A Dissociation of the Acute Effects of Bupropion on Positive Emotional Processing and Reward Processing in Healthy Volunteers

Abstract

Background: Previous research indicates that antidepressants can restore the balance between negative and positive emotional processing early in treatment, indicating a role of this effect in later mood improvement. However, less is known about the effect of antidepressants on reward processing despite the potential relevance to the treatment of anhedonia. In this study, we investigated the effects of an acute dose of the atypical antidepressant (dual dopamine and noradrenaline reuptake inhibitor) bupropion on behavioral measures of emotional and reward processing in healthy volunteers. Methods: Forty healthy participants were randomly allocated to double-blind intervention with either an acute dose of bupropion or placebo prior to performing the Emotional Test Battery (ETB) and a probabilistic instrumental learning task. Results: Acute bupropion significantly increased the recognition of ambiguous faces as happy, decreased response bias toward sad faces and reduced attentional vigilance for fearful faces compared to placebo. Bupropion also reduced negative bias compared to placebo in the emotional recognition memory task (EMEM). There was no evidence that bupropion enhanced reward processing or learning. Instead, bupropion was associated with reduced likelihood to choose high-probability wins and increased score on a subjective measure of anhedonia. Conclusions: Whilst acute bupropion decreases negative and increases positive emotional processing, it has an adverse effect on reward processing. There seems to be a dissociation of the acute effects of bupropion on positive emotional processing and reward processing, which may have clinical implications for anhedonia early in treatment.

Keywords: anhedonia; antidepressants; depression; dopamine; emotion; reward.

Figure 1

FERT (A) % accuracy for each happiness intensity and signal detection derived (B) d' and (C) beta for happy and sad faces for each treatment group. Values are reported as means ± SEM. Asterisks denote the degree of significance obtained for planned comparisons (*p < 0.05, **p < 0.01).

Figure 2

FDOT attentional vigilance for each masking and face emotion condition for each treatment group. Values are reported as means ± SEM. Asterisks denote the degree of significance obtained for planned comparisons (*p < 0.05).

Figure 3

EMEM (A) % misclassification and (B) beta for each word valence and treatment group. Values are reported as means ± SEM. Asterisks denote the degree of significance obtained for planned comparisons (*p < 0.05).

Figure 4

(A) End total, amount won and amount lost and (B) reaction time for the win and loss conditions of the probabilistic instrumental learning task for each treatment group. Values are reported as means ± SEM.

Figure 5

(A) Learning curves for each treatment group depicting trial-by-trial the proportion of participants that chose the correct symbol in the win condition, associated with high-probability win (top lines) and the incorrect symbol in the loss condition, associated with high-probability loss (bottom lines) during the probabilistic instrumental learning task. (B) Proportion of participants choosing the correct symbol in the win and loss conditions averaged over the last 20 trials of the probabilistic instrumental learning task where learning had plateaued. Asterisks denote the degree of significance obtained for planned comparisons (**p < 0.01).