Moral Injury and PTSD: Often Co-Occurring Yet Mechanistically Different
The Journal of Neuropsychiatry and Clinical Neurosciences
FIGURE 1 AND COVER. Recent studies have begun to explore how the underlying neurobiology of posttraumatic stress disorder (PTSD) may be affected by the nature of the index trauma. The results of a meta-analysis that grouped task-activated (trauma reminders) functional MRI (fMRI) studies by PTSD index trauma are color-coded by trauma type (blue, sexual/physical abuse; pink, combat-related) (1). Of note, although areas of greater activation were predominately in the right hemisphere for both
... phere for both groups, there was little or no overlap. One study has compared resting-state regional cerebral metabolic rate between veterans with PTSD grouped by whether the index trauma was danger-and/or fear-based (i.e., life threat to self or other) or nondanger-based (i.e., witnessing violence, traumatic loss, moral injury by self or other). Regions of interest (ROIs) (yellow circles) were areas previously reported to be activated by fear stimuli (bilateral amygdalae, right rostral anterior cingulate cortex) or by traumatic script imagery (right dorsal anterior cingulate cortex, left posterior cingulate cortex, left precuneus). Danger-and/or fear-based traumas were associated with higher metabolism in the amygdala (red fill), whereas nondanger-based traumas were associated with higher metabolism in the precuneus (green fill). As noted by the authors, heightened metabolism in the precuneus for nondanger-based traumas may relate to its role in self-referential processing (2). Moral injury often co-occurs with PTSD. Moral injuries that are index traumas for PTSD are more strongly associated with emotions that developed after the event than emotions experienced during the event, suggesting that the underlying neurobiology may differ (3). An fMRI study of military veterans has explored relationships between resting-state activity (amplitude of low frequency fluctuation [ALFF]) and symptoms of PTSD (Clinician Administered PTSD Scale [CAPS]) and moral injury (Moral Injury Events Scale [MIES]) (4). CAPS score was not significantly correlated with average ALFF in any ROI. Both subscales of the MIES (transgressions, betrayals) correlated with left inferior parietal lobule ROI activity (purple circle) but in opposite directions (Cover). As discussed by the authors, these results indicate that the neural correlates of PTSD and moral injury differ at least in part (4). FIGURE 2. Negative self-referential emotions (guilt, shame) are core symptoms of moral injury. Functional imaging studies of healthy individuals have begun to identify the areas activated by different self-referential emotions (5, 6). A recent meta-analysis of the neural correlates of guilt identified multiple areas, primarily in the left hemisphere (red circles) (6). FIGURE 3. A common theme of interventions to promote healing from moral injury is the importance of forgiveness (9-11). Two studies of healthy individuals have identified neural correlates related to forgiving others for transgressions (12, 13). The task-activated functional MRI (fMRI) study reported higher activity in multiple areas (pink) when participants were instructed to forgive compared with when they were instructed to not forgive offenders (12). The resting-state fMRI study reported that higher scores on the tendency to forgive scale (i.e., more likely to forgive transgressions by others) were negatively correlated with spontaneous activity (amplitude of low frequency fluctuation [ALFF]) in regions associated with mentalizing and self-referential processing (blue) (13). In the absence of studies on selfforgiveness, the neural correlates of loving kindness meditation may be informative. An fMRI study of experienced meditators reported that loving kindness meditation (compared with resting-state) was associated with both increases (orange) and decreases (green) in activity (14) . Of note, the areas of decreased activity partially overlap with areas in which lower resting-state activity correlated with a higher tendency to forgive (13, 14) . Most relevant to understanding the neural correlates of moral injury are studies that utilized autobiographical scenarios to facilitate reexperiencing a self-referential emotional state (7, 8). The reported cortical activations are color-coded by condition and study. Both studies reported activations in the left precuneus/retrosplenial cortex and left inferior frontal gyrus/anterior insular cortex associated with negative (compared with neutral) self-referential scenarios (guilt, shame). These areas were also activated by positive self-referential scenarios (pride) (7).