorder (ASD) according to the Diagnostic and Statistical Manual (DSM-V; American Psychiatric Association, 2013). RRBs can be subdivided into Repetitive and Sensory Motor behaviors (RSM) and Insistence on Sameness behaviors (IS). In previous studies, researchers found significant negative correlations between IQ and RSM behaviors and positive correlations between IQ and IS behaviors (Richler et al. 2010). Bishop et al. (2006) found stronger relationships between RRBs and IQ with increasing age in children with ASD. However, earlier research may be difficult to generalize, since those studies tended to focus on a limited number of RRBs, measured predominantly by tools designed for assessing ASD and not RRB’s per se. This study uses a newly standardized measure, the Behavior and Sensory Interest Questionnaire (BSIQ) to classify a wide range of RRBs. Furthermore, subject characteristics such as age, cognitive and adaptive functioning, gender and autism severity will be utilized to compare children with high and low RRBs.

Objectives:  By utilizing the BSIQ, this study aims to compare a wide range of RRBs and there relationship to subject characteristics (age, cognitive and adaptive functioning, gender and autism severity). In addition, the total and type of RRBs will be examined.

Methods:  A sample of 237 children with ASD (85% male; NVIQ=93.7, SD=20) was drawn from the Simons Simplex Collection and the Boston Autism Consortium. Participants ages were between 27-272 months, (mean=94.9, SD=49.6). The BSIQ, designed to evaluate the number, type, and intensity of RRBs, was administered to a parent. Testing also included child cognitive, behavioral and adaptive functioning assessments. Generalized linear models were employed to explore the relationship between different subject characteristics, cognitive functioning and RRBs. 

Results:  Analyses revealed a significant weak negative trend of age on RSM behaviors (p=0.004) when controlling for IQ, however no significant trend was revealed of age on IS behaviors. It is important to note that a significant interaction of age and IQ was found for RSM but not IS behaviors. Furthermore, RSM behaviors had a significant negative impact on overall adaptive behaviors as measured by the Vineland composite standard score (p=0.02) however the same effect was not observed with IS behaviors (p=0.51). All analyses were controlled for IQ, age and gender. 

Conclusions:  Expanding on previous research, we employed a more comprehensive measure to observe the impact of age and IQ on RRB’s.  We found significant effects of RSM but not IS on adaptive functioning. Further research is necessary to determine which adaptive behavior subdomains are directly impacted by RSM and not IS behaviors. Furthermore it’s important to determine if RRB severity differentially affects adaptive functioning to attempt to understand the impact of RRB’s on the functioning of children with ASD.