The current status of mental contamination in obsessive compulsive disorder: A systematic review

Over the past 25 years Mental Contamination (MC) has become recognised as a distinct construct, particularly in relation to Obsessive Compulsive Disorder (OCD). MC is defined as feelings of contamination, often located internally, that arise in the absence of contact with a contaminant, with the source proposed to be human. Despite considerable interest from researchers and clinicians, there has not been a systematic review on the relationship between MC and OCD. Therefore, a systematic review was conducted to summarise and synthesise the current status of phenomenological and experimental evidence, mechanisms, assessment, measurement, and treatment of MC in OCD (PROSPERO: CRD42021223119).

All study designs were eligible provided the focus of the study was on MC and the implications of the study were linked to OCD. We searched PsychINFO, Embase, Medline, Ethos, ProQuest, conference abstracts and trial registries between 1990 and 2021. The Mixed Methods Appraisal tool was used to assess methodological quality of included studies.

We found 58 reports with a total of 67 studies that met criteria for inclusion in the review. Twenty-three of these studies used clinical samples, 28 were experimental, 12 focused on phenomenology and 8 addressed treatment. The quality of the studies was variable.

Grey literature was not included, thus there may be further unpublished MC studies that have not been included in the review.

Based on the findings, mental contamination is a robust clinical construct within OCD that has important implications for understanding and treating the disorder.