Childhood maltreatment moderates the effect of combat exposure on cingulum structural integrity

Abstract

Limbic white matter pathways link emotion, cognition, and behavior and are potentially malleable to the influences of traumatic events throughout development. However, the impact of interactions between childhood and later life trauma on limbic white matter pathways has yet to be examined. Here, we examined whether childhood maltreatment moderated the effect of combat exposure on diffusion tensor imaging measures within a sample of military veterans (N = 28). We examined five limbic tracts of interest: two components of the cingulum (cingulum, cingulate gyrus, and cingulum hippocampus [CGH]), the uncinate fasciculus, the fornix/stria terminalis, and the anterior limb of the internal capsule. Using effect sizes, clinically meaningful moderator effects were found only within the CGH. Greater combat exposure was associated with decreased CGH fractional anisotropy (overall structural integrity) and increased CGH radial diffusivity (perpendicular water diffusivity) among individuals with more severe childhood maltreatment. Our findings provide preliminary evidence of the moderating effect of childhood maltreatment on the relationship between combat exposure and CGH structural integrity. These differences in CGH structural integrity could have maladaptive implications for emotion and memory, as well as provide a potential mechanism by which childhood maltreatment induces vulnerability to later life trauma exposure.

Figure 1

Three-dimensional representation of tracts of interest. The cingulum, cingulate gyrus (CGC; maroon online), cingulum, hippocampus (CGH; red online), fornix/stria terminalis (FX/ST; blue online), uncinate fasciculus (UNC; green online), and anterior limb of the internal capsule (ALIC; yellow online) tracts of interest are displayed.

Figure 2

Skeletonized diffusion tensor imaging measures within cingulum, hippocampus. (Left) coronal, (middle) sagittal, and (right) axial sections display the cingulum, hippocampus (cyan online) tract of interest overlaid on skeletonized fractional anisotropy (violet online) and radial diffusivity (red online) maps.

Figure 3

Cumulative childhood maltreatment moderated the effect of combat exposure on cingulum, hippocampus structural integrity. Plots display (a) mean fractional anisotropy (FA) and (b) mean radial diffusivity (RD) extracted from the cingulum, hippocampus (CGH) tract of interest. Lines represent predicted FA and RD values at “none” (Childhood Trauma Questionnaire [CTQ] = 25, solid red line online) and “moderate” (CTQ =51, dashed blue line online) CTQ total scores, adjusting for age and past traumatic brain injury. Thus, higher levels of combat exposure accompanied by greater childhood maltreatment was associated with decreased CGH FA and increased CGH RD. Shaded regions depict 95% confidence intervals.

Figure 4

Physical neglect moderated the effect of combat exposure on cingulum, hippocampus structural integrity. Plots display (a) mean fractional anisotropy (FA) and (b) mean radial diffusivity (RD) extracted from the cingulum, hippocampus (CGH) tract of interest. Lines represent predicted FA and RD values at “none” (physical neglect; PN = 5, solid red line online) and “moderate” (PN = 9, dashed blue line online) PN scores, adjusting for age, past traumatic brain injury, and depressive and posttraumatic stress symptoms. Thus, higher levels of combat accompanied by greater childhood PN was associated with decreased CGH FA and increased CGH RD. Shaded regions depict 95% confidence intervals.