Blunted reward processing in remitted melancholic depression

Abstract

Blunted reward response appears to be a trait-like marker of vulnerability for Major Depressive Disorder (MDD). As such, it should be present in remitted individuals; however, depression is a heterogeneous syndrome. Reward-related impairments may be more pronounced in individuals with melancholic depression. The present study examined neural responses to rewards in remitted melancholic depression (rMD; N = 29), remitted non-melancholic depression (rNMD; N = 56), and healthy controls (HC; N = 81). Event-related potentials to monetary gain and loss were recorded during a simple gambling paradigm. rMD was characterized by a blunted response to rewards relative to both the HC and the rNMD groups, who did not differ from one another. Moreover, the rMD and rNMD groups did not differ in course or severity of their past illnesses, or current depressive symptoms or functioning. Results suggest that blunted response to rewards may be a viable vulnerability marker for melancholic depression.

Keywords: depression; melancholia; reward processing; vulnerability.

Figure 1

Stimulus-locked ERP waveforms at an average of electrode sites Cz and FCz for Healthy Controls (HC), remitted Non-Melancholic Depressed (rNMD), and Melancholic Depressed (rMD) groups. For each panel, stimulus onset occurred at 0 ms. Per ERP convention, negative voltages are plotted up.

Figure 2

Scalp topographies representing the RewP. These maps are derived from the average difference between conditions (non-reward minus reward response) from 220 to 360 ms and represent the Δ RewP for Healthy Controls (HC), Non-Melancholic Depressed (rNMD), and Melancholic Depressed (rMD) groups.