Gender as a moderator of memory after traumatic brain injury in children

Processing Speed in Children with Traumatic Brain Injury

Abstract: Traumatic brain injury (TBI) is a common cause of childhood morbidity and mortality. Information processing speed (IPS) is a central construct of neuropsychology and a mediator for a range of cognitive functions. In adults, the negative effects of TBI on IPS are well documented. This review qualitatively describes the impact of TBI on IPS in children and adolescents and examines various influencing factors. We included a total of 37 studies in the review that explored IPS using various clinical assessments. These clinical assessments often examine other neuropsychological functions besides IPS. In 29 of these studies, we found a negative effect of TBI on IPS. While injury severity has small but consistent effects on IPS, the effects of age at injury, time since injury, and gender were less evident. Because it is a central construct of neuropsychological functions, IPS should be assessed after TBI.

Understanding Traumatic Brain Injury in Females: A State-of-the-Art Summary and Future Directions

In this report, we identify existing issues and challenges related to research on traumatic brain injury (TBI) in females and provide future directions for research. In 2017, the National Institutes of Health, in partnership with the Center for Neuroscience and Regenerative Medicine and the Defense and Veterans Brain Injury Center, hosted a workshop that focused on the unique challenges facing researchers, clinicians, patients, and other stakeholders regarding TBI in women. The goal of this "Understanding TBI in Women" workshop was to bring together researchers and clinicians to identify knowledge gaps, best practices, and target populations in research on females and/or sex differences within the field of TBI. The workshop, and the current literature, clearly highlighted that females have been underrepresented in TBI studies and clinical trials and have often been excluded (or ovariectomized) in preclinical studies. Such an absence in research on females has led to an incomplete, and perhaps inaccurate, understanding of TBI in females. The presentations and discussions centered on the existing knowledge regarding sex differences in TBI research and how these differences could be incorporated in preclinical and clinical efforts going forward. Now, a little over 2 years later, we summarize the issues and state of the science that emerged from the "Understanding TBI in Women" workshop while incorporating updates where they exist. Overall, despite some progress, there remains an abundance of research focused on males and relatively little explicitly on females.

Clinical Utility of the Child and Adolescent Memory Profile (ChAMP) After Pediatric Traumatic Brain Injury

Sixty-one children and adolescents with traumatic brain injury completed the Child and Adolescent Memory Profile (ChAMP; Sherman & Brooks, 2015) within 1 to 12 months post injury. Most of the ChAMP index scores demonstrated statistically significant negative correlations with time to follow commands following traumatic brain injury. Compared with demographically matched neurologically healthy controls, selected from the ChAMP standardization sample, participants with traumatic brain injury had statistically significantly lower scores on all ChAMP index scores but sensitivity and specificity were suboptimal. We conclude that the ChAMP has modest clinical utility as part of a more comprehensive evaluation of sequelae of traumatic brain injury in children and adolescents.

Familial Risk Factors and Emotional Problems in Early Childhood: The Promotive and Protective Role of Children's Self-Efficacy and Self-Concept

The present study aimed to examine the promotive and protective role of general self-efficacy and positive self-concept in the context of the effects of early familial risk factors on children’s development of emotional problems from early to middle childhood. A total of 293 (T1; M_age = 2.81), 239 (T2; M_age = 3.76), and 189 (T3; M_age = 9.69) children from 25 childcare centers took part in the present study. Fourteen familial risk factors were assessed at T1 using an interview and a questionnaire that were administered to children’s primary caregivers. These 14 familial risk factors were used to compute a familial risk factors score. Primary caregivers also reported on their children’s emotional problems at T2 and T3 and on their children’s general self-efficacy at T2. Children reported on their positive self-concept at T2. Results showed that early familial risk factors were positively associated with emotional problems in the short and long term, although the long-term effect was small and non-significant. Further, the pattern of effect sizes of both promotive and protective effects of general self-efficacy as well as positive self-concept was found to be consistent in the short term. However, in the long term, no consistent support for either the promotive or the protective role of general self-efficacy or positive self-concept was found. These results suggest that general self-efficacy and positive self-concept might contribute to promote mental health and to protect from undesired effects of familial risk factors in the short term. Possible reasons for a lack of long-term effects are discussed along with practical implications.

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.

Sex Differences in Traumatic Brain Injury: What We Know and What We Should Know

There is growing recognition of the problem of male bias in neuroscience research, including in the field of traumatic brain injury (TBI) where fewer women than men are recruited to clinical trials and male rodents have predominantly been used as an experimental injury model. Despite TBI being a leading cause of mortality and disability worldwide, sex differences in pathophysiology and recovery are poorly understood, limiting clinical care and successful drug development. Given growing interest in sex as a biological variable affecting injury outcomes and treatment efficacy, there is a clear need to summarize sex differences in TBI. This scoping review presents an overview of current knowledge of sex differences in TBI and a comparison of human and animal studies. We found that overall, human studies report worse outcomes in women than men, whereas animal studies report better outcomes in females than males. However, closer examination shows that multiple factors including injury severity, sample size, and experimental injury model may differentially interact with sex to affect TBI outcomes. Additionally, we explore how sex differences in mitochondrial structure and function might contribute to possible sex differences in TBI outcomes. We propose recommendations for future investigations of sex differences in TBI, which we hope will lead to improved patient management, prognosis, and translation of therapies from bench to bedside.

Sex differences in pediatric traumatic brain injury

The response of the developing brain to traumatic injury is different from the response of the mature, adult brain. There are critical developmental trajectories in the young brain, whereby injury can lead to long term functional abnormalities. Emerging preclinical and clinical literature supports the presence of significant sex differences in both the response to and the recovery from pediatric traumatic brain injury (TBI). These sex differences are seen at all pediatric ages, including neonates/infants, pre-pubertal children, and adolescents. As importantly, the response to neuroprotective therapies or treatments can differ between male and females subjects. These sex differences can result from several biologic origins, and may manifest differently during the various phases of brain and body development. Recognizing and understanding these potential sex differences is crucial, and should be considered in both preclinical and clinical studies of pediatric TBI.

A Repeated Measures Pilot Comparison of Trajectories of Fluctuating Endogenous Hormones in Young Women with Traumatic Brain Injury, Healthy Controls

Objective

To compare baseline and 72-hour hormone levels in women with traumatic brain injury (TBI) and controls.

Setting

Hospital emergency department.

Participants

21 women ages 18-35 with TBI and 21 controls.

Design

Repeated measures.

Main Measures

Serum samples at baseline and 72 hours; immunoassays for estradiol (E2), progesterone (PRO), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and cortisol (CORT); and health history.

Results

Women with TBI had lower E2 (p = 0.042) and higher CORT (p = 0.028) levels over time. Lower Glasgow Coma Scale (GSC) and OCs were associated with lower FSH (GCS p = 0.021; OCs p = 0.016) and higher CORT (GCS p = 0.001; OCs p = 0.008).

Conclusion

Acute TBI may suppress E2 and increase CORT in young women. OCs appeared to independently affect CORT and FSH responses. Future work is needed with a larger sample to characterize TBI effects on women's endogenous hormone response to injury and OC use's effects on post-TBI stress response and gonadal function, as well as secondary injury.

Does gender matter? Differences in social-emotional behavior among infants and toddlers before and after mild traumatic brain injury: a preliminary study

Traumatic brain injury is a common cause of acquired disability in childhood. While much is known about cognitive sequelae of brain trauma, gender-specific social-emotional problems in children with mild traumatic brain injury is far less understood. The aims of the study were to investigate gender differences in social-emotional behavior before and after mild traumatic brain injury. Thirty-five 3- to 65-month-old children with mild traumatic brain injury and 70 controls were assessed with Ages and Stages Questionnaires: Social-Emotional. Nine months later, 27 of 35 patients and 54 of 70 controls were reassessed. We found that before injury, boys had more self-regulation and autonomy difficulties and girls had problems with adaptive functioning. Nine months after injury, boys continued to struggle with self-regulation and autonomy and new difficulties with interaction had emerged, whereas in girls, problems in interaction had evolved. Even mild traumatic brain injury in early childhood disrupts normal social-emotional development having especially devastating influence on interaction skills.

Post-concussive symptoms and neuropsychological performance in the post-acute period following pediatric mild traumatic brain injury

OBJECTIVE

There is evidence that children after mild traumatic brain injuries (mTBI) suffer ongoing post-concussive symptoms (PCS). However, results concerning neuropsychological outcome after mTBI are controversial. Thus, our aim was to examine group differences regarding neuropsychological outcome and PCS. Additionally, we explored the influence of current and pre-injury everyday attention problems on neuropsychological outcome in children after mTBI.

METHOD

In a prospective short-term longitudinal study, 40 children (aged 6-16 years) after mTBI and 38 children after orthopedic injury (OI) underwent neuropsychological, socio-behavioral and PCS assessments in the acute stage and at 1 week, at 4 weeks, and 4 months after the injury.

RESULTS

Parents of children after mTBI observed significantly more PCS compared to parents of children after OI, especially in the acute stage. Our results revealed no neuropsychological or socio-behavioral differences over time between both groups. However, in children after mTBI, we found negative correlations between elevated levels of everyday attention problems and reduced neuropsychological performance. Furthermore, there was a negative influence of pre-injury everyday attention problems on neuropsychological performance in children after mTBI.

CONCLUSION

In accordance with earlier studies, parents of children after mTBI initially observed significantly more PCS compared to parents of children after OI. There were no neuropsychological or socio-behavioral group differences between children after mTBI and OI in the post-acute period. However, our exploratory findings concerning the influence of everyday attention problems on neuropsychological outcome indicate that current and pre-injury everyday attention problems were negatively associated with neuropsychological performance in children after mTBI.

Individual profiles of predictors and their relations to 10 years outcome after childhood traumatic brain injury

BACKGROUND

Outcome after childhood traumatic brain injury (CTBI) is heterogeneous, with several predictors influencing long-term outcome.

METHOD

This exploratory study used person-oriented cluster analysis to investigate individual profiles of medical, psychological and social predictors and their relation to longitudinal development in a sample of 127 participants with mild, moderate and severe CTBI. Outcome of cognitive, adaptive and academic function was measured at 30 months and 10 years post-injury.

RESULTS

A nine-cluster solution, explaining 67% of the variance in the sample, resulted in two clusters with individuals with mostly mild injuries, five with mostly moderate injured individuals and two clusters with severely injured individuals. Best outcome at 10 years post-injury had a cluster with individuals with moderate injuries, young age at injury, average socioeconomic status (SES) and high pre-injury adaptive function. Worst outcome had a small cluster with severely injured individuals, young age at injury, average SES and average pre-injury adaptive function.

CONCLUSIONS

The findings suggest that pre-injury adaptive function is an influential predictor of outcome following moderate CTBI. Age at injury in the severe group appears to have increased influence over time, with younger age at injury associated with reduced outcome at 10 years after severe CTBI.

Increased CSF concentrations of myelin basic protein after TBI in infants and children: absence of significant effect of therapeutic hypothermia

BACKGROUND

The objectives of this study were to determine effects of severe traumatic brain injury (TBI) on cerebrospinal fluid (CSF) concentrations of myelin basic protein (MBP) and to assess relationships between clinical variables and CSF MBP concentrations.

METHODS

We measured serial CSF MBP concentrations in children enrolled in a randomized controlled trial evaluating therapeutic hypothermia (TH) after severe pediatric TBI. Control CSF was obtained from children evaluated, but found not to be having CNS infection. Generalized estimating equation models and Wilcoxon Rank-Sum test were used for comparisons of MBP concentrations.

RESULTS

There were 27 TBI cases and 57 controls. Overall mean (± SEM) TBI case MBP concentrations for 5 days after injury were markedly greater than controls (50.49 ± 6.97 vs. 0.11 ± 0.01 ng/ml, p < 0.01). Mean MBP concentrations were lower in TBI patients <1 year versus >1 year (9.18 ± 1.67 vs. 60.22 ± 8.26 ng/ml, p = 0.03), as well as in cases with abusive head trauma (AHT) versus non-abusive TBI (14.46 ± 3.15 vs. 61.17 ± 8.65 ng/ml, p = 0.03). TH did not affect MBP concentrations.

CONCLUSIONS

Mean CSF MBP increases markedly after severe pediatric TBI, but is not affected by TH. Infancy and AHT are associated with low MBP concentrations, suggesting that age-dependent myelination influences MBP concentrations after injury. Given the magnitude of MBP increases, axonal injury likely represents an important therapeutic target in pediatric TBI.

Influence of Sex and ERK MAPK on the Pressure Reactivity Index in Newborn Piglets After Fluid Percussion Injury

Greater impairment in autoregulation is seen in male versus female piglets following fluid percussion injury (FPI). This is partially mediated by a greater upregulation of extracellular signal-related kinase mitogen-activated protein kinase (ERK MAPK). We hypothesized that these trends would be reflected by the pressure reactivity index (PRx), a clinical measure of autoregulation. We further hypothesized that PRx values would correlate well with pial artery dilatory responses to hypotension. Male and female piglets were subjected to FPI and treated with a vehicle or ERK MAPK antagonist U 0126 (1 mg/kg IV) 30 min post-injury. FPI led to upregulation of CSF ERK MAPK in untreated piglets of both sexes, however significantly higher PRx values were seen in male versus female piglets. Following administration of U 0126, elevation of ERK MAPK levels was blocked in both sexes and PRx values were significantly improved in the male. A strong correlation was seen between the PRx and pial artery vasomotor activity. These data support previous observations that male piglets demonstrate reversible ERK MAPK-mediated impairment in autoregulation following FPI, which is reflected by the PRx. The strong correlation between the PRx and pial artery vasomotor activity supports the practice of continuously monitoring cerebrovascular autoregulation in patients using this index.

Zinc, vitamin A, and glutamine supplementation in Brazilian shantytown children at risk for diarrhea results in sex-specific improvements in verbal learning

OBJECTIVE

To identify the impact of supplemental zinc, vitamin A, and glutamine, alone or in combination, on long-term cognitive outcomes among Brazilian shantytown children with low median height-for-age z-scores.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted in children aged three months to nine years old from the urban shanty compound community of Fortaleza, Brazil. Demographic and anthropometric information was assessed. The random treatment groups available for cognitive testing (total of 167 children) were: (1) placebo, n = 25; (2) glutamine, n = 23; (3) zinc, n = 18; (4) vitamin A, n = 19; (5) glutamine+zinc, n = 20; (6) glutamine+vitamin A, n = 21; (7) zinc+vitamin A, n = 23; and (8) glutamine+zinc+vitamin A, n = 18. Neuropsychological tests were administered for the cognitive domains of non-verbal intelligence and abstraction, psychomotor speed, verbal memory and recall ability, and semantic and phonetic verbal fluency. Statistical analyses were performed using SPSS, version 16.0. ClinicalTrials.gov: NCT00133406.

RESULTS

Girls receiving a combination of glutamine, zinc, and vitamin A had higher mean age-adjusted verbal learning scores than girls receiving only placebo (9.5 versus 6.4, p = 0.007) and girls receiving zinc+vitamin A (9.5 versus 6.5, p = 0.006). Similar group differences were not found between male study children.

CONCLUSIONS

The findings suggest that combination therapy offers a sex-specific advantage on tests of verbal learning, similar to that seen among female patients following traumatic brain injury.

Influence of Sex and ERK MAPK on the Pressure Reactivity Index in Newborn Piglets After Fluid Percussion Injury

Greater impairment in autoregulation is seen in male versus female piglets following fluid percussion injury (FPI). This is partially mediated by a greater upregulation of extracellular signal-related kinase mitogen-activated protein kinase (ERK MAPK). We hypothesized that these trends would be reflected by the pressure reactivity index (PRx), a clinical measure of autoregulation. We further hypothesized that PRx values would correlate well with pial artery dilatory responses to hypotension. Male and female piglets were subjected to FPI and treated with a vehicle or ERK MAPK antagonist U 0126 (1 mg/kg IV) 30 min post-injury. FPI led to upregulation of CSF ERK MAPK in untreated piglets of both sexes, however significantly higher PRx values were seen in male versus female piglets. Following administration of U 0126, elevation of ERK MAPK levels was blocked in both sexes and PRx values were significantly improved in the male. A strong correlation was seen between the PRx and pial artery vasomotor activity. These data support previous observations that male piglets demonstrate reversible ERK MAPK-mediated impairment in autoregulation following FPI, which is reflected by the PRx. The strong correlation between the PRx and pial artery vasomotor activity supports the practice of continuously monitoring cerebrovascular autoregulation in patients using this index.

α-Synuclein levels are elevated in cerebrospinal fluid following traumatic brain injury in infants and children: the effect of therapeutic hypothermia

α-Synuclein is one of the most abundant proteins in presynaptic terminals. Normal expression of α-synuclein is essential for neuronal survival and it prevents the initiation of apoptosis in neurons through covalent cross-linking of cytochrome c released from mitochondria. Exocytosis of α-synuclein occurs with neuronal mitochondrial dysfunction, making its detection in cerebrospinal fluid (CSF) of children after severe traumatic brain injury (TBI) a potentially important marker of injury. Experimental therapeutic hypothermia (TH) improves mitochondrial function and attenuates cell death, and therefore may also affect CSF α-synuclein concentrations. We assessed α-synuclein levels in CSF of 47 infants and children with severe TBI using a commercial ELISA for detection of monomeric protein. 23 patients were randomized to TH based on published protocols where cooling (32-33°C) was initiated within 6-24 h, maintained for 48 h, and then followed by slow rewarming. CSF samples were obtained continuously via an intraventricular catheter for 6 days after TBI. Control CSF (n = 9) was sampled from children receiving lumbar puncture for CSF analysis of infection that was proven negative. Associations of initial Glasgow Coma Scale (GCS) score, age, gender, treatment, mechanism of injury and Glasgow Outcome Scale (GOS) score with CSF α-synuclein were compared by multivariate regression analysis. CSF α-synuclein levels were elevated in TBI patients compared to controls (p = 0.0093), with a temporal profile showing an early, approximately 5-fold increase on days 1-3 followed by a delayed, >10-fold increase on days 4-6 versus control. α-Synuclein levels were higher in patients treated with normothermia versus hypothermia (p = 0.0033), in patients aged <4 years versus ≥4 years (p < 0.0001), in females versus males (p = 0.0007), in nonaccidental TBI versus accidental TBI victims (p = 0.0003), and in patients with global versus focal injury on computed tomography of the brain (p = 0.046). Comparisons of CSF α-synuclein levels with initial GCS and GOS scores were not statistically significant. Further studies are needed to evaluate the conformational status of α-synuclein in CSF, and whether TH affects α-synuclein aggregation.

Impaired cerebral blood flow autoregulation during posttraumatic arterial hypotension after fluid percussion brain injury is prevented by phenylephrine in female but exacerbated in male piglets by extracellular signal-related kinase mitogen-activated protein kinase upregulation

OBJECTIVE

Traumatic brain injury contributes to morbidity and mortality in children and boys are disproportionately represented. Hypotension is common and worsens outcome after traumatic brain injury. Extracellular signal-related kinase mitogen-activated protein kinase is upregulated and reduces cerebral blood flow after fluid percussion brain injury in piglets. We hypothesized that increased cerebral perfusion pressure through phenylephrine sex dependently reduces impairment of cerebral autoregulation during hypotension after fluid percussion brain injury through modulation of extracellular signal-related kinase mitogen-activated protein kinase.

DESIGN

Prospective, randomized animal study.

SETTING

University laboratory.

SUBJECTS

Newborn (1- to 5-day-old) pigs.

INTERVENTIONS

Cerebral blood flow, pial artery diameter, intracranial pressure, and autoregulatory index were determined before and after fluid percussion brain injury in untreated, preinjury, and postinjury phenylephrine (1 microg/kg/min intravenously) treated male and female pigs during normotension and hemorrhagic hypotension. Cerebrospinal fluid extracellular signal-related kinase mitogen-activated protein kinase was determined by enzyme-linked immunosorbent assay.

MEASUREMENTS AND MAIN RESULTS

Reductions in pial artery diameter, cerebral blood flow, cerebral perfusion pressure, and elevated intracranial pressure after fluid percussion brain injury were greater in males, which were blunted by phenylephrine pre- or postfluid percussion brain injury. During hypotension and fluid percussion brain injury, pial artery dilation was impaired more in males. Phenylephrine decreased impairment of hypotensive pial artery dilation after fluid percussion brain injury in females, but paradoxically caused vasoconstriction after fluid percussion brain injury in males. Papaverine-induced pial artery vasodilation was unchanged by fluid percussion brain injury and phenylephrine. Cerebral blood flow, cerebral perfusion pressure, and autoregulatory index decreased markedly during hypotension and fluid percussion brain injury in males but less in females. Phenylephrine prevented reductions in cerebral blood flow, cerebral perfusion pressure, and autoregulatory index during hypotension in females but increased reductions in males. Cerebrospinal fluid extracellular signal-related kinase mitogen-activated protein kinase was increased more in males than females after fluid percussion brain injury. Phenylephrine blunted extracellular signal-related kinase mitogen-activated protein kinase upregulation in females but increased extracellular signal-related kinase mitogen-activated protein kinase upregulation in males after fluid percussion brain injury.

CONCLUSIONS

These data indicate that elevation of cerebral perfusion pressure with phenylephrine sex dependently prevents impairment of cerebral autoregulation during hypotension after fluid percussion brain injury through modulation of extracellular signal-related kinase mitogen-activated protein kinase. These data suggest the potential role for sex-dependent mechanisms in cerebral autoregulation after pediatric traumatic brain injury.

Sex differences in outcome after mild traumatic brain injury

The objective of this study was to estimate the independent association of sex with outcome after mild traumatic brain injury (mTBI). We performed an analysis of a subset of an established cohort involving 1425 mTBI patients presenting to an academic emergency department (ED). The associations between sex and three outcomes determined 3 months after the initial ED visit were examined: post-concussive symptom (PCS) score (0, 1-5, 6-16, and >16), the number of days to return of normal activities (0, 1-7, and >7), and the number of days of work missed (0, 1-7,and >7). Logistic regression analyses were used to determine the relationship between sex and each outcome after controlling for 12 relevant subject-level variables. Of the 1425 subjects, 643 (45.1%) were female and 782 (54.9%) were male. Three months after mTBI, males had significantly lower odds of being in a higher PCS score category (odds ratio [OR] 0.62, 95% confidence interval [CI]: 0.50, 0.78); this association appeared to be more prominent during child-bearing years for females. Males and females did not significantly differ with respect to the odds of poorer outcome as defined by the number of days to return of normal activities or the number of days of work missed. Female sex is associated with significantly higher odds of poor outcome after mTBI, as measured by PCS score, after control for appropriate confounders. The observed pattern of peak disability for females during the child-bearing years suggests disruption of endogenous estrogen or progesterone production. Attempts to better understand how mTBI affects production of these hormones acutely after injury and during the recovery period may shed light on the mechanism behind poorer outcome among females and putative therapeutic interventions.

Adrenomedullin prevents sex-dependent impairment of autoregulation during hypotension after piglet brain injury through inhibition of ERK MAPK upregulation

Cerebrospinal fluid (CSF) adrenomedullin (ADM) levels are increased in female, but remain unchanged in male, piglets after fluid percussion injury (FPI) of the brain. Subthreshold vascular concentrations of ADM restore impaired hypotensive pial artery dilation after FPI more in males than females. Extracellular signal-related kinase (ERK) mitogen-activated protein kinase (MAPK) is upregulated and contributes to reductions in cerebral blood flow (CBF) after FPI. We hypothesized that ADM prevents sex-dependent impairment of autoregulation during hypotension after FPI through inhibition of ERK MAPK upregulation. FPI increased ERK MAPK more in males than in females. CBF was unchanged during hypotension in sham animals, was reduced more in males than in females after FPI during normotension, and was further reduced in males than in females during hypotension and after FPI. ADM and the ERK MAPK antagonist U 0126 prevented reductions in CBF during hypotension and FPI more in males than in females. Transcranial Doppler (TCD) blood flow velocity was unchanged during hypotension in sham animals, was decreased during hypotension and FPI in male but not in female pigs, and was ameliorated by ADM. Intracranial pressure (ICP) was increased after FPI more in male than in female animals. ADM blunted elevated ICP during FPI and hypotension in males, but not in females. ADM prevented reductions in cerebral perfusion pressure (CPP) during FPI and hypotension in males but not in females. The calculated autoregulatory index was unchanged during hypotension in sham animals, but was reduced more in males than females during hypotension and FPI. ADM prevented reductions in autoregulation during hypotension and FPI more in males than females. These data indicate that ADM prevented loss of cerebral autoregulation after FPI in a sex-dependent and ERK MAPK-dependent manner.

Does gender influence cognitive outcome after traumatic brain injury?

The aim of this study was to determine whether males and females differ in post-acute cognitive outcome following traumatic brain injury (TBI). Performances of 83 men and 75 women with mild to severe TBI were compared on measures of cognitive functions typically impacted by TBI (i.e., processing speed, executive functioning, and memory). Participants completed selected subtests of the Cambridge Neuropsychological Test Automated Battery (CANTAB). Among the participants with mild TBI, women scored significantly higher than men on a test of visual memory. There were no other significant gender differences in cognitive outcomes. These findings overall suggest that cognitive outcome after TBI does not differ according to gender, with the possible exception of memory functioning. Further research is needed to replicate this finding and determine which moderating variables may impact on the relationship between gender and cognitive outcome after TBI.

Gender-Moderated Dorsolateral Prefrontal Reductions in 22q11.2 Deletion Syndrome: Implications for Risk for Schizophrenia

To investigate the impact of the microdeletion on morphology of the prefrontal cortex in 22q11.2 Deletion Syndrome (22q11.2 DS), high-resolution, anatomic magnetic resonance imaging was performed on 19 children and adolescents with 22q11.2 DS (11 females, 8 males) and 18 unaffected controls (10 females, 8 males). Tissue volumes of the dorsolateral, dorsomedial, orbitolateral, and orbitomedial prefrontal cortex were measured. Tasks of executive function and working memory were administered to investigate the association between anatomy and function. Whole brain volume and frontal lobe tissue volume were preserved in girls but reduced in boys with 22q11.2 DS relative to age-matched controls. Dorsolateral prefrontal cortex (DLPFC) volumes were reduced in participants with 22q11.2 DS, although the gender-by-diagnosis effect found for frontal lobe was not as robust for DLPFC. DLPFC volumes were associated with performance on tasks of planning and emotional facial recognition. Longitudinal studies are needed to clarify whether gender differences in frontal lobe and DLPFC persist with development, and whether the volumes of the DLPFC are associated with eventual deterioration in adaptive/psychosocial function that may presage the onset of schizophrenia, for which individuals with 22q11.2 DS are at a disproportionately high risk.

Gender differences in long-term beneficial effects of erythropoietin given after neonatal stroke in postnatal day-7 rats

Recently, we reported that erythropoietin attenuates neonatal brain injury caused by focal cerebral ischemia. The long-term effects of erythropoietin on focal cerebral ischemia-induced injury to the developing brain and the potential gender differences in these long-term effects have not been studied in detail. The current study demonstrated a similarity in the mean infarct volume in both the vehicle-treated male and female rats at 6 and 12 weeks after focal cerebral ischemia. On the other hand, erythropoietin treatment (1000 U/kg x three doses after focal cerebral ischemia) caused a significant reduction in the mean infarct volume in both males and females at 6 weeks after focal cerebral ischemia when compared with the corresponding vehicle-treated animals (males: 141.4+/-48.2 mm3 vs. 194.0+/-59.2 mm3, P<0.05; females: 85.4+/-31.6 mm3 vs. 183.4+/-46.3 mm3, P<0.05). Interestingly, the reduction in the mean infarct volume in the erythropoietin-treated males was significantly less than that in the erythropoietin-treated females at 6 weeks after focal cerebral ischemia (141.4+/-48.2 mm3 vs. 85.4+/-31.6 mm3, P<0.05). At 12 weeks after focal cerebral ischemia, the mean infarct volume in the erythropoietin-treated males significantly increased to 181.0+/-50.4 mm3 (P<0.05). In contrast, the mean infarct volume in the erythropoietin-treated females remained stable (87.0+/-41.7 mm3). Additionally, erythropoietin treatment significantly improved sensorimotor function recovery with a misstep number similar to the sham-operation group at 6 and 12 weeks after focal cerebral ischemia. Moreover, the mean number of missteps in the erythropoietin-treated females was less than that in males at 6 (13.5+/-2.0 vs. 24.5+/-2.5, P<0.05) and 12 (12.5+/-2.0 vs. 20.0+/-2.0, P<0.05) weeks after focal cerebral ischemia. These results indicate that erythropoietin administration after focal cerebral ischemia produces a significant long-term neuroprotective benefit on the developing brain, and that this effect is more beneficial in the female rats.

Sex differences in outcome following sports-related concussion

OBJECT

Females comprise an increasing percentage of the athlete population across all age groups, and analysis of recent literature reveals that they sustain more concussions in collegiate sports. Results of human and animal studies indicate that females may have poorer outcomes after traumatic brain injury; however, no return-to-play guideline takes sex or other individual differences into account. In the present study the authors evaluated the influence of patient sex on objective neurocognitive performance and subjective reporting of symptoms following sports-related concussion.

METHODS

According to preseason baseline neurocognitive computerized testing in 2340 male and female high school and collegiate athletes, individuals who sustained sports-related concussions (155 persons) were reevaluated using an alternate form of the cognitive test. Sex differences in the magnitude of cognitive change from baseline levels and the subjective experience of symptoms were analyzed. To account for the possible protective effects of helmets, comparisons were performed among females, males with helmets, and males without helmets; none of the female athletes wore helmets. Female athletes had significantly greater declines in simple and complex reaction times relative to preseason baseline levels, and they reported more postconcussion symptoms compared with males. As a group, females were cognitively impaired approximately 1.7 times more frequently than males following concussions. Furthermore, females experienced more objective and subjective adverse effects from concussion even after adjusting for the use of helmets by some groups of male athletes (for example, in football).

CONCLUSIONS

Return-to-play decisions and concussion management must be objective and made on an individual basis, including consideration of factors such as patient sex rather than relying on a one-size-fits-all guideline.

Predictors of neuropsychological test performance after pediatric traumatic brain injury

The influence of neurological and demographic variables on neuropsychological test performance was examined in 100 9-to 16-year-old children with traumatic brain injury (TBI). Regression analyses were conducted to determine the relative contributions of coma, neuroimaging findings, ethnicity, socioeconomic status, and gender to variance in performance on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III), California Verbal Learning Test--Children's Version (CVLT-C), and the Children's Category Test. Both neurological and demographic variables contributed to performance on various WISC-III factor index scores as well as the CVLT-C. No evidence for a moderating effect of demographic variables was found, but speed of information processing mediated the effect of neurological and demographic variables on CLVT-C performance. It is concluded that demographic variables have an incremental effect on the neuropsychological test performance of children with TBI above and beyond the influence of injury severity.