Amygdala responses to human faces in obsessive-compulsive disorder

Background To assess the amygdala response to emotional faces in obsessive-compulsive disorder (OCD) using functional magnetic resonance imaging (fMRI). Methods Ten subjects with current OCD and 10 healthy control subjects underwent fMRI, during which they viewed pictures of fearful, happy, and neutral human faces, as well as a fixation cross. Results Across both groups, there was significant activation in left and right amygdala for the fearful versus neutral faces contrast. Data extracted from these functionally defined regions of interest indicated that OCD subjects exhibited a weaker response than control subjects bilaterally across all face conditions versus fixation. No group-by-face condition interactions were observed. Conclusions Contrary to findings in other anxiety disorders, there was no observed increase in amygdala responsivity to fearful versus neutral human faces in OCD as compared with healthy control subjects. Moreover, across all face conditions, amygdala responsivity was attenuated in OCD subjects relative to control subjects. Therefore, the present findings are consistent with abnormal amygdala function in OCD and are of a character that may distinguish OCD from other anxiety disorders.