Reward Systems and Food Avoidance in Eating Disorders

Overview

The researchers plan to explore brain networks involved in emotion processing and learning using a brain scan and test meals. One core feature of Anorexia Nervosa (AN) is eating a small number of high-calorie or high-fat foods. By studying why individuals with AN are disgusted by food or other eating situations, the researchers will be able to understand more about the neurobiological pathways that lead to restricting food intake and food avoidance. This study also aims to find whether one of two short-term interventions (Interoceptive Exposure (IE); Family-Based Therapy (FBT)) affects connections in the brain and if the treatments affect food avoidance. IE is an intervention that helps reduce anxiety about eating. FBT is an intervention that motivates patients to eat through working with family to increase the value of eating and decrease the value of avoiding foods.

Anorexia nervosa (AN), a characteristically relentless pursuit of thinness with an intense fear of weight gain despite significantly low body weight, is a serious psychiatric disorder with high rates of morbidity and mortality. Low weight eating disorders (LW-ED), the broader category of eating pathology that includes AN and similar variants, are characterized by a chronic course, poor response to treatment, and food avoidance. Emerging neuroimaging evidence suggests that deficits in insula-amygdala-ventral striatum (IAVS) neurocircuitry contribute to individual variability in aversive and reward learning, and that these brain regions demonstrate abnormal responses to food/eating stimuli. The researchers' pilot data suggest that patients with LW-ED experience difficulty extinguishing food-cue associations in a reversal learning paradigm compared to healthy controls, a difficulty that is related to psychophysiological measures of aversive disgust (not fear). The researchers have also successfully piloted an interoceptive exposure intervention for this population that targets visceral sensitivity and seeks to increase 'top-down' regulation of the IAVS neurocircuit. The proposed project will (a) use novel fMRI-EMG to test the relationship between effective connectivity within amygdala-insula-ventral striatum network and its relationship to psychophysiological and behavioral measures of acute threat and reward learning in 60 adolescents with LWEDs and 30 healthy controls, (b) test the sensitivity of this network to an experimental interoceptive exposure paradigm relative to patients receiving family based therapy for weight restoration using dynamic causal modeling of fMRI-EMG data pre-post experimental conditions, (c) validate this model against objective measures of laboratory and real world eating behavior. The results of this study will help better understand the core neurocircuitry that underlies both threat processing and reward/aversive learning and how this circuit relates to objective behavior. Further, the researchers will determine the modifiability of this neurocircuitry via two distinct behavioral interventions chosen to target different aspects of affective processing and reward learning. These data will be used to inform future clinical interventions targeting aversive/reward learning within this population and dysregulation in insula-amygdala-ventral striatum subcircuits.