Abstract
Antidepressants remediate negative biases in emotional processing early in treatment, prior to mood improvement. However, the effects on reward processing potentially relevant to the treatment of anhedonia are less clear. Here we investigate the early and sustained effects of the dopamine and noradrenaline reuptake inhibitor bupropion on behavioural measures of emotional and reward processing in currently depressed individuals. Forty-six currently depressed patients and 42 healthy controls participated in a repeated measures study, during which open-label bupropion was administered to only the patient group over a six week period without a placebo group. All participants completed the Emotional Test Battery and a probabilistic instrumental learning task at week 0, week 2 and week 6. Currently depressed patients displayed negative biases in emotional processing and blunted response bias for high-probability wins compared to the healthy controls at baseline. Bupropion was found to reduce the negative biases in emotional processing early in treatment, including a significant decrease in the percentage misclassification of other face emotions as sad and the number of negative self-referent words falsely recalled between baseline and week 2. Conversely, bupropion was found to initially further reduce the response bias for high-probability wins between baseline and week 2. This effect reversed with six weeks' bupropion treatment and reward processing was normalized compared to the healthy controls. Early in treatment, bupropion acts to reduce negative biases in emotional processing but exacerbates impaired reward processing. The beneficial actions of bupropion on reward processing then occur later in treatment. Such dissociation in the temporal effects of bupropion on emotional and reward processing has implications for the treatment of the different symptom domains of negative affect and anhedonia in depression.This article is part of a discussion meeting issue 'Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'.
Highlights
Cognitive theories of depression suggest that negative biases in emotional processing play an important role in the causation and maintenance of the persistent low mood characteristic of the disorder
7 day treatment or even an acute dose of the selective serotonin reuptake inhibitor (SSRI) citalopram or the noradrenaline reuptake inhibitor reboxetine was found to increase the perception of ambiguous faces as happy and the recall of positive self-referent words in both healthy volunteers [14 –16] and depressed patients [17] compared to placebo
There were no significant differences between the major depressive disorder (MDD) and healthy controls (HCs) groups with regards to gender, age or national adult reading test (NART)-derived verbal IQ
Summary
Cognitive theories of depression suggest that negative biases in emotional processing play an important role in the causation and maintenance of the persistent low mood characteristic of the disorder. 7 day treatment or even an acute dose of the selective serotonin reuptake inhibitor (SSRI) citalopram or the noradrenaline reuptake inhibitor reboxetine was found to increase the perception of ambiguous faces as happy and the recall of positive self-referent words in both healthy volunteers [14 –16] and depressed patients [17] compared to placebo. These changes in emotional processing biases occurred in the absence of changes in subjective mood, suggesting that they may be a direct effect of antidepressant drug treatment rather than being a secondary consequence of changes in mood and affect
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
