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. 2017 Aug;11(4):1129-1138.
doi: 10.1007/s11682-016-9593-7.

White matter abnormalities are associated with overall cognitive status in blast-related mTBI

Danielle R Miller  1   2 , Jasmeet P Hayes  3   4   5 , Ginette Lafleche  6   4 , David H Salat  5   7   8 , Mieke Verfaellie  6   4
Affiliations

White matter abnormalities are associated with overall cognitive status in blast-related mTBI

Danielle R Miller et al. Brain Imaging Behav. 2017 Aug.

Abstract

Blast-related mild traumatic brain injury (mTBI) is a common injury of the Iraq and Afghanistan Wars. Research has suggested that blast-related mTBI is associated with chronic white matter abnormalities, which in turn are associated with impairment in neurocognitive function. However, findings are inconsistent as to which domains of cognition are affected by TBI-related white matter disruption. Recent evidence that white matter abnormalities associated with blast-related mTBI are spatially variable raises the possibility that the associated cognitive impairment is also heterogeneous. Thus, the goals of this study were to examine (1) whether mTBI-related white matter abnormalities are associated with overall cognitive status and (2) whether white matter abnormalities provide a mechanism by which mTBI influences cognition. Ninety-six Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OEF) veterans were assigned to one of three groups: no-TBI, mTBI without loss of consciousness (LOC) (mTBI-LOC), and mTBI with LOC (mTBI + LOC). Participants were given a battery of neuropsychological tests that were selected for their sensitivity to mTBI. Results showed that number of white matter abnormalities was associated with the odds of having clinically significant cognitive impairment. A mediation analysis revealed that mTBI + LOC was indirectly associated with cognitive impairment through its effect on white matter integrity. These results suggest that cognitive difficulties in blast-related mTBI can be linked to injury-induced neural changes when taking into account the variability of injury as well as the heterogeneity in cognitive deficits across individuals.

Keywords: Cognitive impairment; DTI; Loss of consciousness; White matter integrity; mTBI.

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Conflict of interest statement

CONFLICT OF INTEREST

Danielle R. Miller, Jasmeet P. Hayes, Ginette Lafleche, David H. Salat, and Mieke Verfaellie declare they have no conflict of interest.

Figures

Fig. 1
Fig. 1. Mean number of clusters with reduced FA for each group
Note: For interpretation purposes, figure displays untransformed number of clusters with reduced FA. *=significant group difference from the no-TBI group, P=0.001. Error bars reflect standard error of the mean. FA=fractional anisotropy; mTBI=mild traumatic brain injury; LOC=loss of consciousness
Fig. 2
Fig. 2. Distribution of white matter clusters with reduced FA within groups
Scale indicates the proportion of individuals within each group that have a cluster of reduced FA in the area marked. FA=fractional anisotropy; mTBI=mild traumatic brain injury; LOC=loss of consciousness
Fig. 3
Fig. 3. Number of subjects who had impairment in each factor
Note: three subjects had impairment on more than one factor
Fig. 4
Fig. 4. mTBI+LOC indirectly influences the likelihood of having cognitive impairment through its effect on number of clusters with reduced FA
Numbers shown represent unstandardized coefficients. Solid lines indicate significance (P < 0.05). Gray indicates covariates in the model. FA=fractional anisotropy; mTBI=mild traumatic brain injury; LOC=loss of consciousness; CAPS=Clinician Administered PTSD Scale; WTAR=Wechsler Test of Adult Reading
See this image and copyright information in PMC

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