In a study supported by the Baily Thomas Charitable Fund, Cerebra and the Cornelia de Lange Syndrome Foundation UK and Ireland, a group of researchers has contrasted the relationship between anxiety and Intolerance of Uncertainty in Fragile X Syndrome (FXS) and Cornelia de Lange Syndrome (CdLS). You can read the full article by Smith et al here, but if you want a shorter version about the FXS-specific findings, please keep reading this blog. 

Approximately 30% of males with FXS meet the diagnostic criteria for a separate diagnosis of co-occurring autism. However, the subtle differences in the presentation and severity of autistic characteristics in people with FXS and CdLS compared with those with nonsyndromic autism is under-studied. For example, boys with FXS are less likely to display differences in social reciprocity (e.g., social smiling) compared with autistic boys of the same age. This suggests that, despite similarities in characteristics, nuanced differences in autism presentation may make it challenging to differentiate autism from the inherent behavioural phenotype of rare genetic syndromes, yet it also affords the opportunity to examine the relationship between profiles of autistic characteristics and anxiety.

What is the Intolerance of Uncertainty? 

The Intolerance of Uncertainty may explain the relationship between autism and anxiety in FXS. It is characterised by distress or difficulty functioning during uncertain or unpredictable situations, a strong preference for predictability, and cognitive or behavioural paralysis or inhibition. It has been identified as an important risk factor for the development and maintenance of anxiety in the general population and has been implicated as a critical factor underpinning anxiety. Understanding the relationship between the Intolerance of Uncertainty and anxiety in FXS is important for the development of tailored interventions to reduce anxiety in rare genetic syndromes associated with intellectual disability.

Findings of the study 

The results from the  study suggest that the relationship between autistic characteristics, anxiety and levels of Intolerance of Uncertainty (IU) differs for people with CdLS and males with FXS. While the CdLS and FXS groups did not differ in autistic characteristics, anxiety symptom severity or levels of IU, levels of IU fully mediated the relationship between autism characteristics and anxiety symptom severity for the CdLS group, but not for the FXS group. This means that when compared to the effects of IU in those with FXS, participants with CdLS showed greater levels of IU impact in the relationship between autism and anxiety.These findings improve our understanding of the autism–anxiety relationship and can inform future research directions, as well as potential new interventions and theoretical frameworks, improving quality of life for individuals with rare genetic syndromes and their families.