Many compulsions displayed by obsessive-compulsive disorder (OCD) patients serve to protect against perceived threat and can, therefore, be conceptualized as 'avoidance responses'. Exposure treatment with response prevention (ET+RP) is aimed at exposing patients to their obsessive thoughts and perceived threats while preventing engagement in compulsive avoidant responses. This induces extinction of threat perception and fearful arousal and hence reduces the motivation to avoid. While successful in many patients, however, as much as 40% dropout during treatment or display persistent avoidance after ET+RP. There is a clear need for treatment improvement for these often highly disabled patients.~Improving ET+RP outcomes requires a deeper understanding of the mechanisms that drive excessive and persistent avoidance in OCD patients. Psychological theories ascribe an important role to the relief that follows avoidance when the anticipated threat is successfully averted. This positive feeling arguably functions as a reward to reinforce the foregoing avoidance actions. Indeed, fMRI studies have found that the neurocircuitry of relief overlaps with that of reward, including the ventral tegmental area, ventral striatum and orbitofrontal cortex. Here, the authors will test the hypothesis that excessive-persistent avoidance is linked to exaggerated activation of the relief circuitry in OCD patients. For that purpose, we will acquire functional brain images of OCD patients in an MRI scanner and compare to healthy participants, while they participate in a computer task that is designed to model avoidance learning and relief.
To investigate the neuro-mechanisms underpinning persistent avoidance in OCD patients