ABSTRACT
INTRODUCTION: Theory of mind (ToM) is important for social interactions and typical development and has been found to be impaired in patients with anorexia nervosa (AN) and bulimia nervosa (BN). Hypoactivation in frontotemporal brain regions seems to be the underlying neural mechanism in AN while whole-brain analyses in BN are lacking. METHODS: We used the well-validated social recognition task fMRI paradigm to assess ToM in a total of 72 female adolescents (16 BN, 18 AN and 38 matched healthy controls [HC]). RESULTS: Compared to HCBN , patients with BN showed hyperactivity during ToM-activity in the right frontal pole, middle temporal gyrus and left temporal pole and differed fundamentally from hypoactivation in these regions observed in patients with AN before and after short-term weight rehabilitation. Interaction and overlap analyses confirmed that similar regions were affected in opposite directions in both diseases. Hyperactivations in BN in the right middle temporal gyrus and right frontal pole were associated with clinical BN-severity markers binging and purging frequency. DISCUSSION: The hyperactivation in BN suggest different underlying neural mechanisms for ToM compared to AN. Hyperactivity might correspond to a different but also ineffective cognitive style in patients with BN when approaching social interactions. These important transdiagnostic differences are relevant for future brain-targeted therapeutic approaches.