Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Psychology, Clinical-Community

Date of Defense

5-14-2026

Graduate Advisor

Steven Bruce

Committee

Michael Griffin

Gregory Sayuk

Kamila White

Abstract

Current bodies of knowledge support the relationships between posttraumatic stress disorder (PTSD) and irritable bowel syndrome (IBS), pain catastrophizing and PTSD, and pain catastrophizing and IBS. However, much less is known regarding how pain catastrophizing influences the relationship between PTSD and IBS. Additionally, while correlations between some demographic and trauma-related symptomatology have been elucidated in the relationship between PTSD and IBS, their impact as potential moderators on the relationship between PTSD and IBS has yet to be fully examined. Examining a student sample from a large midwestern university, the present study aimed to investigate the potential mediating and moderating roles of several factors in the relationship between PTSD and IBS. For the full sample, pain catastrophizing scores were lower in participants without a trauma history versus participants with a trauma history and pain catastrophizing mediated the relationship between posttraumatic stress symptom severity and irritable bowel symptom frequency. However, pain catastrophizing did not mediate the relationship between posttraumatic stress symptom severity and IBS nor the relationship between posttraumatic stress symptom severity and probable IBS. Regarding potential moderators in the relationship between posttraumatic stress symptom severity and IBS status, probable IBS was not associated with White race, female gender, or increased number of unique trauma types. Future studies should examine other potential factors that may explain these findings (e.g., socioeconomic status, predisposing factors, temporal relationship between trauma and IBS, and other gastrointestinal conditions.

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