Post-traumatic stress disorder vs traumatic brain injury

The negative impact of traumatic brain injury (TBI) on bone in a mouse model

INTRODUCTION

While it is well established that the brain produces hypothalamic hormones and neuropeptides that influence skeletal metabolism, the impact of traumatic brain injury (TBI) on bone is unknown. Based on the recognition from clinical studies that there is an association between TBI and long-term hypothalamic pituitary dysfunction, it was hypothesized that TBI exerts a negative impact on skeletal growth and maintenance.

METHODS

To test the hypothesis, this study employed a repetitive weight drop model for TBI. Four impacts were applied for four consecutive days on 5-week old female C57BL/6 J mice. Bone measurements were taken 2 weeks after the first impact.

RESULTS

Bone mineral content (BMC), bone area (B area) and bone mineral density (BMD) in the total body were reduced by 14.5%, 9.8% and 5.2%, respectively, in the impacted vs. control mice. There was a 17.1% reduction in total volumetric BMD (vBMD) and a 4.0% reduction in material vBMD in cortical bone. In trabecular bone, there was a 44.0% reduction in BV/TV. Although there was no change in the cross-sectional bone size, the tibial growth plate and the tibia itself were shortened.

CONCLUSION

The repetitive animal TBI model produced an immediate, strong negative impact on bone mass acquisition in young mice.

Head injury and loss of consciousness raise the likelihood of developing and maintaining PTSD symptoms

Mild traumatic brain injury has been associated with higher prevalence of posttraumatic stress disorder (PTSD). The extent to which head injury or loss of consciousness predicts PTSD is unknown. To evaluate the contribution of head injury and loss of consciousness to the occurrence of PTSD, we made a longitudinal evaluation of 1,260 road accident survivors admitted to the emergency department with head injury (n = 287), head injury and loss of consciousness (n = 115), or neither (n = 858). A telephone-administered posttraumatic symptoms scale inferred PTSD and quantified PTSD symptoms at 10 days and 8 months after admission. The study groups had similar heart rate, blood pressure, and pain levels in the emergency department. Survivors with loss of consciousness and head injury had higher prevalence of PTSD and higher levels of PTSD symptoms, suggesting that patients with head injury and loss of consciousness reported in the emergency department are at higher risk for PTSD.

Prevalence and Predictors of Post-traumatic Stress Disorder in Adults One Year Following Traumatic Brain Injury: A Population-based Study

Objective: Experiencing a traumatic brain injury (TBI) may increase the risk of post-traumatic stress disorder (PTSD); however, this has not been examined in a population-based context. This study examined prevalence and predictors (demographic and injury related) of PTSD 1 year after TBI in a population-based sample.

Method: A population-based TBI incidence and outcomes study was conducted in Hamilton and Waikato Districts of New Zealand over 12 months (February 2011–March 2012) with follow-up at 1 year. The relationship of baseline demographic and TBI characteristics to PTSD (Post-traumatic Diagnostic Scale; PDS) was examined in 431 adults (>15 years old) 1 year post-TBI.

Results: On average, participants reported three PTSD symptoms, with heightened arousal being the most commonly reported. Nearly 18% of participants met criteria for PTSD. These participants were significantly more likely to report pre-TBI history of depression/anxiety, and to have drugs implicated in the injury. Regression indicated that female gender, increased loss of consciousness (LOC) and intentional injury predicted PTSD severity (R2 = .109, F[6, 294] = 6.007, p < .001) and number of symptoms (R2 = .098, F[3, 297] = 4.562, p < .001).

Conclusion: PTSD occurred as a long-term sequela in 18% of participants after TBI, with increased PTSD severity and greater number of symptoms associated with female gender, longer LOC and intentional injury. These findings have implications for identification and targeting of assessment and intervention resources towards those at greatest risk of PTSD following TBI.

The negative impact of single prolonged stress (SPS) on bone development in mice

Posttraumatic stress disorder (PTSD) disrupts hypothalamic-pituitary-adrenal (HPA) axis function. Given the established role of HPA axis hormones in regulating bone metabolism, we tested the hypothesis that traumatic stress has a negative impact on bone development. We employed a variant single prolonged stress (SPS) model in which several stressors were applied to three week old C57BL/6J mice. Compared to the controls, the stressed mice showed increased freezing behavior reminiscent of PTSD symptoms. At two weeks, bone mineral content (BMC), bone area (B area) and bone mineral density (BMD) in total body based on dual-energy X-ray absorptiometry (DXA) analysis were reduced by 10.2%, 7.0% and 3.6%, respectively. Micro-CT analysis of the metaphyseal region of the excised tibia revealed that SPS caused a deterioration of trabecular architecture with trabecular number (Tb.N), BV/TV, connectivity density (Conn-Den) decreasing 12.0%, 18.9%, 23.3% and trabecular spacing (Tb.Sp), structure model index (SMI) increasing 13.9%, 21.8%, respectively. Mechanical loading increased the cross-sectional area in the mid-shaft region of the loaded right versus unloaded left tibia by 7.6% in the controls, and 10.0% in the stressed mice. Therefore, SPS applied to pre-pubertal young mice produced strong negative impact on both bone mass acquisition and trabecular architecture. Mechanical loading can be employed to increase bone size, a parameter related to bone strength, in normal as well as stressed conditions.

PTSD modifies performance on a task of affective executive control among deployed OEF/OIF veterans with mild traumatic brain injury

Individuals with post-traumatic stress disorder (PTSD) show a cognitive bias for threatening information, reflecting dysregulated executive control for affective stimuli. This study examined whether comorbid mild Traumatic Brain Injury (mTBI) with PTSD exacerbates this bias. A computer-administered Affective Go/No-Go task measured reaction times (RTs) and errors of omission and commission to words with a non-combat-related positive or negative valence in 72 deployed United States service members from the wars in Iraq and Afghanistan. Incidents of military-related mTBI were measured with the Boston Assessment of Traumatic Brain Injury-Lifetime. PTSD symptoms were measured with the Clinician-Administered PTSD Scale. Participants were divided into those with (mTBI+, n = 34) and without a history of military-related mTBI (mTBI-, n = 38). Valence of the target stimuli differentially impacted errors of commission and decision bias (criterion) in the mTBI+ and mTBI- groups. Specifically, within the mTBI+ group, increasing severity of PTSD symptoms was associated with an increasingly liberal response pattern (defined as more commission errors to negative distractors and greater hit rate for positive stimuli) in the positive compared to the negative blocks. This association was not observed in the mTBI- group. This study underscores the importance of considering the impact of a military-related mTBI and PTSD severity upon affective executive control.

Blast-related traumatic brain injury

A bomb blast may cause the full severity range of traumatic brain injury (TBI), from mild concussion to severe, penetrating injury. The pathophysiology of blast-related TBI is distinctive, with injury magnitude dependent on several factors, including blast energy and distance from the blast epicentre. The prevalence of blast-related mild TBI in modern war zones has varied widely, but detection is optimised by battlefield assessment of concussion and follow-up screening of all personnel with potential concussive events. There is substantial overlap between post-concussive syndrome and post-traumatic stress disorder, and blast-related mild TBI seems to increase the risk of post-traumatic stress disorder. Post-concussive syndrome, post-traumatic stress disorder, and chronic pain are a clinical triad in this patient group. Persistent impairment after blast-related mild TBI might be largely attributable to psychological factors, although a causative link between repeated mild TBIs caused by blasts and chronic traumatic encephalopathy has not been established. The application of advanced neuroimaging and the identification of specific molecular biomarkers in serum for diagnosis and prognosis are rapidly advancing, and might help to further categorise these injuries.

Perfusion deficits in patients with mild traumatic brain injury characterized by dynamic susceptibility contrast MRI

Perfusion deficits in patients with mild traumatic brain injury (TBI) from a military population were characterized by dynamic susceptibility contrast perfusion imaging. Relative cerebral blood flow (rCBF) was calculated by a model-independent deconvolution approach from the tracer concentration curves following a bolus injection of gadolinium diethylenetriaminepentaacetate (Gd-DTPA) using both manually and automatically selected arterial input functions (AIFs). Linear regression analysis of the mean values of rCBF from selected regions of interest showed a very good agreement between the two approaches, with a regression coefficient of R = 0.88 and a slope of 0.88. The Bland-Altman plot also illustrated the good agreement between the two approaches, with a mean difference of 0.6 ± 12.4 mL/100 g/min. Voxelwise analysis of rCBF maps from both approaches demonstrated multiple clusters of decreased perfusion (p < 0.01) in the cerebellum, cuneus, cingulate and temporal gyrus in the group with mild TBI relative to the controls. MRI perfusion deficits in the cerebellum and anterior cingulate also correlated (p < 0.01) with neurocognitive results, including the mean reaction time in the Automated Neuropsychological Assessment Metrics and commission error and detection T-scores in the Continuous Performance Test, as well as neurobehavioral scores in the Post-traumatic Stress Disorder Checklist-Civilian Version. In conclusion, rCBF calculated using AIFs selected from an automated approach demonstrated a good agreement with the corresponding results using manually selected AIFs. Group analysis of patients with mild TBI from a military population demonstrated scattered perfusion deficits, which showed significant correlations with measures of verbal memory, speed of reaction time and self-report of stress symptoms.

Surgical inflammatory stress: the embryo takes hold of the reins again

The surgical inflammatory response can be a type of high-grade acute stress response associated with an increasingly complex trophic functional system for using oxygen. This systemic neuro-immune-endocrine response seems to induce the re-expression of 2 extraembryonic-like functional axes, i.e. coelomic-amniotic and trophoblastic-yolk-sac-related, within injured tissues and organs, thus favoring their re-development. Accordingly, through the up-regulation of two systemic inflammatory phenotypes, i.e. neurogenic and immune-related, a gestational-like response using embryonic functions would be induced in the patient's injured tissues and organs, which would therefore result in their repair. Here we establish a comparison between the pathophysiological mechanisms that are produced during the inflammatory response and the physiological mechanisms that are expressed during early embryonic development. In this way, surgical inflammation could be a high-grade stress response whose pathophysiological mechanisms would be based on the recapitulation of ontogenic and phylogenetic-related functions. Thus, the ultimate objective of surgical inflammation, as a gestational process, is creating new tissues/organs for repairing the injured ones. Since surgical inflammation and early embryonic development share common production mechanisms, the factors that hamper the wound healing reaction in surgical patients could be similar to those that impair the gestational process.

Cognitive sequelae of blast-induced traumatic brain injury: recovery and rehabilitation

Blast-related traumatic brain injury (bTBI) poses a significant concern for military personnel engaged in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF). Given the highly stressful context in which such injury occurs, psychiatric comorbidities are common. This paper provides an overview of mild bTBI and discusses the cognitive sequelae and course of recovery typical of mild TBI (mTBI). Complicating factors that arise in the context of co-morbid posttraumatic stress disorder (PTSD) are considered with regard to diagnosis and treatment. Relatively few studies have evaluated the efficacy of cognitive rehabilitation in civilian mTBI, but we discuss cognitive training approaches that hold promise for addressing mild impairments in executive function and memory, akin to those seen in OEF/OIF veterans with bTBI and PTSD. Further research is needed to address the patient and environmental characteristics associated with optimal treatment outcome.