Examining Microstructural White Matter in Active Duty Soldiers with a History of Mild Traumatic Brain Injury and Traumatic Stress

Abstract

Background:There is a high comorbidity of posttraumatic stress (PTS) and mild traumatic brain injury (mTBI), with largely overlapping symptomatology, in military service members.Objective:To examine white matter integrity associated with PTS and mTBI as assessed using diffusion tensor imaging (DTI).Method:Seventy-four active-duty U.S. soldiers with PTS (n = 16) and PTS with co-morbid history of mTBI (PTS/mTBI; n = 28) were compared to a military control group (n = 30). Participants received a battery of neurocognitive and clinical symptom measures. The number of abnormal DTI values was determined (>2 SDs from the mean of the control group) for fractional anisotropy (FA) and mean diffusivity (MD), and then compared between groups. In addition, mean DTI values from white matter tracts falling into three categories were compared between groups: (i) projection tracts: superior, middle, and inferior cerebellar peduncles, pontine crossing tract, and corticospinal tract; (ii) association tracts: superior longitudinal fasciculus; and (iii) commissure tracts: cingulum bundle (cingulum-cingulate gyrus and cingulum-hippocampus), and corpus callosum.Results:The comorbid PTS/mTBI group had significantly greater traumatic stress, depression, anxiety, and post-concussive symptoms, and they performed worse on neurocognitive testing than those with PTS alone and controls. The groups differed greatly on several clinical variables, but contrary to what we hypothesized, they did not differ greatly on primary and exploratory analytic approaches of hetero-spatial whole brain DTI analyses.Conclusion:The findings suggest that psychological health conditions rather than pathoanatomical changes may be contributing to symptom presentation in this population.

Altered white matter microstructural organization in posttraumatic stress disorder across 3047 adults: results from the PGC-ENIGMA PTSD consortium

“…Most prior dMRI studies in civilians report lower FA in PTSD [9, 10, 12-14, 16, 17, 21-25, 30-32, 60]. Studies of military cohorts have been mixed, reporting higher FA [26][27][28][29]36], lower FA [8,15,[18][19][20], and null results [33][34][35]. This discrepancy may be due to differences in age, chronicity, and type of trauma exposure, although military personnel may also experience civilian trauma.…”

“…Studies of white matter microstructure in PTSD have reported inconsistent results. The majority report that PTSD is associated with lower FA [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], but some report higher FA [25][26][27][28][29][30][31], higher and lower FA in different regions [32], or null results [33][34][35]. Alterations in the cingulum bundle are frequently reported [9-13, 16, 18, 21, 23-29, 31, 32, 36], with differences also observed in the uncinate, corpus callosum, and corona radiata [14,16,18,19,24,26,29].…”

White matter microstructure varies with post-traumatic stress severity following medical trauma

“…Prior research has largely examined white matter microstructure in chronic PTSD patients. Findings from this prior research have been mixed, with some studies demonstrating significant differences, and others finding no difference, in white matter microstructure between chronic PTSD patients and healthy controls (Dretsch et al 2017;Sanjuan et al 2013). Importantly, changes in white matter microstructure may be delayed following trauma exposure given these changes often occur over weeks to months (Boekel et al 2017;Piervincenzi et al 2017).…”

Altered White Matter Microstructural Organization in Post-Traumatic Stress Disorder across 3,049 Adults: Results from the PGC-ENIGMA PTSD Consortium

“…Most prior dMRI studies in civilians report lower FA in PTSD 9,10,[12][13][14]16,17,[21][22][23][24][25][30][31][32]67 . Studies of military cohorts have been mixed, reporting higher FA [26][27][28][29]36 , lower FA 8,15,[18][19][20] , and null results [33][34][35] . This discrepancy may be due to differences in age, chronicity, and type of trauma exposure, although military personnel often also experience civilian trauma.…”

“…Studies of white matter microstructure in PTSD have reported inconsistent results. The majority report that PTSD is associated with lower FA [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] , but some report higher FA [25][26][27][28][29][30][31] , higher and lower FA in different regions 32 , or null results [33][34][35] .…”