Is disgust in obsessive-compulsive disorder mediated by fear of pathogens?

Individuals with obsessive-compulsive disorder (OCD) tend to report higher levels of disgust, but not much is known about factors that might underlie this relationship. The present study was motivated by the behavioral immune theory, which suggests that disgust has evolved as a protective reaction to potential presence of disease agents in the immediate environment. We examined the relationships between the intensity of experienced physical disgust, perceived vulnerability to disease, and OCD symptoms. The intensity of experienced disgust was assessed with a recent procedure whereby participants rate how disgusted they feel in response to color versus black-and-white pictures that evoke physical disgust. In addition to this procedure, participants (N = 403) completed measures of perceived vulnerability to disease, OCD symptoms, depression and anxiety. OCD symptoms were positively related to the physical disgust evoked by the pictures, and this relationship was mediated by reported emotional discomfort in contexts that connote a potential for pathogen transmission. Replicating previous findings, color pictures were rated as more disgusting than black-and-white pictures overall, and this effect was especially pronounced among people with higher OCD tendencies. These results suggest that, consistent with behavioral immune theory, disgust in OCD is a basic, concrete emotion that is at least partly mediated by fear of pathogens.