Enhanced disgust generalization in obsessive-compulsive disorder is related to insula and putamen hyperactivity

Abstract

Background: Compulsive cleaning is a characteristic symptom of a particular subtype of obsessive-compulsive disorder (OCD) and is often accompanied by intense disgust. While overgeneralization of threat is a key factor in the development of obsessive-compulsive symptoms, previous studies have primarily focused on fear generalization and have rarely examined disgust generalization. A systematic determination of the behavioral and neural mechanisms underlying disgust generalization in individuals with contamination concern is crucial for enhancing our understanding of OCD.

Method: In this study, we recruited 27 individuals with high contamination concerns and 30 individuals with low contamination concerns. Both groups performed a disgust generalization task while undergoing functional magnetic resonance imaging (fMRI).

Results: The results revealed that individuals with high contamination concern had higher disgust expectancy scores for the generalization stimulus GS4 (the stimulus most similar to CS+) and exhibited higher levels of activation in the left insula and left putamen. Moreover, the activation of the left insula and putamen were positively correlated with a questionnaire core of the ratings of disgust and also positively correlated with the expectancy rating of CS+ during the generalization stage.

Conclusion: Hyperactivation of the insula and putamen during disgust generalization neutrally mediates the higher degree of disgust generalization in subclinical OCD individuals. This study indicates that altered disgust generalization plays an important role in individuals with high contamination concerns and provides evidence of the neural mechanisms involved. These insights may serve as a basis for further exploration of the pathogenesis of OCD in the future.

Keywords: ROI; acquisition; conditioned responses; contamination concern; contamination-related fear; disgust; disgust learning; fMRI; generalization; insula; obsessive-complusive disorder; putamen.

Figure 1.

Experimental procedure diagram of acquisition phase and generalization phase. (a) In acquisition phase, subjects were required to score the likelihood of a disgusting stimulus following different stimuli. (b) In the generalization phase only a small probability of following the aversive pictures after CS+, subjects need to rate the generalized stimuli according to the laws learned in the acquisition phase.

Figure 2.

Behavioral results during the acquisition stage. (a) Acquisition phase rating scores for both groups of subjects. There were no between-group differences in the pattern of acquisition for both groups. (b) Disgust ratings to stimuli in both groups during the acquisition phase, subjects in the high compulsive tendency group had higher CS+ disgust ratings. Error bars reflect ± standard deviation (SD). ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001.

Figure 3.

Subjects’ expectancy ratings of different types of stimuli during the generalization phase. (a) Shows the ratings of the two groups of subjects for different stimulus types. (b) Demonstrates the difference in overall scores between the two groups of subjects across trials. Error bars reflect ± Standard deviation (SD).

Figure 4.

Activation of the left insula and Bilateral putamen. (a) Activation of left insula between two groups. (b) Activation of left putamen between two groups. (c) Activation of right putamen between two groups. Error bars reflect ± Standard deviation (SD). p < 0.05, p < 0.01, p < 0.001.