Müller, Stefanie Verena; Morishima, Yosuke; Schwab, Simon; Wiest, Roland; Federspiel, Andrea; Hasler, Gregor (3 December 2017). Neural Correlates of Impaired Reward-Effort Integration in Remitted Bulimia Nervosa. Neuropsychopharmacology, 43, S149-S149. Nature Publishing Group
Background: The integration of reward magnitudes and effort costs is required for an effective behavioral guidance. This reward-effort integration was reported to be dependent on dopaminergic neurotransmission. As bulimia nervosa has been associated with a dysregulated dopamine system and catecholamine depletion led to reward processing deficits in remitted bulimia nervosa, the purpose of this study was to identify the role of dopamine dysfunction and its relation to behavioral and neural reward-effort integration in bulimia nervosa.
Methods: To investigate the interaction between catecholamine functioning and behavioral, and neural responses directly, 17 remitted bulimic (rBN) and 21 healthy individuals (HC) received alpha-methyl-paratyrosine (AMPT) over 24 hours to achieve catecholamine depletion in a randomized, crossover study design. We used functional magnetic resonance imaging (fMRI) with the Monetary Incentive Delay (MID) task to assess reward-effort integration in relation to dopaminergic neurotransmission at the behavioral and neural computational level.
Results: AMPT reduced the ability to integrate rewards and efforts effectively in HC participants. In contrast, in rBN participants, the reduced reward-effort integration was associated to illness duration in the sham condition and unrelated to catecholamine depletion. Regarding neural activation, AMPT decreased the reward prediction error signal in the anteroventral striatum. This decrease was associated with the AMPT-induced reduction of monetary earning in HC in contrast to rBN participants.
Conclusions: Our findings contributed to the theory of a desensitized dopaminergic system in bulimia nervosa. A disrupted processing of reward magnitudes and effort costs might increase the probability of maintenance of bulimic symptoms.
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