Disrupted prefrontal activity during emotion processing in complicated grief: An fMRI investigation

Abstract

Complicated Grief, marked by a persistent and intrusive grief lasting beyond the expected period of adaptation, is associated with a relative inability to disengage from idiographic loss-relevant stimuli (O'Connor and Arizmendi, 2014). In other populations, functional magnetic resonance imaging (fMRI) studies investigating the neural networks associated with this bias consistently implicate the anterior cingulate cortex (ACC) during emotion regulation. In the present study, twenty-eight older adults were categorized into three groups based on grief severity: Complicated Grief (n=8), Non-Complicated Grief (n=9), and Nonbereaved, married controls (n=11). Using a block design, all participants completed 8 blocks (20 stimuli per block) of the ecStroop task during fMRI data acquisition. Differences in neural activity during grief-related (as opposed to neutral) stimuli across groups were examined. Those with Complicated Grief showed an absence of increased rostral ACC (rACC) and fronto-cortical recruitment relative to Nonbereaved controls. Activity in the orbitofrontal cortex (x=6, y=54, z=-10) was significantly elevated in the Non-Complicated Grief group when compared to Nonbereaved controls. Post hoc analysis evidenced activity in the dorsal ACC in the Complicated Grief and Nonbereaved groups late in the task. These findings, supported by behavioral data, suggest a relative inability to recruit the regions necessary for successful completion of this emotional task in those with Complicated Grief. This deficit was not observed in recruitment of the orbitofrontal cortex and the rACC during processing of idiographic semantic stimuli in Non-Complicated Grief.

Keywords: Attention; Complicated Grief; Grief; Magnetic resonance imaging; Psychopathology; ecStroop.

Figure 1

Emotional Counting Stroop Task Design. Participants viewed four blocks of neutral words alternating with four block of grief-related words. Each block consisted of the same words presented in different order. Participants were told to ignore the semantic content of the word and respond with the number of words presented, as quickly and as accurately as possible The task began and ended with a fixation-point block, which consisted of a “+” sign presented in the center of the screen for the duration of the block.

Figure 2

Averaged participant reaction times during three blocks of the computerized ecStroop task performed outside the scanner. Only those participants that completed the computerized task both outside and in the scanner environment are represented here.

Figure 3

Regional Grief > Neutral activation in the orbitofrontal cortex (x=4, y=54, z=−10, p=.001, uncorrected) in the Non-Complicated Grief > Nonbereaved group analysis.

Figure 4

Regional Grief > Neutral activation in the rostral/pregenual anterior cingulate cortex (x=−6, y=48, z=14; t=4.25; p < .005, uncorrected) in the Non-Complicated Grief > Nonbereaved group analysis.

Figure 5

Parameter estimates in the orbitofrontal VOI (x=4, y=54, z=−10) contrast; Grief > Neutral stimuli in the Non-Complicated Grief group compared to Nonbereaved controls. Estimates indicate that NCG participants showed significant recruitment of this region, while NB showed little or no recruitment differences across types of stimulus.

Figure 6

Regional Grief Block 4 > Grief Block 1 activation in the dorsal anterior cingulate cortex (x=8, y=22, z=28) in the Complicated Grief group.