background Patients with obsessive compulsive disorder (ocd) have an increased neural response in ‘emotional’ brain areas to diseaserelevant stimuli. We hypothesise that this heightened response in ocd is due to a deficit in emotion regulation. We further hypothesise that this decreased cognitive control might be improved by repetitive transcranial magnetic stimulation (rtms) over the dorsal prefrontal cortex.
aim To assess the effect of stimulatory rtms over dorsal prefrontal cortex on emotion processing and emotion regulation in ocd patients.
method Thirty ocd patients and 30 matched controls performed an emotion regulation task. Subjects performed this task on two occasions: the first time as a baseline measurement without rtms, and a second time after the application of real or placebo rtms over dorsal prefrontal cortex. The effects of rtms will be assessed on both the behavioural distress scores and neural activation.
results Firstly, ocd patients rated the fear and ocd stimuli as being significantly more distressful than the neutral stimuli, and more so than controls. Secondly, in both groups regulating decreased the distress ratings in comparison to the ‘attend’ condition. Within group effects of ‘regulate’as compared to ‘attend’, however, showed a significant BOLD activation in right dorsolateral pfc in controls, which was absent in patients. Patients, on the other hand, showed a group-specific activation in the left dorsal premotor area during regulation.
conclusion The observed increased distress ratings and heightened amygdala reflects successful symptom provocation in our paradigm. The differential recruitment of frontal areas in ocd as compared to controls during emotion regulation (i.e. dorsal premotor and dorsolateral pfc activation, respectively) seems to be in line with our hypothesis of dorsal prefrontal dysfunction in ocd.