Factor analysis of the neurobehavioral symptom inventory in veterans with PTSD and no history of mild TBI

A Baseline Model of PTSD From the ACES Cohort

INTRODUCTION

Post-traumatic stress disorder (PTSD) is a primary military psychiatric condition with complex etiology including strong genetic and/or environmental influences. Environmental influences and demographics can play a role in supporting underlying genetic traits for clinical utility evaluation as risk modifying factors. We are undertaking an IRB approved study to evaluate polygenic scores of PTSD risk in the adverse childhood experience and serotonin (ACES) transporter cohort.

MATERIALS AND METHODS

Baseline demographic characteristics and statistical modeling of 291 active duty service members from ACES cohort were used and excluded individuals with traumatic brain injury-induced loss of consciousness, pre-deployment PTSD or anxiety disorder, and pre-deployment prescription of antidepressants or psychoactive medications. Summary of categorical and numerical variables were evaluated using chi-square and t-test, respectively. We model PTSD risk and associated scores using linear and logistic regressions.

RESULTS

The ACES subset was 79.1% males, multi-ancestry, and mean age of 38.3 years. Most PTSD individuals received behavioral therapy (89.6%) and/or prescribed antidepressants (67%) had higher scores in ACES, combat exposure scales, PTSD checklist military version, neurobehavioral symptom inventory, Pittsburg sleep quality index, insomnia severity index, and composite autonomic symptom score surveys and were less likely to expect future deployment. A positive correlation between age, total months deployed, ACES, CES, PCL-M, and positive-PTSD diagnosis were consistent but not in older individuals, who were more likely and frequently deployed although increasing risk for combat exposure.

CONCLUSION

Demographic characteristics of the ACES cohort fit a coherent model of risk for PTSD to evaluate polygenic scores. Additional research is merited to understand PTSD effects on these confounding factors.

Regional associations of white matter integrity and neurological, post-traumatic stress disorder and autonomic symptoms in Veterans with and without history of loss of consciousness in mild TBI

Background

Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) share overlapping symptom presentations and are highly comorbid conditions among Veteran populations. Despite elevated presentations of PTSD after mTBI, mechanisms linking the two are unclear, although both have been associated with alterations in white matter and disruptions in autonomic regulation. The present study aimed to determine if there is regional variability in white matter correlates of symptom severity and autonomic functioning in a mixed sample of Veterans with and without PTSD and/or mTBI (N = 77).

Methods

Diffusion-weighted images were processed to extract fractional anisotropy (FA) values for major white matter structures. The PTSD Checklist-Military version (PCL-M) and Neurobehavioral Symptom Inventory (NSI) were used to determine symptom domains within PTSD and mTBI. Autonomic function was assessed using continuous blood pressure and respiratory sinus arrythmia during a static, standing angle positional test. Mixed-effect models were used to assess the regional specificity of associations between symptom severity and white matter, with FA, global symptom severity (score), and white matter tract (tract) as predictors. Additional interaction terms of symptom domain (i.e., NSI and PCL-M subscales) and loss of consciousness (LoC) were added to evaluate potential moderating effects. A parallel analysis was conducted to explore concordance with autonomic functioning.

Results

Results from the two-way Score × Tract interaction suggested that global symptom severity was associated with FA in the cingulum angular bundle (positive) and uncinate fasciculus (negative) only, without variability by symptom domain. We also found regional specificity in the relationship between FA and autonomic function, such that FA was positively associated with autonomic function in all tracts except the cingulum angular bundle. History of LoC moderated the association for both global symptom severity and autonomic function.

Conclusions

Our findings are consistent with previous literature suggesting that there is significant overlap in the symptom presentation in TBI and PTSD, and white matter variability associated with LoC in mTBI may be associated with increased PTSD-spectra symptoms. Further research on treatment response in patients with both mTBI history and PTSD incorporating imaging and autonomic assessment may be valuable in understanding the role of brain injury in treatment outcomes and inform treatment design.