A systematic review of intolerance of uncertainty in Hoarding Disorder, and an empirical study of the association between complex Post-Traumatic Stress Disorder and Hoarding Disorder

Dawson, Bronwen 2025. A systematic review of intolerance of uncertainty in Hoarding Disorder, and an empirical study of the association between complex Post-Traumatic Stress Disorder and Hoarding Disorder. ClinPsy Thesis, Cardiff University. Item availability restricted.

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Abstract

Hoarding Disorder (HD) is a debilitating mental health condition in which individuals experience significant difficulties in parting with their possessions, leading to clutter, such that it negatively impacts on their ability to use their living spaces in the home and their quality of life. Empirical evidence has also pointed to the prevalence of traumatic experience in the HD population, yet the pathway between trauma and HD is not well understood. HD has garnered growing research interest, however, the current evidence-based treatment for HD (namely Cognitive Behavioural Therapy) is modest, signalling the potential to further explore gaps in the current conceptualisation and treatment approach. The two studies presented in this thesis, ‘A Systematic Review of Intolerance of Uncertainty in Hoarding Disorder’ and ‘An Empirical Study of the Associations Between Complex Post-Traumatic Stress Disorder and Hoarding Disorder’ aims to bridge this gap by addressing the role of trauma in HD. Intolerance of uncertainty (IU) was initially developed to conceptualise generalised anxiety disorder; however, it is currently widely accepted as a transdiagnostic psychological construct associated with a range of mental health conditions. Research has also recognised IU as a possible factor of individual difference within the cognitive-behavioural model of HD. This systematic review aimed to investigate the relationship between IU and HD by addressing the strength and specificity of this relationship compared to other psychological vulnerability constructs and clinical groups. Across databases, a comprehensive search strategy was conducted, yielding 11 studies investigating the relationship between IU and HD in 3,018 participants. A narrative synthesis highlighted a strong and consistent association between IU and HD. However, the strength of this relationship was comparable to other psychological vulnerability constructs, and there was no evidence to support IU being specific to HD compared to other psychopathologies, but rather being amplified in comorbid groups with more complexity. Nevertheless, evidence collectively suggested the relationship between IU and HD to operate through unhelpful beliefs about possessions unique to HD. Although the results suggested IU to be a transdiagnostic process, findings are discussed in the context of IU as a vulnerability and maintenance factor of hoarding symptoms using Freeston and Komes’s (2023) somatic error theory. Given the pervasiveness of traumatic experience in the HD population, IU is also discussed in the context of trauma in HD by identifying common links between the somatic error theory and Hyland et al.’s (2023) memory and identity theory of complex post-traumatic stress disorder (CPTSD). Despite empirical reports of elevated experiences of adverse events and trauma sequelae in the HD population, the prevalence of PTSD is surprisingly low. The empirical study sought to understand this gap, emerging from identifying conceptual overlaps between the cognitive-behavioural model of HD and the Disturbances in Self Organisation (DSO) construct of CPTSD from the 11th version of the International Classification of Diseases (ICD-11), comprising affective dysregulation, negative self-concept, and disturbances in relationships. A cross-sectional, correlational study design was used with a single group of participants to test the association between CPTSD and HD through administering questionnaires on hoarding severity, childhood and lifetime trauma experience, affective dysregulation, negative self-concept, and disturbances in relationships. Results showed that the majority of participants reported experiencing childhood and lifetime adverse events and endorsed the ICD-11 PTSD or CPTSD criteria. Although there was no evidence to support a relationship between hoarding severity and disturbances in relationships, findings suggested affective dysregulation and negative self-concept to be related to hoarding symptoms, however, the exact nature of their interactions remained unclear. Findings also showed DSO symptoms to fully mediate the relationship between childhood, but not lifetime, adverse experience and hoarding severity. Whilst the cognitive-behavioural model of HD acknowledges traumatic exposure as a vulnerability factor, there is a gap in understanding its link to the manifestation of hoarding symptoms. Therefore, the findings are discussed under the framework of the memory and identity theory of CPTSD (Hyland et al., 2023) which offers a conceptually direct link between traumatic experiences as a vulnerability and maintenance factor in the cognitive-behavioural conceptualisation of HD. Overall, both studies contribute to the advancement of the cognitive-behavioural conceptualisation of HD; through exploring the role of trauma as a core vulnerability and maintenance factor of hoarding symptoms by drawing a conceptual link with Hyland et al.’s (2023) memory and identity theory of CPTSD. Recommendations to clinical practice is also suggested, such as the assessment of trauma in HD to aid an in-depth formulation to support clinicians in planning a holistic, trauma-informed treatment approach.

Item Type:	Thesis (DClinPsy)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Psychology
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Date of First Compliant Deposit:	15 December 2025
Last Modified:	15 Dec 2025 17:03
URI:	https://orca.cardiff.ac.uk/id/eprint/183250

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