Disgust and Other Negative Emotions in the Relationship between Mental Contamination and Post-Traumatic Stress Disorder: A Systematic Review.

Background: Mental contamination (MC) refers to feelings of internal filthiness associated with contamination obsessions. Ego-dystonic memories and thoughts can trigger MC, although it can also be activated by trauma, which is associated with the onset of post-traumatic stress disorder (PTSD). Research shows that MC, negative emotions and PTSD can occur simultaneously. Despite considerable interest from researchers and clinicians, to the best of our knowledge, no systematic review has been carried out on the relationship between disgust and other negative emotions with MC and PTSD. Therefore, we conducted this systematic review to summarise and synthesise the current understanding of these constructs in PTSD. The main objective of this study was to review the association between MC, post-traumatic stress disorder and trauma; the role of disgust and other negative emotions in these associations; and whether the relationship between MC and trauma is limited to traumatic sexual experiences.

Method: We searched PsycINFO, Psychology and Behavioural Sciences Collection, Scopus, Web of Science, Medline, PubMed, ProQuest Dissertations and Theses, Cochrane Library, APA PsycNet, and the Online Library of the University of Algarve. We also included grey literature published in Google Scholar. The Mixed Methods Appraisal Tool was used to assess the methodological quality of the included studies.

Results: Twenty studies met the inclusion criteria for the review. Among these, six studies used a randomised methodology, nine used a non-randomised methodology, and five used a descriptive methodology. The results showed that MC is associated with all types of interpersonal trauma, although the relationship with sexual trauma was the strongest. Both basic emotion and disgust sensitivity appear to be significantly associated with MC and the severity of PTSD symptoms. Similarly, other negative emotions are positively associated with MC, although the experience and reappraisal of negative emotions may potentially attenuate the experience of MC.

Conclusions: Based on the findings, MC, disgust and negative emotions are important clinical constructs associated with trauma and PTSD. These results may contribute to our understanding and treatment of PTSD.