A positive behaviour support approach enhanced with cognitive behaviour therapy elements to improve anxiety related behaviour within family routines for autistic children with an intellectual disability

Abstract

Children on the Autism Spectrum are reported to experience anxiety with approximately 39.6% of those diagnosed receiving a diagnosis. An assessment of anxiety requires the ability for one to self-report anxiety symptomology. A core diagnostic feature of Autism Spectrum Disorder (ASD) is deficits in social communication, which may in turn create barriers to assessment and treatment of anxiety for autistic children. The additional diagnoses of a comorbid Intellectual Disability (ID) may further magnify these communication deficits further challenging both assessment and treatment approaches. Strategies grounded in the routes of Cognitive Behaviour Therapy (CBT) have been considered a gold standard treatment for anxiety with effects being demonstrated amongst the autistic population without an ID (Kester & Lucyshyn, 2018). Researchers in the field of Positive Behaviour Support (PBS) have focused on supporting individuals and key stakeholders in understanding and supporting behaviours that challenge (Brown et al., 2015; Clarke et al., 1999). There is emerging research supporting the use of a blended FCPBS and CBT approach for the treatment of anxiety amongst this population (Moskowitz et al., 2017). The aim of this thesis was to further evaluate this blended approach amongst the autistic population with comorbid ID. Firstly, a systematic review was conducted that aimed to replicate the work of Johnco & Storch (2015), identifying treatment implications for anxiety and then extending these findings to children with an ID. The review answered the following research questions: (a) What are the intervention characteristics included in the treatment of anxiety for children with ASD and ID? (b) Is CBT effective in the treatment of anxiety in children with ASD that fall below borderline/ average IQ (i.e., less than a score of 75) and (c) can CBT be enhanced by embedding ABA/PBS strategies in the treatment of anxiety in children with ASD and ID? The systematic review identified gaps in the literature for both the assessment and treatment of anxiety amongst the autistic population with comorbid ID. The identified gaps in the literature then led to the development of the applied study. The applied study focused on implementing a blended Family Centered Positive Behaviour Support (FCPBS) approach enhanced with CBT components within the naturalistic setting of a valued family routine for four families. A Non-concurrent Multiple Baseline Design (NCMBD) was used to demonstrate a functional relation between the FCPBS enhanced with CBT approach and an increase in steps achieved within each child’s respective anxiety hierarchy, an increase in positive engagement and a reduction in problem behaviour. Additionally, social validity measures were collected to evaluate parents’ perspectives on the acceptability and feasibility of the intervention. The results of the applied study led further to the development of the manual presented within this thesis ‘Redefining Routines - Overcoming Anxiety’ as a working framework for multidisciplinary teams supporting autistic children with an ID who are engaging in anxiety related behaviour.

Thesis is embargoed until 31 July 2026.

Date of Award	Jul 2025
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Paul Best (Supervisor) & Nichola Booth (Supervisor)