BACKGROUND: Overestimation of threat (OET) is ascribed a pathogenetic role in obsessive-compulsive disorder (OCD). AIMS: We hypothesized that OCD patients overestimate their personal but not the average risk for OCD-related events. Specifically, an attenuation of the common "unrealistic optimism" bias (UO) was expected for OCD patients. UO refers to the phenomenon that the subjective likelihood to personally experience a positive event is enhanced compared to other persons and vice versa for negative events. METHOD: Fifty-three participants with OCD as well as 40 healthy and 23 psychiatric controls participated in an internet survey. They were asked several questions about different event types (positive, negative, and OCD-related): the probability that this event will happen to oneself (block 1), to another person (block 2), comparison between oneself versus another person (block 3), appraisal of consequences (block 4), and prior encounters with event (block 5). RESULTS: No evidence was obtained in OCD to overestimate the overall probability of negative or OCD-related events. However, whereas healthy participants displayed an UO bias, OCD participants perceived themselves as more vulnerable to experience OCD-related events. CONCLUSIONS: Results indicate that OCD is associated with inflated personal vulnerability and that this bias is not fully available to the consciousness of OCD participants.
