Sensory Sensitivity and Intolerance of Uncertainty Separately Influence Anxiety in Adults with Autism Spectrum Disorders

Background: Anxiety affects at least 50% of adults with autism spectrum disorders (ASD) and can lead to significant impairment in day-to-day life for these individuals and their families. In addition, an increase in ASD traits is linked with an increase in anxiety. Research has sought to elucidate the mechanisms by which ASD traits influence an individual’s anxiety in order to provide context and support for interventions. Two factors that have emerged as potentially influential are sensory sensitivities (SS) and intolerance of uncertainty (IU). SS can make the natural environment of an individual with ASD more challenging to experience and can even result in physical pain. IU can be distressing and lead to negative evaluation as well as influence restricted/repetitive behaviors. While both SS and IU have been shown to influence anxiety, research has not yet looked at their influence together in an adult ASD population.

Objectives: We examined the influence of SS and IU on anxiety in adults with ASD using structural equation modeling (SEM). We assessed whether SS and IU can exert this influence alone and what level of influence they have.

Methods: A dimensional sample consisting of 214 typically developing adults and 71 adults with a confirmed diagnosis of ASD completed self-report questionnaires. ASD traits were identified using the Autism Spectrum Quotient (AQ), IU was identified using the Intolerance of Uncertainty Scale – Short Form (IUS-12), sensory sensitivity was assessed using the Adolescent/Adult Sensory Profile (AASP), and anxiety was identified using the Penn State Worry Questionnaire (PSWQ).

Results: The first SEM analysis supported the hypothesis that SS and IU play a mechanistic role in the relationship between ASD traits and anxiety. The relationship between ASD traits and anxiety was significant when modeled individually but this relationship was eliminated by adding SS and IU as mediators (explaining 33.6% and 54.3% of the influence, respectively). Neither mediated the relationship when included individually. The second SEM analysis attempted to model the influence of SS, IU, and ASD traits on anxiety. All factor loadings were in the expected direction and there was converging evidence for excellent model fit. This model suggested that SS and ASD traits largely operate on anxiety via IU with SS still having a direct influence on anxiety. Importantly, including SS and IU in the model removed the direct influence of ASD traits on anxiety. Finally, replicating previous research that looked at whether anxiety itself mediates the influence of IU on SS, but with an adult population, showed a small influence of anxiety which was more pronounced in an ASD-only population.

Conclusions: The influence of ASD traits on anxiety operates via IU. Both SS and IU are necessary to explain this influence. Our model suggests that both SS and IU largely explain increases in anxiety and that SS functions both independently and through IU. This provides further evidence for the importance of addressing these specific challenges in order to reduce anxiety and the impairment associated with it.