Remitted major depression is characterized by reward network hyperactivation during reward anticipation and hypoactivation during reward outcomes

Abstract

Background: Although functional brain imaging has established that individuals with unipolar major depressive disorder (MDD) are characterized by frontostriatal dysfunction during reward processing, no research to date has examined the chronometry of neural responses to rewards in euthymic individuals with a history of MDD.

Method: A monetary incentive delay task was used during fMRI scanning to assess neural responses in frontostriatal reward regions during reward anticipation and outcomes in 19 participants with remitted major depressive disorder (rMDD) and in 19 matched control participants.

Results: During the anticipation phase of the task, the rMDD group was characterized by relatively greater activation in bilateral anterior cingulate gyrus, in right midfrontal gyrus, and in the right cerebellum. During the outcome phase of the task, the rMDD group was characterized by relatively decreased activation in bilateral orbital frontal cortex, right frontal pole, left insular cortex, and left thalamus. Exploratory analyses indicated that activation within a right frontal pole cluster that differentiated groups during reward anticipation predicted the number of lifetime depressive episodes within the rMDD group.

Limitations: Replication with larger samples is needed.

Conclusions: Results suggest a double dissociation between reward network reactivity and temporal phase of the reward response in rMDD, such that rMDD is generally characterized by reward network hyperactivation during reward anticipation and reward network hypoactivation during reward outcomes. More broadly, these data suggest that aberrant frontostriatal response to rewards may potentially represent a trait marker for MDD, though future research is needed to evaluate the prospective utility of this functional neural endophenotype as a marker of MDD risk.

Conflict of interest statement

Conflict of Interest

All authors declare that they have no conflicts of interest.

Copyright © 2011 Elsevier B.V. All rights reserved.

Figures

Figure 1

The MID task. Each trial consisted of a cue (i.e., a triangle indicated an incentive trial, a circle indicated a non-incentive trial), an anticipatory delay, a target, and outcome feedback.

Figure 2

Clusters showing significant group differences during reward anticipation (z > 2.58, with a minimum of 10 voxels/cluster). Responses are masked by the responses of both groups combined thresholded by the same criteria.

Figure 3

Clusters showing significant group differences during reward outcomes (z > 2.58, with a minimum of 10 voxels/cluster). Responses are unmasked.

Figure 4

Left: Average reaction times to targets. Error bars reflect standard errors of the mean. Right: Significant relation between frontal pole activation during monetary anticipation and the number of lifetime MDD episodes in the rMDD group. The frontal pole cluster was defined on the basis of group difference in activation during this phase of the task.