Intolerance of Uncertainty, but Not Anxiety, Predicts Sensory Sensitivities in Autism

Background:  

Sensory sensitivities have risen to greater prominence with their inclusion in the recent DSM-5 criteria for autism. Yet very little is known about their underlying mechanisms. Some studies have reported significant links between sensory sensitivities and another common feature of autism, anxiety, although the causal direction of this relationship is not fully understood. Alternatively, one recent theory of autism suggests that sensory sensitivities in autism might be due to fundamental differences in the way that individuals deal with an uncertain or unpredictable environment (Pellicano & Burr, 2012).

Objectives:  

Here, we investigated the relationships between children’s propensity to deal with uncertainty, their sensory sensitivities and anxiety levels. The objectives of this study were threefold. First, we investigated the relationship between sensory sensitivities with the construct, ‘intolerance of uncertainty’, a predisposition to react negatively to uncertainty on a cognitive, behavioural and emotional level (Buhr and Dugas, 2009). Second, we examined the relationship between sensory sensitivities and anxiety symptoms. Finally, we examined whether children’s anxiety levels might mediate (fully or partially) the putative relationship between intolerance of uncertainty and sensory sensitivities.

Methods:  

We administered questionnaires to parents of 65 children with autism aged between 6 and 14 years, including the Short Sensory Profile (McIntosh et al., 1999) to tap children’s sensory sensitivities, the Intolerance of Uncertainty Scale (Rodgers et al., 2012) and the Spence Children’s Anxiety Scale (Spence, 1997). Children were administered the Wechsler Abbreviated Scales of Intelligence – 2^nd Edition and the ADOS-2. We used correlation and regression analyses to examine the associations between scores on these measures.

Results:  

Sensory sensitivity scores showed a clear association with scores on intolerance of uncertainty (r = .59, p <.001) and anxiety (r = .61, p <.001). Intolerance of uncertainty scores were also strongly associated with anxiety scores (r = .78, p <.001). A hierarchical regression analysis in which anxiety scores were entered in the first step and intolerance of uncertainty scores were entered in the second step showed that intolerance of uncertainty made a unique contribution to the variance in children’s sensory sensitivities once the effects of anxiety were accounted for (R² change = .091, F change = 8.30, p = .006). In the final model, intolerance of uncertainty scores significantly predicted sensory sensitivity scores (β = .44, p = .006) but anxiety scores did not (β = .29, p = .070). Individual differences in gender, age and IQ were not associated with sensory sensitivity scores.

Conclusions:  

Sensory symptoms, anxiety and intolerance of uncertainty are robustly associated with each other in children with autism. Intolerance of uncertainty has previously been shown to predict anxiety (Boulter et al., 2014). Here, we show that it also – and uniquely – predicts sensory sensitivities. The effect of anxiety on sensory sensitivities was not upheld when both anxiety and intolerance of uncertainty were entered together as predictors in the model, suggesting that intolerance of uncertainty could potentially explain the relationship between anxiety and sensory sensitivities.