This study will investigate the role of dopaminergic neural systems in the symptoms and
treatment of depression. 40 patients who meet DSM-IV criteria for a diagnosis of depression
will be compared to a matched sample of healthy controls. The depressed group will receive
open label treatment with Bupropion MR (150mg bd) for 6 weeks. The control group will receive
no treatment. All participants will be assessed before treatment, after 2 weeks treatment and
at 6 weeks treatment. The outcomes assessed will be 1) fMRI estimates of neural response to
reward to emotionally valenced stimuli (1st and 2nd assessments), 2) computer based measures
of emotional processing (all assessments) and 3) standardised questionnaire measures of
depressive symptoms (all assessments). The primary study hypothesis is that altering central
dopamine using Bupropion will lead to altered neural responses to rewarding stimuli in the
depressed patients (i.e. comparing fMRI outcomes between assessment visits 1 and 2). A
secondary hypothesis is that this neural change will predict subsequent symptom response to
the bupropion (i.e. comparing symptom scores between assessment visits 1 and 3), Lastly, the
study will test the hypothesis that baseline differences in reward circuitry will be
particularly associated with symptoms of anhedonia (the inability to experience pleasure).