Decision making after pediatric traumatic brain injury: trajectory of recovery and relationship to age and gender

Perturbations in risk/reward decision making and frontal cortical catecholamine regulation induced by mild traumatic brain injury

Mild traumatic brain injury (mTBI) disrupts cognitive processes that influence risk taking behavior. Little is known regarding the effects of repetitive mild injury (rmTBI) or whether these outcomes are sex specific. Risk/reward decision making is mediated by the prefrontal cortex (PFC), which is densely innervated by catecholaminergic fibers. Aberrant PFC catecholamine activity has been documented following TBI and may underlie TBI-induced risky behavior. The present study characterized the effects of rmTBI on risk/reward decision making behavior and catecholamine transmitter regulatory proteins within the PFC. Rats were exposed to sham, single (smTBI), or three closed-head controlled cortical impact (CH-CCI) injuries and assessed for injury-induced effects on risk/reward decision making using a probabilistic discounting task (PDT). In the first week post-final surgery, mTBI increased risky choice preference. By the fourth week, males exhibited increased latencies to make risky choices following rmTBI, demonstrating a delayed effect on processing speed. When levels of tyrosine hydroxylase (TH) and the norepinephrine reuptake transporter (NET) were measured within subregions of the PFC, females exhibited dramatic increases of TH levels within the orbitofrontal cortex (OFC) following smTBI. However, both males and females demonstrated reduced levels of OFC NET following rmTBI. These results indicate the OFC is susceptible to catecholamine instability after rmTBI and suggests that not all areas of the PFC contribute equally to TBI-induced imbalances. Overall, the CH-CCI model of rmTBI has revealed time-dependent and sex-specific changes in risk/reward decision making and catecholamine regulation following repetitive mild head injuries.

Visualization of the Intracranial Pressure and Time Burden in Childhood Brain Trauma: What We Have Learned One Decade on With KidsBrainIT

To validate the intracranial pressure (ICP) dose-response visualization plot for the first time in a novel prospectively collected pediatric traumatic brain injury (pTBI) data set from the multi-center, multi-national KidsBrainIT consortium. Prospectively collected minute-by-minute ICP and mean arterial blood pressure time series of 104 pTBI patients were categorized in ICP intensity-duration episodes. These episodes were correlated with the 6-month Glasgow Outcome Score (GOS) and displayed in a color-coded ICP dose-response plot. The influence of cerebrovascular reactivity and cerebral perfusion pressure (CPP) were investigated. The generated ICP dose-response plot on the novel data set was similar to the previously published pediatric plot. This study confirmed that higher ICP episodes were tolerated for a shorter duration of time, with an approximately exponential decay curve delineating the positive and negative association zones. ICP above 20 mm Hg for any duration in time was associated with poor outcome in our patients. Cerebrovascular reactivity state did not influence their respective transition curves above 10 mm Hg ICP. CPP below 50 mm Hg was not tolerated, regardless of ICP and duration, and was associated with worse outcome. The ICP dose-response plot was reproduced in a novel and independent pTBI data set. ICP above 20 mm Hg and CPP below 50 mm Hg for any duration in time were associated with worse outcome. This highlighted a pressing need to reduce pediatric ICP therapeutic thresholds used at the bedside.

The decision-making task: Development and evaluation in a paediatric traumatic brain injury population

Assessment measures that quantify decision-making abilities in children and adolescents are limited. In the current study, a novel computerized Decision-Making Task (DMT), which identifies the process that is involved in decision-making, was developed based on an existing information-boards paradigm. The overall aim was to validate the DMT in a paediatric TBI population. This prospective study investigated the performance on the DMT for children post-TBI (n = 49; 7-15 years) compared to typically developing controls (n = 22; 7-15 years), and investigated the psychometric properties of the DMT by examining internal consistency-related reliability, convergent validity (measures of decision-making, working memory, functional outcomes, and behaviour), and divergent validity (vocabulary). Significant differences were detected for performance on the DMT between children post-TBI and the control group. Psychometric properties of the DMT were acceptable, with variable findings for convergent validity (working memory, functional outcomes, and behaviour). This is the first study to develop and investigate a novel computerised task to assess decision-making skills in a paediatric TBI population. Results cautiously suggest that the DMT is a valid and a reliable measure of decision-making in our clinical sample.

Pediatric Traumatic Brain Injury: An Update on Preclinical Models, Clinical Biomarkers, and the Implications of Cerebrovascular Dysfunction

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality. Recent studies suggest that children and adolescents have worse post-TBI outcomes and take longer to recover than adults. However, the pathophysiology and progression of TBI in the pediatric population are studied to a far lesser extent compared to the adult population. Common causes of TBI in children are falls, sports/recreation-related injuries, non-accidental trauma, and motor vehicle-related injuries. A fundamental understanding of TBI pathophysiology is crucial in preventing long-term brain injury sequelae. Animal models of TBI have played an essential role in addressing the knowledge gaps relating to pTBI pathophysiology. Moreover, a better understanding of clinical biomarkers is crucial to diagnose pTBI and accurately predict long-term outcomes. This review examines the current preclinical models of pTBI, the implications of pTBI on the brain’s vasculature, and clinical pTBI biomarkers. Finally, we conclude the review by speculating on the emerging role of the gut-brain axis in pTBI pathophysiology.

Paediatric traumatic brain injury and the dysregulation profile: The mediating role of decision-making

Decision-making is often impacted by paediatric traumatic brain injury (TBI). However, there are few tools available to assess these skills in children, with even less research on the consequences of decision-making deficits on dysregulation following TBI. This prospective preliminary study investigated whether decision-making mediated the effect of TBI on dysregulation in children. The performance of school-aged children aged between 7 and 15 years with TBI (n = 49) and that of typically developing controls (n = 22) was compared on The Decision-making Task, and on parent ratings of the dysregulation profile as characterized by the Child Behaviour Checklist-Dysregulation Profile. Relative to the Control group, the TBI group performed more poorly on the decision-making task, and parents of the TBI group rated their children to be more poorly on the dysregulation profile. Mediation analyses indicated that decision-making mediated the relationship between TBI and the dysregulation profile. Our preliminary findings suggest the need for further research in the area of decision-making, and its impact on dysregulated behaviours in children following TBI.

Diffusion Tensor Imaging Correlates of Resilience Following Adolescent Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is associated with considerable mortality and morbidity in adolescents, but positive outcomes are possible. Resilience is the concept that some individuals flourish despite significant adversity.

OBJECTIVE

To determine if there is a relationship between resilience-promoting factors that are known to promote resilience and white matter (WM) microstructure 1 year after complicated mild TBI or moderate or severe TBI that is sustained by adolescents.

METHOD

We examined the relationship between performance on a self-report measure of resilience-promoting factors and WM integrity assessed by diffusion tensor imaging in a group of adolescents who had sustained either a TBI (n = 38) or an orthopedic injury (OI) (n = 23).

RESULTS

Immediately following injury, the individuals with TBI and the OI controls had comparable levels of resilience-promoting factors; however, at 1 year post injury, the TBI group endorsed fewer resilience-promoting factors and exhibited WM disruption compared with the OI controls. The individuals with TBI who had more resilience-promoting factors at 1 year post injury exhibited increased WM integrity, but the OI controls did not. Findings were particularly strong for the following structures: anterior corona radiata, anterior limb of the internal capsule, and genu of the corpus callosum-structures that are implicated in social cognition and are frequently disrupted after TBI. Relationships were notable for caregiver and community-level resilience-promoting factors.

CONCLUSION

The current findings are some of the first to indicate neurobiological evidence of previously noted buffering effects of resilience-promoting factors in individuals with TBI.

White Matter Disruption in Pediatric Traumatic Brain Injury: Results From ENIGMA Pediatric Moderate to Severe Traumatic Brain Injury

OBJECTIVE

Our study addressed aims (1) to test the hypothesis that moderate-severe traumatic brain injury (TBI) in pediatric patients is associated with widespread white matter (WM) disruption, (2) to test the hypothesis that age and sex affect WM organization after injury, and (3) to examine associations between WM organization and neurobehavioral outcomes.

METHODS

Data from 10 previously enrolled, existing cohorts recruited from local hospitals and clinics were shared with the Enhancing NeuroImaging Genetics Through Meta-Analysis (ENIGMA) Pediatric Moderate/Severe TBI (msTBI) working group. We conducted a coordinated analysis of diffusion MRI (dMRI) data using the ENIGMA dMRI processing pipeline.

RESULTS

Five hundred seven children and adolescents (244 with complicated msTBI and 263 controls) were included. Patients were clustered into 3 postinjury intervals: acute/subacute, <2 months; postacute, 2 to 6 months; and chronic, ≥6 months. Outcomes were dMRI metrics and postinjury behavioral problems as indexed by the Child Behavior Checklist. Our analyses revealed altered WM diffusion metrics across multiple tracts and all postinjury intervals (effect sizes range d = -0.5 to -1.3). Injury severity is a significant contributor to the extent of WM alterations but explained less variance in dMRI measures with increasing time after injury. We observed a sex-by-group interaction: female patients with TBI had significantly lower fractional anisotropy in the uncinate fasciculus than controls (β = 0.043), which coincided with more parent-reported behavioral problems (β = -0.0027).

CONCLUSIONS

WM disruption after msTBI is widespread, persistent, and influenced by demographic and clinical variables. Future work will test techniques for harmonizing neurocognitive data, enabling more advanced analyses to identify symptom clusters and clinically meaningful patient subtypes.

Traumatic brain injuries and problem gambling in youth: Evidence from a population-based study of secondary students in Ontario, Canada

Traumatic brain injury (TBI) is characterized by a change in brain function after an external force or sudden movement to the head. TBI is associated with risk-taking, impulsivity, psychological distress, substance abuse, and violent crime. Previous studies have also linked problem gambling to TBI, but these studies have not controlled for possible confounding variables such as mental health problems and hazardous drinking which are also linked to TBI. This study examines the relationship between problem gambling and TBI among adolescents. Data were obtained from the 2011, 2013 and 2015 cycles of the OSDUHS, a biennial cross-sectional school-based study of children in grades 7 to 12 (N = 9,198). Logistic regression was used to estimate adjusted odds ratios (AOR) in controlled and uncontrolled analyses. Adjusting for sex and grade only, problem gambling was associated with a history of TBI (AOR = 2.8). This association remained significant after adjusting for hazardous drinking and suicidality (AOR = 2.0). In addition, problem gambling had a statistically significant relationship with being male (AOR = 4.7), hazardous drinking (AOR = 4.5), and suicidality (AOR = 3.1). This study provides further data to suggest a link between TBI and problem gambling. However, research is needed on the causal relationship between these variables and the potential implications for treatment and prevention.

Sex differences in traumatic brain injury: a multi-dimensional exploration in genes, hormones, cells, individuals, and society

Traumatic brain injury (TBI) is exceptionally prevalent in society and often imposes a massive burden on patients' families and poor prognosis. The evidence reviewed here suggests that gender can influence clinical outcomes of TBI in many aspects, ranges from patients' mortality and short-term outcome to their long-term outcome, as well as the incidence of cognitive impairment. We mainly focused on the causes and mechanisms underlying the differences between male and female after TBI, from both biological and sociological views. As it turns out that multiple factors contribute to the gender differences after TBI, not merely the perspective of gender and sex hormones. Centered on this, we discussed how female steroid hormones exert neuroprotective effects through the anti-inflammatory and antioxidant mechanism, along with the cognitive impairment and the social integration problems it caused. As to the treatment, both instant and long-term treatment of TBI requires adjustments according to gender. A further study with more focus on this topic is therefore suggested to provide better treatment options for these patients.

Rehabilitation of Executive function in Paediatric Traumatic brain injury (REPeaT): protocol for a randomized controlled trial for treating working memory and decision-making

BACKGROUND

Working memory allows us to hold information in an active state for short periods of time, and is essential in facilitating goal directed cognitive functioning. Difficulties in working memory and decision-making are common post childhood Traumatic Brain Injury (TBI). Despite this, there is a paucity of research pertaining to implementation and effectiveness of interventions to reduce these common difficulties which impact significantly on one's ability to function independently. One such intervention, Cogmed Working Memory Training Program, has shown success in improving working memory in other childhood clinical populations, but has received little evaluation in the TBI area. This study aims to evaluate whether Cogmed improves working memory and decision-making post childhood TBI and whether these benefits generalize to functional areas.

METHODS

The study is a randomized controlled trial (RCT) of the Cogmed (RM version) intervention for children post-TBI. Children aged 7-15 years are initially screened for working memory impairments. Eligible participants are then randomized into either the treatment group (Cogmed) or the active-control group (Lexia Reading). Each group trains online for 50 min each day, 5 days per week, for 5 consecutive weeks. The online training is supported by online clinician meetings each week. Outcome neuropsychological and functional assessments are carried out immediately at the completion of the intervention and at 6 months follow-up.

DISCUSSION

This study follows gold standard methodology in intervention research; uses a novel measure of decision-making; measures the effects of intervention on functional outcomes immediately and longer-term post intervention; uses online clinician support in order to allow more families easy access to the program; and promotes the use of technology to improve health services. If efficacious in improving working memory, decision-making, and functional outcomes, our team will then take a key role in implementing Cogmed into clinical care.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12617000085370 . Trial Registration Date: 16/01/2017. Protocol Version/Date: HREC 35181G/18.08.2017. Study Status: Ongoing.

Sex-related responses after traumatic brain injury: Considerations for preclinical modeling

Traumatic brain injury (TBI) has historically been viewed as a primarily male problem, since men are more likely to experience a TBI because of more frequent participation in activities that increase risk of head injuries. This male bias is also reflected in preclinical research where mostly male animals have been used in basic and translational science. However, with an aging population in which TBI incidence is increasingly sex-independent due to falls, and increasing female participation in high-risk activities, the attention to potential sex differences in TBI responses and outcomes will become more important. These considerations are especially relevant in designing preclinical animal models of TBI that are more predictive of human responses and outcomes. This review characterizes sex differences following TBI with a special emphasis on the contribution of the female sex hormones, progesterone and estrogen, to these differences. This information is potentially important in developing and customizing TBI treatments.

Parvalbumin fast-spiking interneurons are selectively altered by paediatric traumatic brain injury

KEY POINTS

Traumatic brain injury (TBI) in children remains a leading cause of death and disability and it remains poorly understood why children have worse outcomes and longer recover times. TBI has shown to alter cortical excitability and inhibitory drive onto excitatory neurons, yet few studies have directly examined changes to cortical interneurons. This is addressed in the present study using a clinically relevant model of severe TBI (controlled cortical impact) in interneuron cell type specific Cre-dependent mice. Mice subjected to controlled cortical impact exhibit specific loss of parvalbumin (PV) but not somatostatin immunoreactivity and cell density in the peri-injury zone. PV interneurons are primarily of a fast-spiking (FS) phenotype that persisted in the peri-injury zone but received less frequent inhibitory and stronger excitatory post-synaptic currents. The targeted loss of PV-FS interneurons appears to be distinct from previous reports in adult mice suggesting that TBI-induced pathophysiology is dependent on the age at time of impact.

ABSTRACT

Paediatric traumatic brain injury (TBI) is a leading cause of death and disability in children. Traditionally, ongoing neurodevelopment and neuroplasticity have been considered to confer children with an advantage following TBI. However, recent findings indicate that the paediatric brain may be more sensitive to brain injury. Inhibitory interneurons are essential for proper cortical function and are implicated in the pathophysiology of TBI, yet few studies have directly investigated TBI-induced changes to interneurons themselves. Accordingly, in the present study, we examine how inhibitory neurons are altered following controlled cortical impact (CCI) in juvenile mice with targeted Cre-dependent fluorescence labelling of interneurons (Vgat:Cre/Ai9 and PV:Cre/Ai6). Although CCI failed to alter the number of excitatory neurons or somatostatin-expressing interneurons in the peri-injury zone, it significantly decreased the density of parvalbumin (PV) immunoreactive cells by 71%. However, PV:Cre/Ai6 mice subjected to CCI showed a lower extent of fluorescence labelled cell loss. PV interneurons are predominantly of a fast-spiking (FS) phenotype and, when recorded electrophysiologically from the peri-injury zone, exhibited intrinsic properties similar to those of control neurons. Synaptically, CCI induced a decrease in inhibitory drive onto FS interneurons combined with an increase in the strength of excitatory events. The results of the present study indicate that CCI induced both a loss of PV interneurons and an even greater loss of PV expression. This suggests caution is required when interpreting changes in PV immunoreactivity alone as direct evidence of interneuronal loss. Furthermore, in contrast to reports in adults, TBI in the paediatric brain selectively alters PV-FS interneurons, primarily resulting in a loss of interneuronal inhibition.

Home Environment as a Predictor of Long-Term Executive Functioning following Early Childhood Traumatic Brain Injury

OBJECTIVES

This study examined the relationship of the home environment to long-term executive functioning (EF) following early childhood traumatic brain injury (TBI).

METHODS

Participants (N=134) were drawn from a larger parent study of 3- to 6-year-old children hospitalized for severe TBI (n=16), complicated mild/moderate TBI (n=44), or orthopedic injury (OI; n=74), recruited prospectively at four tertiary care hospitals in the United States and followed for an average of 6.8 years post-injury. Quality of the home environment, caregiver psychological distress, and general family functioning were assessed shortly after injury (i.e., early home) and again at follow-up (i.e., late home). Participants completed several performance-based measures of EF at follow-up. Hierarchical regression analyses examined the early and late home environment measures as predictors of EF, both as main effects and as moderators of group differences.

RESULTS

The early and late home environment were inconsistent predictors of long-term EF across groups. Group differences in EF were significant for only the TEA-Ch Walk/Don't Walk subtest, with poorer performance in the severe TBI group. However, several significant interactions suggested that the home environment moderated group differences in EF, particularly after complicated mild/moderate TBI.

CONCLUSIONS

The home environment is not a consistent predictor of long-term EF in children with early TBI and OI, but may moderate the effects of TBI on EF. The findings suggest that interventions designed to improve the quality of stimulation in children's home environments might reduce the long-term effects of early childhood TBI on EF. (JINS, 2018, 24, 11-21).

Juvenile Traumatic Brain Injury Results in Cognitive Deficits Associated with Impaired Endoplasmic Reticulum Stress and Early Tauopathy

The leading cause of death in the juvenile population is trauma, and in particular neurotrauma. The juvenile brain response to neurotrauma is not completely understood. Endoplasmic reticulum (ER) stress has been shown to contribute to injury expansion and behavioral deficits in adult rodents and furthermore has been seen in adult postmortem human brains diagnosed with chronic traumatic encephalopathy. Whether endoplasmic reticulum stress is increased in juveniles with traumatic brain injury (TBI) is poorly delineated. We investigated this important topic using a juvenile rat controlled cortical impact (CCI) model. We proposed that ER stress would be significantly increased in juvenile rats following TBI and that this would correlate with behavioral deficits using a juvenile rat model. A juvenile rat (postnatal day 28) CCI model was used. Binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP) were measured at 4 h in the ipsilateral pericontusion cortex. Hypoxia-inducible factor (HIF)-1α was measured at 48 h and tau kinase measured at 1 week and 30 days. At 4 h following injury, BiP and CHOP (markers of ER stress) were significantly elevated in rats exposed to TBI. We also found that HIF-1α was significantly upregulated 48 h following TBI showing delayed hypoxia. The early ER stress activation was additionally asso-ciated with the activation of a known tau kinase, glycogen synthase kinase-3β (GSK-3β), by 1 week. Tau oligomers measured by R23 were significantly increased by 30 days following TBI. The biochemical changes following TBI were associated with increased impulsive-like or anti-anxiety behavior measured with the elevated plus maze, deficits in short-term memory measured with novel object recognition, and deficits in spatial memory measured with the Morris water maze in juvenile rats exposed to TBI. These results show that ER stress was increased early in juvenile rats exposed to TBI, that these rats developed tau oligomers over the course of 30 days, and that they had significant short-term and spatial memory deficits following injury.

Sex-dependent changes in neuronal morphology and psychosocial behaviors after pediatric brain injury

Chronic social behavior problems after pediatric traumatic brain injury (TBI) significantly contribute to poor quality of life for survivors. Using a well-characterized mouse model of early childhood TBI, we have previously demonstrated that young brain-injured mice develop social deficits by adulthood. As biological sex may influence both normal and aberrant social development, we here evaluated potential sex differences in post-TBI psychosocial deficits by comparing the behavior of male and female mice at adulthood (8 weeks post-injury). Secondly, we hypothesized that pediatric TBI would influence neuronal morphology identified by Golgi-Cox staining in the hippocampus and prefrontal cortex, regions involved in social cognition and behavior, before the onset of social problems (3 weeks post-injury). Morphological analysis of pyramidal neurons in the ipsilateral prefrontal cortex and granule cells of the hippocampal dentate gyrus revealed a reduction in dendritic complexity after pediatric TBI. This was most apparent in TBI males, whereas neurons from females were less affected. At adulthood, consistent with previous studies, TBI males showed deficits in sociability and social recognition. TBI females also showed a reduction in sociability, but intact social recognition and increased sociosexual avoidance. Together, these findings indicate that sex is a determinant of regional neuroplasticity and social outcomes after pediatric TBI. Reduced neuronal complexity in the prefrontal cortex and hippocampus, several weeks after injury in male mice, appears to precede the subsequent emergence of social deficits. Sex-specific alterations in the social brain network are thus implicated as an underlying mechanism of social dysfunction after pediatric TBI.

Traumatic brain injury in individuals at clinical high risk for psychosis

BACKGROUND

Recent research suggests that a traumatic brain injury (TBI) can significantly increase the risk of later development of psychosis. However, it is unknown whether people at clinical high risk (CHR) of psychosis have experienced TBI at higher rates, compared to otherwise healthy individuals. This study evaluated the prevalence of mild TBI, whether it was related to past trauma and the relationship of mild TBI to later transition to psychosis.

METHODS

Seven-hundred forty-seven CHR and 278 healthy controls (HC) were assessed on past history of mild TBI, age at first and last injury, severity of worst injury and number of injuries using the Traumatic Brain Injury Interview. Attenuated psychotic symptoms were assessed with the Scale of Psychosis-risk Symptoms. IQ was estimated using the Wechsler Abbreviated Scale of Intelligence and past trauma and bullying were recorded using the Childhood Trauma and Abuse Scale.

RESULTS

CHR participants experienced a mild TBI more often than the HC group. CHR participants who had experienced a mild TBI reported greater total trauma and bullying scores than those who had not, and those who experienced a mild TBI and later made the transition to psychosis were significantly younger at the age at first and most recent injury than those who did not.

CONCLUSION

A history of mild TBI is more frequently observed in CHR individuals than in HC. Inclusion or study of CHR youth with more severe TBI may provide additional insights on the relationship between TBI and later transition to psychosis in CHR individuals.

Social dysfunction after pediatric traumatic brain injury: A translational perspective

Social dysfunction is common after traumatic brain injury (TBI), contributing to reduced quality of life for survivors. Factors which influence the development or persistence of social deficits after injury remain poorly understood, particularly in the context of ongoing brain maturation during childhood and adolescence. Aberrant social interactions have recently been modeled in adult and juvenile rodents after experimental TBI, providing an opportunity to gain new insights into the underlying neurobiology of these behaviors. Here, we review our current understanding of social dysfunction in both humans and rodent models of TBI, with a focus on brain injuries acquired during early development. Modulators of social outcomes are discussed, including injury-related and environmental risk and resilience factors. Disruption of social brain network connectivity and aberrant neuroendocrine function are identified as potential mechanisms of social impairments after pediatric TBI. Throughout, we highlight the overlap and disparities between outcome measures and findings from clinical and experimental approaches, and explore the translational potential of future research to prevent or ameliorate social dysfunction after childhood TBI.

Feedback learning and behavior problems after pediatric traumatic brain injury

BACKGROUND

Feedback learning is essential for behavioral development. We investigated feedback learning in relation to behavior problems after pediatric traumatic brain injury (TBI).

METHOD

Children aged 6-13 years diagnosed with TBI (n = 112; 1.7 years post-injury) were compared with children with traumatic control (TC) injury (n = 52). TBI severity was defined as mild TBI without risk factors for complicated TBI (mildRF- TBI, n = 24), mild TBI with ⩾1 risk factor for complicated TBI (mildRF+ TBI, n = 51) and moderate/severe TBI (n = 37). The Probabilistic Learning Test was used to measure feedback learning, assessing the effects of inconsistent feedback on learning and generalization of learning from the learning context to novel contexts. The relation between feedback learning and behavioral functioning rated by parents and teachers was explored.

RESULTS

No evidence was found for an effect of TBI on learning from inconsistent feedback, while the moderate/severe TBI group showed impaired generalization of learning from the learning context to novel contexts (p = 0.03, d = -0.51). Furthermore, the mildRF+ TBI and moderate/severe TBI groups had higher parent and teacher ratings of internalizing problems (p's ⩽ 0.04, d's ⩾ 0.47) than the TC group, while the moderate/severe TBI group also had higher parent ratings of externalizing problems (p = 0.006, d = 0.58). Importantly, poorer generalization of learning predicted higher parent ratings of externalizing problems in children with TBI (p = 0.03, β = -0.21) and had diagnostic utility for the identification of children with TBI and clinically significant externalizing behavior problems (area under the curve = 0.77, p = 0.001).

CONCLUSIONS

Moderate/severe pediatric TBI has a negative impact on generalization of learning, which may contribute to post-injury externalizing problems.

Static and Dynamic Factors Promoting Resilience following Traumatic Brain Injury: A Brief Review

Traumatic brain injury (TBI) is the greatest contributing cause of death and disability among children and young adults in the United States. The current paper briefly summarizes contemporary literature on factors that can improve outcomes (i.e., promote resilience) for children and adults following TBI. For the purpose of this paper, the authors divided these factors into static or unmodifiable factors (i.e., age, sex, intellectual abilities/education, and preinjury psychiatric history) and dynamic or modifiable factors (i.e., socioeconomic status, family functioning/social support, nutrition, and exercise). Drawing on human and animal studies, the research reviewed indicated that these various factors can improve outcomes in multiple domains of functioning (e.g., cognition, emotion regulation, health and wellness, behavior, etc.) following a TBI. However, many of these factors have not been studied across populations, have been limited to preclinical investigations, have been limited in their scope or follow-up, or have not involved a thorough evaluation of outcomes. Thus, although promising, continued research is vital in the area of factors promoting resilience following TBI in children and adults.

Predictors of acute symptomatic seizures after intracranial hemorrhage in infants

OBJECTIVE

To determine the prevalence of acute symptomatic seizures in infants with supratentorial intracranial hemorrhage, to identify potential risk factors, and to determine the effect of acute seizures on long-term morbidity and mortality.

DESIGN

Children less than 24 months with intracranial hemorrhage were identified from a neurocritical care database. All patients who received seizure prophylaxis beginning at admission were included in the study. Risk factors studied were gender, etiology, location of hemorrhage, seizure(s) on presentation, and the presence of parenchymal injury. Acute clinical and electrographic seizures were identified from hospital medical records. Subsequent development of late seizures was determined based on clinical information from patients' latest follow-up.

SETTING AND PATIENTS

Patients with idiopathic neonatal intracranial hemorrhage, premature infants, and those with prior history of seizures were excluded from analysis. Seventy-two infants met inclusion criteria.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty percent of infants had acute symptomatic seizures. The prevalence was similar regardless of whether etiology of hemorrhage was traumatic or nontraumatic. Seizures on presentation and parenchymal injury were independent risk factors of acute seizures (p = 0.001 and p = 0.006, respectively). Younger children and women were also at higher risk (p < 0.05). Twenty percent had electrographic-only seizures, and those with parenchymal injury trended toward an increased risk (p < 0.1). Acute seizures were not predictive of mortality, but nearly twice as many patients with acute seizures developed late seizures when compared with those without. Electrographic seizures and parenchymal injury were also predictive of development of late seizures (p < 0.001 and p = 0.013, respectively).

CONCLUSIONS

Despite seizure prophylaxis, infants with supratentorial intracranial hemorrhage are at high risk for acute symptomatic seizures. This is regardless of the etiology of hemorrhage. Younger patients, women, patients with parenchymal injury, and patients presenting with seizure are most likely to develop acute seizures. Although the benefits of seizure prophylaxis have not been studied in this specific population, these results suggest that it is an important component of acute care following intracranial hemorrhage.

The moderating effects of sex and age on the association between traumatic brain injury and harmful psychological correlates among adolescents

Background

Although it is well established that sex is a risk factor in acquiring a traumatic brain injury (TBI) among adolescents, it has not been established whether it also moderates the influence of other TBI psychological health correlates.

Methods and Findings

Data were derived from a 2011 population-based cross-sectional school survey, which included 9,288 Ontario 7th–12th graders who completed anonymous self-administered questionnaires in classrooms. Response rate was 62%. Preliminary analyses found no evidence of nonresponse bias in the reporting of TBI. TBI was defined as a hit or blow to the head that resulted in a 5 minutes loss of consciousness or at least one overnight hospitalization due to symptoms associated with it. Reports of lifetime TBI were more common among males than females (23.1%, 95% CI: 20.5, 25.8 vs. 17.1%, 95% CI: 14.7, 19.8). Thirteen correlates were examined and included cigarette smoking, elevated psychological distress, suicide ideation, bully victimization (at school, as well as cyber bullying), bullying others, cannabis use, cannabis dependence and drug use problems, physical injuries, daily smoking, drinking alcohol, binge drinking, use of cannabis, and poor academic performance. Among the outcomes examined, sex moderated the relationship between lifetime TBI and cigarette smoking. In addition, sex and age jointly moderated the relationship between lifetime TBI and daily smoking, alcohol use and physical injuries. Late adolescent males who reported lifetime TBI, relative to females, displayed elevated daily smoking and injuries, whereas their females counterparts displayed elevated past year drinking. Possible bias related to self-report procedures and the preclusion of causal inferences due to the cross-sectional nature of the data are limitations of this study.

Conclusions

TBI differences in outcomes need to be assessed for potential moderating effects of sex and age. Results have important implications for more tailored injury prevention efforts.

Differential Expression of Brain Cannabinoid Receptors between Repeatedly Stressed Males and Females may Play a Role in Age and Gender-Related Difference in Traumatic Brain Injury: Implications from Animal Studies

Inconsistent gender differences in the outcome of TBI have been reported. The mechanism is unknown. In a recent male animal study, repeated stress followed by TBI had synergistic effects on brain gene expression and caused greater behavioral deficits. Because females are more likely to develop anxiety after stress and because anxiety is mediated by cannabinoid receptors (CBRs) (CB₁ and CB₂), there is a need to compare CB₁ and CB₂ expression in stressed males and females. CB₁ and CB₂ mRNA expression was determined in the amygdala, hippocampus, prefrontal cortex (PFC), and hypothalamus of adolescent male and female rats after 3 days of repeated tail-shock stress using qPCR. PFC CB₁ and CB₂ protein levels were determined using Western blot techniques. Both gender and stress had significant effects on brain CB₁ mRNA expression levels. Overall, females showed significantly higher CB₁ and CB₂ mRNA levels in all brain regions than males (p < 0.01). Repeated stress reduced CB₁ mRNA levels in the amygdala, hippocampus, and PFC (p < 0.01, each). A gender × stress interaction was found in CB₁ mRNA level in the hippocampus (p < 0.05), hypothalamus (p < 0.01), and PFC (p < 0.01). Within-sex one-way ANOVA analysis showed decreased CB₁ mRNA in the hippocampus, hypothalamus, and PFC of stressed females (p < 0.01, each) but increased CB₁ mRNA levels in the hypothalamus of stressed males (p < 01). There was a gender and stress interaction in prefrontal CB₁ receptor protein levels (p < 0.05), which were decreased in stressed females only (p < 0.05). Prefrontal CB₂ protein levels were decreased in both male and female animals after repeated stress (p < 0.05, each). High basal levels of CBR expression in young naïve females could protect against TBI damage whereas stress-induced CBR deficits could predict a poor outcome of TBI in repeatedly stressed females. Further animal studies could help evaluate this possibility.

A history of low birth weight alters recovery following a future head injury: a case series

OBJECTIVE

Low birth weight (LBW; below 2500 grams) is a general risk factor for a variety of neurodevelopmental difficulties. However, these children may remain more vulnerable to neurologic and environmental insults occurring years later. This prospective case series reports on children who sustained a mild, moderate, or severe traumatic brain injury (TBI) in middle childhood but who had also been born with birth weights below 2500 grams.

PARTICIPANTS

PARTICIPANTS were 14 children with mild, moderate, or severe traumatic brain injury (TBI), 5 of whom had birth weights under 2500 grams (LBW) and 9 children with normal birth weight (NBW). All participants were drawn from a larger study on the long-term cognitive and behavioral impact of pediatric TBI and were matched on age, estimated socioeconomic status (SES), and severity of TBI (with NBW children actually having a slightly worse overall injury severity).

RESULTS

At baseline, both groups exhibited similar scores on WJ-R Letter Word Identification and Calculations, Tower of London number solved, and CVLT-C total correct. Baseline group differences were observed on the CELF-III Formulated Sentences (NBW > LBW) and on the VABS Adaptive Behavior Composite and Socialization subdomain (LBW > NBW). Over 2 years, relative to the NBW group, the LBW group evidenced declines on both WJ-R subtests, CVLT-C total correct, CELF-III Formulated Sentences, and VABS Adaptive Behavior Composite and Socialization.

CONCLUSIONS

Although preliminary in nature due to small sample size, findings suggest a history of LBW influences the recovery trajectory following childhood TBI. Academic and adaptive functioning and verbal memory appeared particularly affected.