Disrupted posterior cingulate-amygdala connectivity in postpartum depressed women as measured with resting BOLD fMRI

Abstract

Disengagement of emotion regulation circuits was previously shown in depressed mothers and was hypothesized to underlie the impaired maternal-infant sensitivity described in postpartum depression (PPD). We hypothesized similarly reduced resting-state functional connectivity in default mode network (DMN) regions involved in social cognition in PPD. Resting-state functional MRI, clinical and mother-infant attachment data were obtained from 14 unmedicated postpartum women with major depression and 23 healthy postpartum women. Posterior cingulate cortex (PCC) time series were extracted, filtered between 0.007 and 0.08 Hz and used as regressors in a whole brain general linear model analysis. PCC-right amygdala connectivity was significantly disrupted in depressed compared to healthy mothers for low-frequency neural activity, showing a negative (inverse) coupling in the depressed group but not in the controls. PCC-right amygdala connectivity was positively correlated with PCC-parahippocampus connectivity. Resting connectivity patterns of positive co-activations in postpartum women mirrored the canonical DMN. These findings of reduced PCC-amygdala coupling raise the possibility that PPD might involve the disruption of outward, preventative aspects of self-relevant thought and theory of mind/empathy processes. Further integrated studies of neural connectivity and these cognitive/behavioral dimensions are warranted.

Keywords: default mode network; fMRI; posterior cingulate cortex; postpartum depression.

Fig. 1

Statistical map of PCC/whole-brain functional connectivity at low frequencies (0.007–0.08 Hz) across all subjects (n = 37: threshold set at uncorrected P < 0.001). Regions in red represent areas that are positively coupled and blue regions represent areas that are negatively coupled with PCC time series. The scale at the top right represents the color coding of the range of t-statistics.

Fig. 2

Figure describing the right amygdala region which displayed reduced PCC–amygdala connectivity in depressed compared with healthy mothers (peak voxel: 33 5 −20; T = 5.45, P = 0.043, FWE corrected). The region (displayed at a threshold of P < 0.001, uncorrected) overlapped with the right basolateral and superficial nuclei of the amygdala. Parameter estimates of the PCC connectivity within the significant region displayed on the right hand side (error bars reflect standard error of the mean).

Fig. 3

Figure representing most prominent regions of PCC connectivity within a mask constrained to amygdala–whole-brain connectivity (P < 0.001, uncorrected). This included the bilateral parahippocampal gyrus/subiculum (21 −19 −20; −24 −19 −23) and a region of pregenual ACC (6 26 10). There were no significant between-group differences in PCC connectivity within these regions.

Fig. 4

Association of PCC–right amygdala connectivity with PCC–parahippocampal and PCC–pregenualACC connectivity: PCC–right amygdala coupling correlated positively and significantly with PCC–right parahippocampus/subiculum coupling (black squares) but not PCC–pgACC coupling (open circles).