Behavioural and physiological indicators of anxiety reflect shared and distinct profiles across individuals with neurogenetic syndromes

The effect of anxiety and autism symptom severity on restricted and repetitive behaviors over time in children with fragile X syndrome

BACKGROUND

Restricted and repetitive behaviors (RRBs) are highly prevalent and reduce function in individuals with fragile X syndrome (FXS). As transdiagnostic features of intellectual disability, elevated rates of RRBs in FXS could represent various underlying known co-occurring conditions in FXS such as anxiety or autism spectrum disorder (ASD), yet this distinction has not been investigated. Further, delineating whether RRBs are more indicative of anxiety or ASD in FXS may clarify phenotypic profiles within FXS and improve differential assessment.

METHODS

We longitudinally examined the potentially independent or multiplicative effect of ASD and anxiety symptom severity on RRBs in 60 children with FXS. Anxiety was measured using the Child Behavior Checklist (CBCL), ASD severity was measured using the Childhood Autism Rating Scale (CARS), and RRBs were measured using the Repetitive Behavior Scale - Revised (RBS-R). We estimated a series of moderated regression models with anxiety and ASD symptoms at the initial assessment (Time 1) as predictors of RRBs at the outcome assessment two years later (Time 2), along with an anxiety-by-ASD interaction term to determine the potential multiplicative effect of these co-occurring conditions on RRBs.

RESULTS

Results identified a significant interaction between ASD and anxiety symptom severity at the initial assessment that predicted elevated sensory-motor RRBs two years later. Increased sensory-motor RRBs were predicted by elevated ASD symptoms only when anxiety symptom severity was low. Likewise, increased sensory-motor RRBs were predicted by elevated anxiety symptoms only when ASD symptom severity was low. Interestingly, this relationship was isolated to Sensory-Motor RRBs, with evidence that it could also apply to total RRBs.

CONCLUSIONS

Findings suggest that ASD and anxiety exert independent and differential effects on Sensory-Motor RRBs when at high severity levels and a multiplicative effect when at moderate levels, which has important implications for early and targeted interventions.

Development and psychometric properties of the Clinical Anxiety Scale for People with Intellectual Disabilities (ClASP-ID)

BACKGROUND

There is a critical need for the development of dependable and valid anxiety assessment tools suitable for people with moderate to severe intellectual disabilities, particularly those who speak few or no words. Distinguishing anxiety from distress caused by physical discomfort (pain) or characteristics associated with autism, prevalent in this population, necessitates specialised assessment tools. This study (a) developed a parent-report anxiety questionnaire tailored for individuals with severe to moderate intellectual disabilities, potentially with a co-diagnosis of autism, and (b) evaluated the psychometric attributes of this novel measure.

METHODS

A comprehensive approach involving literature reviews, inspection of existing tools, and interviews with clinicians and parents guided the creation of the Clinical Anxiety Scale for People with Intellectual Disabilities. The tool was completed by parents or caregivers (N = 311) reporting on individuals aged 4 or older with intellectual disabilities.

RESULTS

Exploratory factor analysis indicated a four-factor structure encompassing anxiety, pain, low energy/withdrawal, and consolability. The anxiety factor explained the most variance in scores (26.3%). The anxiety, pain, low energy/withdrawal subscales demonstrated robust internal consistency (α = 0.81-0.92), and convergent, divergent, and discriminant validity. Robustness of these subscales was further evidenced by test-retest reliability (ICC = 0.79-0.88) and inter-rater reliability (ICC = 0.64-0.71). Subgroup analyses consistently demonstrated strong psychometric properties among individuals diagnosed with non-syndromic autism (N = 98), children (N = 135), adults (N = 175), and across diverse communication abilities within the sample. Moreover, individuals diagnosed with both autism and anxiety exhibited significantly higher scores on the anxiety subscale compared to those without an anxiety diagnosis, while showing no difference in autism characteristic scores.

CONCLUSIONS

The findings indicate that the Clinical Anxiety Scale for People with Intellectual Disabilities is a promising measure for use across diverse diagnostic groups, varying communication abilities, and with people with moderate to severe intellectual disabilities.