Modeling the relationships between intolerance of uncertainty, autistic symptoms, and anxiety in autistic and non-autistic adults

Abstract Autistic adults often report difficulties dealing with uncertain situations, potentially due to atypical predictive mechanisms. In this context, they show heightened intolerance of uncertainty (IU), defined as a tendency to perceive uncertainty as distressing. This study examined how intolerance of uncertainty relates to autistic traits and symptoms, anxiety, and sleep quality, and compared two models of these relationships. A total of 384 adults, including 68 autistic individuals, completed seven questionnaires assessing IU, autistic traits, social and non-social autistic symptoms, anxiety and sleep quality. Correlation matrices were computed across and within diagnostic groups. Structural equation modeling compared a Neurodevelopmental Model , which posits directional paths from autistic traits to core symptoms and IU, with an Evolutionary Stress Model , which posits an alternative ordering of these constructs. Logistic regression analyses evaluated whether combinations of questionnaire scores could distinguish autistic from non-autistic participants. Autistic adults reported higher IU, anxiety, and sleep difficulties, alongside elevated autistic traits and symptoms. All questionnaire measures were positively correlated, with particularly strong associations between IU and autistic traits, social difficulties and repetitive behaviors, and anxiety. Structural equation modeling supported the Neurodevelopmental model , in which autistic traits preceded core autistic symptoms and IU, which were in turn specified as predicting anxiety and sleep difficulties. These relationships varied by group and gender. Finally, combining measures of autistic traits, IU, and anxiety yielded high classification specificity. These findings, discussed within the predictive coding framework, highlight the central role of IU in autism, as well as the contribution of anxiety and sleep issues. They underscore the need to develop strategies and programs to alleviate these difficulties.