Cross-sectional study links three correlates to anxiety in moderate-to-profound intellectual disability

A community-based cross-sectional study of 165 children and adults with moderate to profound intellectual disability found that anxiety scores were consistently associated with auditory sensory processing differences, intolerance of uncertainty, and physical health difficulties. The pattern appeared in hierarchical regression models using two separate informant-rated anxiety measures, suggesting that these correlates may be relevant across diagnostic groups. The research did not establish causes, and the investigators said clinical usefulness would require validation in further studies and intervention research.

The participants ranged from 4 to 63 years old, with a mean age of 20.9 years and a standard deviation of 11.1; 92, or 55.8%, were male. Their diagnoses included autism, Angelman syndrome, Cornelia de Lange syndrome, fragile X syndrome, and a heterogeneous group of other intellectual-disability diagnoses. The inclusion criteria concentrated the sample on people with limited verbal communication or adaptive functioning: participants either spoke only “odd words” or no words, or spoke in sentences but were classified as “partly able” or “not able” on the Wessex Questionnaire.

Parents and carers completed an online questionnaire battery covering anxiety, sensory processing, repetitive behaviour, responses to uncertainty, physical health, adaptive skills, verbal ability, and autism characteristics. Measurement was a central challenge because relatively few anxiety instruments have been designed or validated for people with moderate to profound intellectual disability. Behavioural signs of anxiety can overlap with repetitive behaviour, pain, low mood, intellectual disability, and autism, and they may vary with a genetic syndrome or co-occurring diagnosis.

The researchers therefore analysed two existing instruments. The seven-item general anxiety subscale of the Anxiety, Depression and Mood Scale, or ADAMS, was the primary outcome. The anxiety subscale of the Diagnostic Assessment for the Severely Handicapped–II, or DASH-II, was used as a secondary outcome.

Both are informant-rated measures intended to capture behavioural signs of anxiety, but the two instruments did not produce identical demographic patterns. Hierarchical regression was used to test three successive levels of explanation. Diagnostic group was entered first, including autism, Angelman syndrome, Cornelia de Lange syndrome, fragile X syndrome, and a heterogeneous category for diagnoses represented by fewer than 10 participants.

Age, gender, verbal ability, adaptive self-help skills, and the Social Communication Questionnaire score were added at the second step. Sensory processing, repetitive behaviour, intolerance of uncertainty, and physical health difficulties were then introduced at the third step. For the ADAMS, diagnosis explained 14.0% of the variance in anxiety scores, while the full model explained 61.9%.

For the DASH-II, diagnosis explained only 1.2%, and the full model accounted for 48.6%. These percentages describe variation captured by statistical models, not the proportion of anxiety caused by the included variables. Auditory sensory processing differences were associated with higher anxiety scores on both measures after the researchers accounted for diagnosis, age, gender, verbal ability, self-help skills, autism characteristics, repetitive behaviour, uncertainty responses, and physical health.

Intolerance of uncertainty showed the same cross-measure association. More frequent health difficulties were also associated with anxiety on both instruments. In the ADAMS model, a measure based on the number of health problems fitted better than one based on severity, with Akaike information criteria of 383.282 and 388.124, respectively.

The DASH-II model showed the opposite pattern: the severity-based model fitted better, with an Akaike information criterion of 271.671 compared with 275.169 for frequency. Genetic diagnosis did not retain a consistent association with anxiety once other variables were included. In the initial ADAMS model, people with Angelman syndrome and those in the heterogeneous diagnosis category had lower anxiety scores than the autism reference group, while Cornelia de Lange syndrome and fragile X syndrome did not differ significantly from autism.

When the full set of predictors was added, the differences for Angelman syndrome and the heterogeneous group were no longer statistically significant. Age, gender, verbal ability, self-help ability, and autism-characteristic scores were also non-significant predictors in the final ADAMS model. In the DASH-II analysis, being female was associated with higher anxiety scores and remained significant after the later variables were added, while age was significant at the preceding step but not in the final model.

The divergence between the instruments means the demographic findings should not be treated as interchangeable. Not every plausible correlate was supported. Repetitive behaviour did not predict higher anxiety after other factors were considered in either model, and neither visual nor tactile sensory processing differences were significant predictors.

The authors noted that repetitive actions may help people manage distress or serve other purposes, such as enjoyment or attention, which could weaken an expected statistical relationship with anxiety. The sensory analysis also used only the auditory, visual, and tactile subscales of the Sensory Profile 2 rather than all six of its domains. The null findings therefore apply to these particular measured dimensions and do not show that every form of sensory difference is unrelated to anxiety.

Several design limitations restrict what can be concluded from the cross-sectional associations. Regression cannot establish whether sensory differences, responses to uncertainty, or health difficulties precede anxiety, accompany it, or arise in relation to other influences. All information was supplied by parents or carers rather than obtained through direct assessment of the participants, and most informants were mothers.

The physical-health questionnaire covered the previous month but did not record medication control, other treatment, pain specifically, or the subjective burden of illness. It was therefore an imperfect proxy for pain or health-related burden, both of which could have stronger relationships with anxiety. The study also did not examine broader environmental influences, including caregiving context, social support, and educational setting, and it could not establish temporal relationships.

The way diagnostic groups were assembled creates another limitation. People with both autism and a genetic syndrome were assigned to the syndrome group, while rare diagnoses with fewer than 10 participants were combined into a heterogeneous category. This design enabled a cross-syndrome analysis but could conceal differences among distinct conditions and between people with and without co-occurring autism.

The exploratory analysis used pre-specified, theory-driven predictors and did not apply Bonferroni or other post-hoc corrections, reducing the chance of missing smaller relationships but also leaving some findings in need of independent confirmation. The authors also called for finer analyses of rare genetic syndromes, where anxiety-related mechanisms may differ, as well as longitudinal research. Using two anxiety measures was a notable strength in a population where behavioural assessment is especially difficult.

The repeated association of auditory processing differences, uncertainty responses, and health difficulties with anxiety gives greater weight to the overall pattern than would arise from a single instrument, although it does not validate either measure as a gold standard. A newer tool, the Clinical Anxiety Scale for People with Intellectual Disability, was under development when these data were analysed and was not included in the analyses. Future work could test whether the same correlates emerge with that measure and determine whether the relationships can be used to identify anxiety risk or shape effective support.

The present results point to individual profiles involving sound processing, uncertainty, and physical health, while leaving their direction, mechanisms, and practical clinical utility unresolved.

Subject of Research: Cross-sectional analysis of anxiety correlates in children and adults with moderate to profound intellectual disability

Article Title: Correlates of Anxiety in Children and Adults With Moderate to Profound Intellectual Disability

Article References: Edwards, G., Tarver, J., Mingins, J. E., Oliver, C., Horton, I., & Waite, J. (2026). Correlates of Anxiety in Children and Adults With Moderate to Profound Intellectual Disability. Journal of Autism and Developmental Disorders. https://doi.org/10.1007/s10803-026-07539-2

Image Credits: AI Generated

DOI: 10.1007/s10803-026-07539-2

Keywords: intellectual disability, anxiety, auditory processing, intolerance of uncertainty, physical health, autism, genetic syndromes, parent reports, cross-sectional study, Correlates, Children, Adults