Exploring the Relationship between Stereotypy, Sensory-Driven Behaviors, and Self-Injury in Children with Autism Spectrum Disorder

Background: The DSM-V categorizes stereotyped movements and hyper- or hypo-reactivity to sensory input as subtypes of restricted and repetitive behaviors (RRBs), a defining characteristic of Autism Spectrum Disorder (ASD) (American Psychiatric Association, 2013). Self-injurious behaviors (SIBs) are also seen at high rates in this population and can cause significant impairment (Minshawi et al., 2014). SIBs have been theorized by some to be an extreme form of RRBs (Eynat, Dyck, & Passmore, 2009; Mace et al., 1994). While there is research examining factors that influence SIBs, no study has examined the relationship between stereotypy and sensory-driven behaviors and SIBs in the ASD population.

Objectives: The study aims were to 1) examine the relationship between stereotypy and SIBs, 2) examine the relationship between sensory-driven behaviors and SIBs, and 3) determine predictors of SIBs.

Methods: Data from 220 children with ASD ages 2.5–16.9 years enrolled in a previous research through Boston Children’s Hospital and the Boston Autism Consortium was used. All children met diagnostic cutoff on the Autism Diagnostic Observation Schedule (ADOS, Lord et al., 2003). The Behavior and Sensory Interest Questionnaire (BSIQ, Hanson et al., 2016) measures type and severity of 74 RRBs with codes ranging from 0-3. Using the averages of BSIQ questions related to stereotypy and sensory RRBs, four groups were developed: 1) stereotyped movements (SM) (Items B1.a-B4.f), 2) unusual sensory interests (SI) (Items B5.a-k), 3) sensory aversions (SA) (Items B6.a-d), and 4) SIBs (Items E1.a-g). The first three groups were then divided into three levels of severity: Low severity=scores below the 25^th percentile, Moderate severity=scores ranging from the 25^th to 75^th percentile, and High severity=scores above the 75^th percentile. Analysis was conducted by first using Spearman rank order correlations to identify relationships between SM, SI, SA and SIBs. Next, a Kruskal-Wallis test was used to determine if there was a significant difference in SIBs for low, moderate, and high levels of SM, SI, and SA. Lastly, a linear regression model was run to determine any predictors of SIBs controlling for nonverbal IQ (NVIQ), age, and gender.

Results: All groups were positively correlated with SIBs (SM, SI, SA; p<.001). There was also a significant difference in SIBs between the different severity groups. Post hoc testing showed that SM high (p=.002), SI high (p<.001) and SA high (p=.029) were significantly correlated with SIBs. There was no significance for SM, SI, SA moderate or low severity and SIBs. SA was the only significant predictor of increased SIBs (r =.102, p<.001).

Conclusions: The results indicate that high severity levels of increased stereotypy, sensory-seeking behavior, and sensory aversion are all associated with SIBs. This could support the hypothesis by Eynat et al., 2009 that these behaviors are related. In addition, SA was a predictor of SIBs. Individuals who experience distress and aversions to specific sensory stimuli (BSIQ Items B6.a-d), could potentially show this by engaging in SIBs. In the future, more research will be critical to understand the causes and relationships of these behaviors and how best to design intervention approaches.