Rapid habituation of ventral striatal response to reward receipt in postpartum depression

Abstract

Background: Little is known about neural mechanisms of postpartum depression (PPD). Previous research notes ventral striatal activity and dopamine release increases with maternal attachment but decreases in major depressive disorder. This study tests the hypothesis that striatal response to reward is altered in PPD.

Methods: Subjects underwent functional magnetic resonance imaging blood oxygenation level-dependent acquisition during a fast event-related card-guessing, monetary reward task. Time series data from an independent sample of 10 healthy mothers were used to establish the ventral striatal region of interest (ROI). Repeated-measures analysis of variance of time series data in the established ROI was then conducted for a discrete group of healthy (n = 12) and depressed, unmedicated mothers (n = 12).

Results: Data from the independent sample of 10 healthy mothers established an ROI in the left ventral striatum (-13, 12, -4, 477 mm(3)), with cluster significance p < .01, corrected. There was a significant quadratic interaction of time × group [F(1,22) = 5.22, p = .032] in this ROI in the healthy (n = 12) and depressed mothers (n = 12). This effect represents a nonlinear attenuation of ventral striatal response with time that was greater in depressed than healthy mothers.

Conclusions: Rapid attenuation of ventral striatal response to reward receipt in postpartum depression might represent an important neural mechanism of postpartum depression. Additional study with infant stimuli and in relationship to mother-infant behavior is needed.

Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

A. Left ventral striatal region of interest [Talairach coordiantes for center voxel −13, 12, −4, volume 477 mm3] established through the Reward minus Punishment contrast in the independent sample of 10 healthy mothers. B. Time course data for healthy (n=12) and depressed (n=12) mothers during high reward trials, extracted from the left ventral striatum regions of interest (figure A). Left ventral striatal BOLD activity associated with rewarding feedback increased in both depressed and healthy mothers from TR 1 to TR 4–5; however, the depressed mothers showed a more rapid attenuation of left ventral striatal response. Errors bars show standard error of the mean. C. Time course data for depressed mothers averaged from TR 1 through 11 is shown relative to depressive severity, measured with the self-report Edinburgh postnatal scale for depression (Spearman rho = −0.80; p=0.002).