Abstract/Summary

Sensory reactivity differences are commonly experienced by autistic individuals, including sensory hyperreactivity (i.e., strong reactions to sensory input), hyporeactivity (i.e., no, or slower reactions to sensory input), and seeking (i.e., fascination or fixation with sensory input). Sensory hyperreactivity can be particularly distressing and has previously been linked to anxiety in autism, and intolerance of uncertainty (IU) has been suggested to be an interlinking transdiagnostic construct. However, limited research has included sensory hyporeactivity or seeking, or examined links to certain anxiety symptomology, and research in young children and adults is especially lacking. Therefore, the four studies presented in this thesis had the primary aim of 1) elucidating the relationship between sensory reactivity difference and anxiety symptomology in autistic individuals, and secondary aims of 2) understanding the role of IU in this relationship, and 3) understanding more about the sensory experiences of autistic adults. The first study examined the relationship between sensory reactivity differences and anxiety in autistic children ages 3 – 14 years; the second study examined the relationship between sensory reactivity differences, anxiety, and IU in preschool-age autistic children ages 3 – 5 years; the third pair of studies examined the relationship between sensory reactivity differences, anxiety, and IU in autistic adults ages 18+ years; and the final study, examined the sensory experiences of autistic adults using a coproduced, mixed-methods approach. The findings robustly support an association between sensory hyperreactivity and anxiety symptomology in autistic individuals, and most notably, a consistent relationship across studies with separation anxiety. Furthermore, IU was found to be a mediating factor associated with anxiety and sensory hyperreactivity in children and adults. Although sensory hyporeactivity and seeking were linked with anxiety in some studies, this was not consistent across the studies. The findings from the mixed methods study provided enriched insights into the findings in this thesis from the perspective of autistic adults and highlighted the complex nature of sensory reactivity differences. This informed the creation of an enhanced model, which could further guide future directions. Overall, the results in this thesis advance understanding of the relationship between sensory reactivity differences and anxiety symptomology. Understanding the risk factors for anxiety in autism has importance for the development and adaptation of effective interventions for autistic children and adults.