The Influence of Atypical Sensory Processing and Anxiety on ASD Symptomatology

Background: Restricted interests and repetitive behaviors (RIRBs) are a defining feature of autism spectrum disorder (ASD). These symptoms can be divided into three distinct constructs: insistence on sameness (I/S), repetitive motor behaviors (RMB) and sensory processing abnormalities. High rates of co-morbid anxiety in ASD have been linked to both I/S and RMB, yet conflicting findings suggest that atypical sensory processing may also play a role in the relationship, particularly with I/S.

Objectives: This novel investigation had 2 goals:

1. Determine if the contribution of atypical sensory processing in ASD to I/S and anxiety varies depending on sensory phenotype (hyper- or hypo-sensitive, sensory avoiding or seeking) and specific type of anxiety.
2. Compare these relationships between individuals with ASD and typically-developing (TD) children.

Methods: Parents of 87 children (ASD, n=49, M_age=12.0 years, SD=3.1; TD, n=38, M_age=11.6 years, SD=3.1, data collection ongoing) completed questionnaires reporting on sensory processing (the Sensory Profile-2), I/S (the Repetitive Behavior Questionnaire-2), and anxiety (the Spence Children’s Anxiety Scale). A two-step analysis was undertaken:

1. A correlational analysis was used to investigate the relationships between variables in both the ASD and TD group, then correlations were compared across groups to highlight between-group differences.
2. A hierarchical regression was run to examine the unique contributions of atypical sensory processing and anxiety to I/S in the ASD group.

Results:

Correlational analysis

The correlational analysis revealed significant differences between ASD and TD groups for anxiety subscales and I/S, and anxiety subscales and sensory sensitivity (Figure 1). Specifically, significantly different correlations were observed between I/S and separation anxiety (p=.03, z=2.15), I/S and panic (p=.01, z=2.47), I/S and general anxiety disorder (p=.05, z=1.91), I/S and total anxiety symptoms (p=.02, z=2.33), as well as between separation anxiety and sensory sensitivity (p=.05, z=1.93). Neither social anxiety, physical anxiety, nor obsessive compulsive disorder were significantly different for correlations with I/S or sensory sensitivity when compared between groups.

Hierarchical regression

In the hierarchical regression, we explored which variables significantly predicted the occurrence of I/S symptomatology (Table 1). I/S was significantly predicted by the sensory phenotype of hypersensitivity (β=.34, t=2.86, p=.007) and the subscale of separation anxiety(β=.252, t=2.41, p=.021). Notably, I/S decreased with age (r=-.39, p=.003).

Conclusions: Our correlative findings indicate that I/S is atypically related to three specific types of anxiety (separation, panic, and general anxiety) in individuals with ASD. The results from the hierarchical regression suggest that the expression of I/S in children with ASD varies based on a child’s level of hypersensitivity to sensory stimulation, and distress due to separation anxiety. Furthermore, younger children may demonstrate more frequent I/S behaviors. Finally, despite the numerous differences between TD and ASD groups’ relationships between sensory processing, RIRB, and anxiety, there was also a significant amount of overlap between groups, underscoring the importance of non-clinical control groups.