Reward Processing and Inhibitory Control in Women with Bulimia Nervosa

Abstract

Introduction: Theoretical models and empirical research support the role of negative affect in bulimia nervosa (BN). However, treatments that target negative affect in BN have not outperformed traditional, eating-disorder-focused treatments for BN. An alternative mechanism of BN is dysfunctional positive affect (i.e., reward processing). The present study aimed to understand associations among dysfunctional reward processing, affect, and eating-disorder symptom expression by testing an interactive model of reward-based processes (reward learning, effort valuation, delay discounting, inhibitory control) in women with BN. Method: Participants were community-recruited medication-free adult women aged 18-30 with BN (n=20) or healthy controls (HCs; n=20). Behavioral tasks and self-report measures were used to assess reward learning, effort valuation, delay discounting, inhibitory control, BN symptom frequencies, and affect. Results: Women with BN did not differ from HCs on effort valuation and inhibitory control; however, women with BN showed less delay discounting and demonstrated slower reward learning compared to HCs. Frequency of fasting and excessive exercise episodes increased as inhibitory control decreased. Slowed reward learning was associated with increased self-induced vomiting frequencies in BN. Conclusions: Results suggested a modified model of reward dysfunction in BN, with delay discounting, reward learning, and negative urgency as central features. Given the associations of reward learning, delay discounting, and negative urgency, clinicians working with persons with BN may introduce strategies, such as pleasant activity scheduling, as a means to promote positive affect, regulate negative affect, and potentially decrease symptom expression in BN