Abnormal Social Reward Responses in Anorexia Nervosa : An fMRI Study

Abstract

Altres ajuts: This study was supported in part by the Carlos III Health Institute (ISCIII, PI08/1549, PI11/210 and PI14/290) and by Fondos Europeos de Desarrollo Regional (FEDER). CIBERobn and CIBERSAM are both initiatives of ISCIII.). Dr. Soriano-Mas is funded by a 'Miguel Servet' contract from the Carlos III Health Institute (I.D. CP10/00604). A/Prof. Harrison is supported by a National Health and Medical Research Council of Australia (NHMRC) Clinical Career Development Fellowship (I.D. 628509). Dr. Davey is supported by a NHMRC Clinical Career Development Fellowship (I.D. 1061757). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

Patients with anorexia nervosa (AN) display impaired social interactions, implicated in the development and prognosis of the disorder. Importantly, social behavior is modulated by reward-based processes, and dysfunctional at-brain-level reward responses have been involved in AN neurobiological models. However, no prior evidence exists of whether these neural alterations would be equally present in social contexts. In this study, we conducted a cross-sectional social-judgment functional magnetic resonance imaging (fMRI) study of 20 restrictive-subtype AN patients and 20 matched healthy controls. Brain activity during acceptance and rejection was investigated and correlated with severity measures (Eating Disorder Inventory -EDI-2) and with personality traits of interest known to modulate social behavior (The Sensitivity to Punishment and Sensitivity to Reward Questionnaire). Patients showed hypoactivation of the dorsomedial prefrontal cortex (DMPFC) during social acceptance and hyperactivation of visual areas during social rejection. Ventral striatum activation during rejection was positively correlated in patients with clinical severity scores. During acceptance, activation of the frontal opercula-anterior insula and dorsomedial/dorsolateral prefrontal cortices was differentially associated with reward sensitivity between groups. These results suggest an abnormal motivational drive for social stimuli, and involve overlapping social cognition and reward systems leading to a disruption of adaptive responses in the processing of social reward. The specific association of reward-related regions with clinical and psychometric measures suggests the putative involvement of reward structures in the maintenance of pathological behaviors in AN.