A comparison of the functional connectome in mild traumatic brain injury and post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) often co-occur in the context of threat to one's life. These conditions also have an overlapping symptomatology and include symptoms of anxiety, poor concentration and memory problems. A major challenge has been articulating the underlying neurobiology of these overlapping conditions. The primary aim of this study was to compare intrinsic functional connectivity between mTBI (without PTSD) and PTSD (without mTBI). The study included functional MRI data from 176 participants: 42 participants with mTBI, 67 with PTSD and a comparison group of 66 age and sex-matched healthy controls. We used network-based statistical analyses for connectome-wide comparisons of intrinsic functional connectivity between mTBI relative to PTSD and controls. Our results showed no connectivity differences between mTBI and PTSD groups. However, we did find that mTBI had significantly reduced connectivity relative to healthy controls within an extensive network of regions including default mode, executive control, visual and auditory networks. The mTBI group also displayed hyperconnectivity between dorsal and ventral attention networks and perceptual regions. The PTSD group also demonstrated abnormal connectivity within these networks relative to controls. Connectivity alterations were not associated with severity of PTSD or post-concussive symptoms in either clinical group. Taken together, the similar profiles of intrinsic connectivity alterations in these two conditions provide neural evidence that can explain, in part, the overlapping symptomatology between mTBI and PTSD.

Reappraisal-related neural predictors of treatment response to cognitive behavior therapy for post-traumatic stress disorder.

BACKGROUND: Although trauma-focused cognitive behavior therapy (TF-CBT) is the frontline treatment for post-traumatic stress disorder (PTSD), one-third of patients are treatment non-responders. To identify neural markers of treatment response to TF-CBT when participants are reappraising aversive material. METHODS: This study assessed PTSD patients (n = 37) prior to TF-CBT during functional magnetic brain resonance imaging (fMRI) when they reappraised or watched traumatic images. Patients then underwent nine sessions of TF-CBT, and were then assessed for symptom severity on the Clinician-Administered PTSD Scale. FMRI responses for cognitive reappraisal and emotional reactivity contrasts of traumatic images were correlated with the reduction of PTSD severity from pretreatment to post-treatment. RESULTS: Symptom improvement was associated with decreased activation of the left amygdala during reappraisal, but increased activation of bilateral amygdala and hippocampus during emotional reactivity prior to treatment. Lower connectivity of the left amygdala to the subgenual anterior cingulate cortex, pregenual anterior cingulate cortex, and right insula, and that between the left hippocampus and right amygdala were also associated with symptom improvement. CONCLUSIONS: These findings provide evidence that optimal treatment response to TF-CBT involves the capacity to engage emotional networks during emotional processing, and also to reduce the engagement of these networks when down-regulating emotions.

White matter anisotropy and response to cognitive behavior therapy for posttraumatic stress disorder.

Trauma-focused cognitive behavior therapy (TF-CBT) is the gold standard treatment for posttraumatic stress disorder (PTSD), up to one-half of PTSD patients remain treatment non-responders. Although studies have used functional MRI to understand the neurobiology of treatment response, there is less understanding of the role of white matter brain structures in response to TF-CBT. Thirty-six treatment-seeking PTSD patients and 33 age-gender matched healthy controls completed diffusion-weighted imaging scans at baseline. Patients underwent nine sessions of TF-CBT treatment and PTSD symptom severity was assessed with the Clinician-Administered PTSD Scale before and after completing treatment. Patients were assessed to estimate the reduction in overall symptoms and also specifically fear and dysphoric symptoms of PTSD. Tract-based spatial statistical analyses were performed for the PTSD group to evaluate whole-brain correlations of fractional anisotropy (FA) with improvement in overall, fear, and dysphoric symptoms using non-parametric permutation inference testing (pFWE < 0.05). Next, we evaluated if these significant measures also characterized PTSD from controls. Greater improvement in dysphoric symptoms was found correlated with lower FA in white matter regions associated with the limbic system, frontal cortex, thalamic association and projection fibers, corpus callosum, and tracts related to the brainstem. White matter anisotropy was not found associated with either overall or fear symptoms. FA in the significant clusters was similar between PTSD and controls. White-matter related to key functional regions may also play an important role in response to TF-CBT. Our results underscore the heterogeneity of PTSD and the need to evaluate distinct symptom phenotypes in treatment studies.

Diffusion Tensor Imaging Analysis of Mild Traumatic Brain Injury and Posttraumatic Stress Disorder.

BACKGROUND: Debate exists over the extent to which dysfunctions arising from mild traumatic brain injury (mTBI) are distinct from posttraumatic stress disorder (PTSD). METHODS: This study investigated 1) the white matter integrity of participants with either mTBI or PTSD, and 2) the relationship between white matter integrity and postconcussive syndrome. The sample comprised 110 civilians (mTBI group = 40; PTSD group = 32; age- and sex-matched trauma-exposed control subjects = 38) recruited from community advertising. Indicators of white matter abnormalities were fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. PTSD symptoms were indexed by the Clinician-Administered PTSD Scale, and postconcussive symptoms were assessed using the Somatic and Psychological Health Report measure. RESULTS: Fractional anisotropy was reduced in mTBI participants in the corpus callosum, tracts of the brainstem, projection fibers, association fibers, and limbic fibers compared with both PTSD and trauma-exposed control subjects. This decrease in fractional anisotropy was observed in the context of concurrent changes in radial diffusivity, axial diffusivity, and mean diffusivity. Postconcussive symptoms were largely explained by PTSD severity rather than by changes in brain white matter. mTBI appears to be characterized by distinct reductions in white matter integrity, and this cannot be attributed to PTSD. CONCLUSIONS: PTSD symptoms appear to be more strongly associated with postconcussive syndrome than with white matter compromise. These findings extend epidemiological evidence of the relative associations of PTSD and mTBI with postconcussive syndrome.

Highways of the emotional intellect: white matter microstructural correlates of an ability-based measure of emotional intelligence.

Individuals differ in their ability to understand emotional information and apply that understanding to make decisions and solve problems effectively - a construct known as Emotional Intelligence (EI). While considerable evidence supports the importance of EI in social and occupational functioning, the neural underpinnings of this capacity are relatively unexplored. We used Tract-Based Spatial Statistics (TBSS) to determine the white matter correlates of EI as measured by the ability-based Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Participants included 32 healthy adults (16 men; 16 women), aged 18-45 years. White matter integrity in key tracts was positively correlated with the Strategic Area branches of the MSCEIT (Understanding Emotions and Managing Emotions), but not the Experiential branches (Perceiving and Facilitating Emotions). Specifically, the Understanding Emotions branch was associated with greater fractional anisotropy (FA) within somatosensory and sensory-motor fiber bundles, particularly those of the left superior longitudinal fasciculus and corticospinal tract. Managing Emotions was associated with greater FA within frontal-affective association tracts including the anterior forceps and right uncinate fasciculus, along with frontal-parietal cingulum and interhemispheric corpus callosum tracts. These findings suggest that specific components of EI are directly related to the structural microarchitecture of major axonal pathways.

Dysregulation in cortical reactivity to emotional faces in PTSD patients with high dissociation symptoms.

BACKGROUND: Predominant dissociation in posttraumatic stress disorder (PTSD) is characterized by restricted affective responses to positive stimuli. To date, no studies have examined neural responses to a range of emotional expressions in PTSD with high dissociative symptoms. OBJECTIVE: This study tested the hypothesis that PTSD patients with high dissociative symptoms will display increased event-related potential (ERP) amplitudes in early components (N1, P1) to threatening faces (angry, fearful), and reduced later ERP amplitudes (Vertex Positive Potential (VPP), P3) to happy faces compared to PTSD patients with low dissociative symptoms. METHODS: Thirty-nine civilians with PTSD were classified as high dissociative (n=16) or low dissociative (n=23) according to their responses on the Clinician Administered Dissociative States Scale. ERPs were recorded, whilst participants viewed emotional (happy, angry, fear) and neutral facial expressions in a passive viewing task. RESULTS: High dissociative PTSD patients displayed significantly increased N120 amplitude to the majority of facial expressions (neutral, happy, and angry) compared to low dissociative PTSD patients under conscious and preconscious conditions. The high dissociative PTSD group had significantly reduced VPP amplitude to happy faces in the conscious condition. CONCLUSION: High dissociative PTSD patients displayed increased early (preconscious) cortical responses to emotional stimuli, and specific reductions to happy facial expressions in later (conscious), face-specific components compared to low dissociative PTSD patients. Dissociation in PTSD may act to increase initial pre-attentive processing of affective stimuli, and specifically reduce cortical reactivity to happy faces when consciously processing these stimuli.