Subjective imagery in obsessive-compulsive disorder before and after exposure therapy. Pilot randomised controlled trial.

BACKGROUND: Distressing mental imagery is hard to study experimentally in obsessive--compulsive disorder (OCD). AIMS: To develop a way to assess mental imagery in OCD during functional magnetic resonance imaging (fMRI). METHOD: A small randomised study, controlled for type and order of mental imagery and for treatment condition (exposure therapy guided by a computer or by a therapist, or relaxation guided by audio-tape). Before and after treatment, during fMRI scanning, patients imagined previously-rehearsed scenarios that evoked an urge to ritualise or non-OCD anxiety or a neutral state, and rated their discomfort during imagery. RESULTS: The method evoked greater discomfort during OCD imagery and anxiety (non-OCD) imagery than during neutral imagery. Discomfort was reduced by cancelling imagery. Discomfort during OCD imagery (but not during anxiety non-OCD imagery) fell after exposure therapy but not after relaxation. CONCLUSIONS: Results showed differences between OCD and non-OCD images and their change after successful treatment, and confirmed clinical suggestions that cancelling images reduced OCD discomfort. The method's success paves the way for further studies of mental imagery in OCD: for instance, during fMRI.

A differential neural response in obsessive-compulsive disorder patients with washing compared with checking symptoms to disgust.

BACKGROUND: Patients with obsessive-compulsive disorder (OCD) have symptoms that predominantly concern washing (washers) or checking (checkers), or both. Functional neuroimaging has been used to identify the neural correlates of the urge to ritualize but has not distinguished between washing and checking symptoms in OCD. We used functional magnetic resonance imaging to compare the neural response to emotive pictures in washers and checkers. METHODS: In one of two 5-minute experiments, washers (N = 7), checkers (N = 7) and age-matched normal controls (N = 14) were scanned while viewing alternating blocks of normally disgusting (rated as disgusting by all subjects) and neutral pictures. In the other experiment, all patients and a normal subgroup (N = 8) viewed alternating blocks of washer-relevant (rated as more disgusting by washers than normal controls or checkers) and neutral pictures. RESULTS: In all subjects, normally disgusting pictures activated visual regions implicated in perception of aversive stimuli and the insula, important in disgust perception. Only in washers were similar regions activated by washer-relevant pictures. In checkers, these pictures activated fronto-striatal regions associated with the urge to ritualize in OCD. Normal controls were more similar in neural response to checkers than washers to these pictures. Both normal controls and checkers had frontal regions activated significantly more by washer-relevant than normally disgusting pictures, and had these regions activated significantly more than washers by washer-relevant pictures. CONCLUSIONS: We demonstrate a differential neural response to washer-relevant disgust in washers and checkers: only washers demonstrate a neural response to washer-relevant disgust associated with emotion perception rather than attention to non-emotive visual detail.