Gender differences in executive functions following traumatic brain injury

Factors related to social inferencing performance in moderate-severe, chronic TBI

OBJECTIVE

Following traumatic brain injury (TBI), deficits in social cognition are common. Social inferencing is a crucial component of social cognition that enables an individual to understand the thoughts, feelings, and intentions of a communication partner when this information is not explicitly stated. Existing literature suggests a variety of factors contribute to social inferencing success (e.g. biological sex, executive functioning), yet findings are not conclusive, largely because these factors have been examined in isolation.

METHOD

In this cross-sectional study, stepwise regression with cross validation was used to examine the extent that several theoretically motivated factors were associated with social inferencing (measured by performance on The Awareness of Social Inference Test [TASIT]) in adult participants with TBI (n = 105). Demographic information, executive functioning, aggression, emotional functioning measures, and participation in society were all examined in relation to social inferencing performance.

RESULTS

The findings confirm the importance of higher-level cognitive skills (i.e. executive functioning) in social inferencing, and advance the literature by underlining the potential importance of productive participation in social inferencing performance.

CONCLUSION

This study innovatively highlights factors linked with social inferencing skills and, in doing so, how deficits in social inferencing might manifest in the lives of individuals with TBI.

A literature review of outcome and treatment options after acquired brain injury: Suggestions for adult offenders using knowledge from the general population

BACKGROUND

Acquired brain injury (ABI) is a major health problem, often with negative effects on behaviour and mental health as well as cognition. Prevalence of ABI is exceptionally high among offenders and increases their re-offending risk. Information on risk factors for ABI and its outcomes among offenders that could guide effective treatment for them is, nevertheless, scarce and dispersed. However, there is a more substantial literature about the general population that could inform work with brain-injured offenders, especially when selecting for samples or subgroups with similar relevant characteristics, such as lower socio-economic status (SES), pre-injury lower tested intelligence score (<85) and pre-injury mental health problems.

AIMS

To explore brain injury data from non-offender samples of otherwise similar socio-economic and mental health and ability characteristics to offenders then, first, to describe their untreated outcomes and, secondly, outcomes after frequently used interventions in these circumstances, noting factors associated with their effectiveness.

METHOD

Three databases were systematically searched for the years 2010-2022; first, using terms for brain injury or damage and cognitive (dys)function, mental health or quality of life. Second, in a separate search, we used these terms and terms for interventions and rehabilitation. In the second review, studies were selected for clear, distinguishable data on age, sex, SES and lifestyle factors to facilitate inferences for offenders. A narrative analytical approach was adopted for both reviews.

RESULTS

Samples with characteristics that are typical in offender groups, including lower SES, lower pre-injury intelligence quotient (<85), prior cognitive impairments and prior mental health problems, had poorer cognitive and behavioural outcomes following ABI than those without such additional problems, together with lower treatment adherence. With respect to treatment, adequate motivation and self-awareness were associated with better cognitive and behavioural outcomes than when these were low or absent, regardless of the outcome measured.

CONCLUSIONS

More complex pre-injury mental health problems and social disadvantages typical of offenders are associated with poorer post-brain injury recovery. This paper adds to practical knowledge by bringing together work that follows specific outcome trajectories. Overall, succesful ABI-interventions in the general population that aim at pre-injury difficulties comparable to those seen among offenders, show that personalising injury-specific treatments and taking account of these difficulties, maximised positive outcomes.

Sex/gender differences in service use patterns, clinical outcomes and mortality risk for adults with acquired brain injury: a retrospective cohort study (ABI-RESTART)

OBJECTIVE

To identify sex/gender differences in functional, psychosocial and service use patterns in community-based post-acute care for acquired brain injury.  Design: Retrospective cohort study.

SUBJECTS/PATIENTS

Adults with acquired brain injury enrolled in post-acute neurorehabilitation and disability support in Western Australia (n = 1,011).

METHODS

UK Functional Independence Measure and Functional Assessment Measure (FIM + FAM), Mayo-Portland Adaptability Inventory-4, goal attainment, length of stay (LOS), number of episodes of care and deaths were evaluated using routinely collected clinical and linked administrative data.

RESULTS

At admission, women were older (p < 0.001) and displayed poorer functional independence (FIM + FAM; p < 0.05) compared with men. At discharge, there were no differences in goal attainment, psychosocial function or functional independence between men and women. Both groups demonstrated functional gains; however, women demonstrated clinically significant gains (+ 15.1, p < 0.001) and men did not (+ 13.7, p < 0.001). Women and men had equivalent LOS (p = 0.205). Aboriginal and/or Torres Strait Islander status predicted longer LOS for women but not for men. Being partnered predicted reduced LOS for women but not men. Women had a higher risk of multiple episodes of care (p < 0.001), but not death (p = 0.409), compared with that of men.

CONCLUSION

At admission to rehabilitation and disability support services for acquired brain injury, women have poorer functional independence and higher risk of multiple episodes of care, compared with men, suggesting greater disability in the community. By the time of discharge from these services, women and men make equivalent functional and psychosocial gains. The higher risk of multiple episodes of care for women relative to men suggest women may need additional post-discharge support, to avoid readmission.

Diabetic Encephalopathy in a Preclinical Experimental Model of Type 1 Diabetes Mellitus: Observations in Adult Female Rat

Patients affected by diabetes mellitus (DM) show diabetic encephalopathy with an increased risk of cognitive deficits, dementia and Alzheimer's disease, but the mechanisms are not fully explored. In the male animal models of DM, the development of cognitive impairment seems to be the result of the concomitance of different processes such as neuroinflammation, oxidative stress, mitochondrial dysfunction, and aberrant synaptogenesis. However, even if diabetic encephalopathy shows some sex-dimorphic features, no observations in female rats have been so far reported on these aspects. Therefore, in an experimental model of type 1 DM (T1DM), we explored the impact of one month of pathology on memory abilities by the novel object recognition test and on neuroinflammation, synaptogenesis and mitochondrial functionality. Moreover, given that steroids are involved in memory and learning, we also analysed their levels and receptors. We reported that memory dysfunction can be associated with different features in the female hippocampus and cerebral cortex. Indeed, in the hippocampus, we observed aberrant synaptogenesis and neuroinflammation but not mitochondrial dysfunction and oxidative stress, possibly due to the results of locally increased levels of progesterone metabolites (i.e., dihydroprogesterone and allopregnanolone). These observations suggest specific brain-area effects of T1DM since different alterations are observed in the cerebral cortex.

Gender Differences in Executive Functions of Patients Operated for Mild to Moderate Epidural Hematoma

Background Impairment in neurocognitive functions are commonly followed by Epidural hematoma (EDH) . This cross-sectional study was aimed to study gender differences in neurocognitive functions in mild to moderate epidural hematoma patients (43 male and 19 female patients) post-surgery using standardized assessment tools of comprehensive neurocognitive function attention, speed, working memory, fluency, set-shifting, perseveration, planning and response inhibition.

Methods Descriptive statistics, i.e., mean and standard deviation (SD) values were computed, and a t-test was applied for further exploration.

Results The analysis of results shows that on the test of working memory, female group scored better as significant differences were found on N-Back (2 Back versions) and digit span-backward. On the verbal fluency test (COWA), significant difference was found as females scored higher than the male group on total responses. However, the male group was higher in total time and error than the female group on the test of sustained attention and divided attention.

Conclusion This study shows interesting results in terms of gender differences in executive function of patients operated for mild to moderate epidural hematoma. These findings have significant clinical and implications for planning intervention. The neuropsychological rehabilitation of patients operated for mild to moderate epidural hematoma has a crucial role in enhancing their recovery and overall functioning. Inputs about gender differences in neuro psychological functioning of these patients would help in decision making regarding neuropsychological rehabilitation incorporating the gender related differences too in their intervention plan.

Effects of Progesterone on Preclinical Animal Models of Traumatic Brain Injury: Systematic Review and Meta-analysis

Since the publication of two phase III clinical trials not supporting the use of progesterone in patients with traumatic brain injury (TBI), several possible explanations have been postulated, including limitations in the analysis of results from preclinical evidence. Therefore, to address this question, a systematic review and meta-analysis was performed to evaluate the effects of progesterone as a neuroprotective agent in preclinical animal models of TBI. A total of 48 studies were included for review: 29 evaluated brain edema, 21 evaluated lesion size, and 0 studies reported the survival rate. In the meta-analysis, it was found that progesterone reduced brain edema (effect size - 1.73 [- 2.02, - 1.44], p < 0.0001) and lesion volume (effect size - 0.40 [- 0.65, - 0.14], p = 0.002). Lack of details in the studies hindered the assessment of risk of bias (through the SYRCLE tool). A funnel plot asymmetry was detected, suggesting a possible publication bias. In conclusion, preclinical studies show that progesterone has an anti-edema effect in animal models of TBI, decreasing lesion volume or increasing remaining tissue. However, more studies are needed using assessing methods with lower risk of histological artifacts.

Memory and Executive Functions Subserving Judgments of Learning: Cognitive Reorganization After Traumatic Brain Injury

We investigated relationships between psychometric measures of memory, executive functions (EFs), and task-based measures of Judgments of Learning (JOLs) in individuals with and without Traumatic Brain Injury (TBI), to study functional reorganization after TBI. We hypothesized that, in controls, accuracy of immediate JOLs would be associated with short-term memory and EFs (but not long-term memory, LTM), while accuracy of delayed JOLs would be associated primarily with LTM. We hypothesized that those with good recovery from TBI would demonstrate functional reorganization of the relationships between memory, EFs, and JOLs. Eighteen individuals with TBI and 18 matched controls completed eight neuropsychological tests of memory and EFs. They studied word-pairs, made immediate and delayed JOLs, and took a cued-recall test for the studied word-pairs. Stepwise regression and Lasso analyses generated a predictive model of JOL accuracy for each group. Accuracy of immediate JOLs in controls was predicted by short-term memory, inhibition, switching, and cognitive fluency, while accuracy of delayed JOLs was predicted by verbal recall. In individuals with TBI, inhibition predicted immediate JOL accuracy and switching predicted delayed JOL accuracy. Cognitive reorganization in those with good long-term recovery from TBI may account for the ability to make JOLs with accuracy similar to controls.

Predicting Clinical Outcomes 7-10 Years after Severe Traumatic Brain Injury: Exploring the Prognostic Utility of the IMPACT Lab Model and Cerebrospinal Fluid UCH-L1 and MAP-2

BACKGROUND

Severe traumatic brain injury (TBI) is a major contributor to disability and mortality in the industrialized world. Outcomes of severe TBI are profoundly heterogeneous, complicating outcome prognostication. Several prognostic models have been validated for acute prediction of 6-month global outcomes following TBI (e.g., morbidity/mortality). In this preliminary observational prognostic study, we assess the utility of the International Mission on Prognosis and Analysis of Clinical Trials in TBI (IMPACT) Lab model in predicting longer term global and cognitive outcomes (7-10 years post injury) and the extent to which cerebrospinal fluid (CSF) biomarkers enhance outcome prediction.

METHODS

Very long-term global outcome was assessed in a total of 59 participants (41 of whom did not survive their injuries) using the Glasgow Outcome Scale-Extended and Disability Rating Scale. More detailed outcome information regarding cognitive functioning in daily life was collected from 18 participants surviving to 7-10 years post injury using the Cognitive Subscale of the Functional Independence Measure. A subset (n = 10) of these participants also completed performance-based cognitive testing (Digit Span Test) by telephone. The IMPACT lab model was applied to determine its prognostic value in relation to very long-term outcomes as well as the additive effects of acute CSF ubiquitin C-terminal hydrolase-L1 (UCH-L1) and microtubule associated protein 2 (MAP-2) concentrations.

RESULTS

The IMPACT lab model discriminated favorable versus unfavorable 7- to 10-year outcome with an area under the receiver operating characteristic curve of 0.80. Higher IMPACT lab model risk scores predicted greater extent of very long-term morbidity (β = 0.488 p = 0.000) as well as reduced cognitive independence (β =  - 0.515, p = 0.034). Acute elevations in UCH-L1 levels were also predictive of lesser independence in cognitive activities in daily life at very long-term follow-up (β = 0.286, p = 0.048). Addition of two CSF biomarkers significantly improved prediction of very long-term neuropsychological performance among survivors, with the overall model (including IMPACT lab score, UCH-L1, and MAP-2) explaining 89.6% of variance in cognitive performance 7-10 years post injury (p = 0.008). Higher acute UCH-L1 concentrations were predictive of poorer cognitive performance (β =  - 0.496, p = 0.029), whereas higher acute MAP-2 concentrations demonstrated a strong cognitive protective effect (β = 0.679, p = 0.010).

CONCLUSIONS

Although preliminary, results suggest that existing prognostic models, including models with incorporation of CSF markers, may be applied to predict outcome of severe TBI years after injury. Continued research is needed examining early predictors of longer-term outcomes following TBI to identify potential targets for clinical trials that could impact long-ranging functional and cognitive outcomes.

Functional Connectome Dynamics After Mild Traumatic Brain Injury According to Age and Sex

Neural and cognitive deficits after mild traumatic brain injury (mTBI) are paralleled by changes in resting state functional correlation (FC) networks that mirror post-traumatic pathophysiology effects on functional outcomes. Using functional magnetic resonance images acquired both acutely and chronically after injury (∼1 week and ∼6 months post-injury, respectively), we map post-traumatic FC changes across 136 participants aged 19-79 (52 females), both within and between the brain's seven canonical FC networks: default mode, dorsal attention, frontoparietal, limbic, somatomotor, ventral attention, and visual. Significant sex-dependent FC changes are identified between (A) visual and limbic, and between (B) default mode and somatomotor networks. These changes are significantly associated with specific functional recovery patterns across all cognitive domains (p < 0.05, corrected). Changes in FC between default mode, somatomotor, and ventral attention networks, on the one hand, and both temporal and occipital regions, on the other hand, differ significantly by age group (p < 0.05, corrected), and are paralleled by significant sex differences in cognitive recovery independently of age at injury (p < 0.05, corrected). Whereas females' networks typically feature both significant (p < 0.036, corrected) and insignificant FC changes, males more often exhibit significant FC decreases between networks (e.g., between dorsal attention and limbic, visual and limbic, default-mode and somatomotor networks, p < 0.0001, corrected), all such changes being accompanied by significantly weaker recovery of cognitive function in males, particularly older ones (p < 0.05, corrected). No significant FC changes were found across 35 healthy controls aged 66-92 (20 females). Thus, male sex and older age at injury are risk factors for significant FC alterations whose patterns underlie post-traumatic cognitive deficits. This is the first study to map, systematically, how mTBI impacts FC between major human functional networks.

Allopregnanolone: An overview on its synthesis and effects

Allopregnanolone, a 3α,5α-progesterone metabolite, acts as a potent allosteric modulator of the γ-aminobutyric acid type A receptor. In the present review, the synthesis of this neuroactive steroid occurring in the nervous system is discussed with respect to physiological and pathological conditions. In addition, its physiological and neuroprotective effects are also reported. Interestingly, the levels of this neuroactive steroid, as well as its effects, are sex-dimorphic, suggesting a possible gender medicine based on this neuroactive steroid for neurological disorders. However, allopregnanolone presents low bioavailability and extensive hepatic metabolism, limiting its use as a drug. Therefore, synthetic analogues or a different therapeutic strategy able to increase allopregnanolone levels have been proposed to overcome any pharmacokinetic issues.

An Examination of Social Inferencing Skills in Males and Females Following Traumatic Brain Injury

OBJECTIVE

This study examines sex differences in social inferencing deficits after traumatic brain injury (TBI), and examines the odds of males and females being impaired while controlling for potential confounders.

DESIGN

Cross-sectional survey.

SETTING

Outpatient.USA and a University in Canada.

PARTICIPANTS

One hundred five participants with TBI (60 males, 45 females) and 105 healthy controls (HC; 57 males, 48 females).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The Awareness of Social Inference Test (TASIT), which includes 1) Emotional Evaluation Test (EET), 2) Social Inference-Minimal (SI-M) test, and 3) Social Inference-Enriched (SI-E) test.

RESULTS

Within the HC sample, males and females performed similarly on all three TASIT subtests. Within the TBI group, males had significantly lower scores than females on EET (P = 0.03), SI-M (P=0.01) and SI-E (P=0.04). Using impairment cutoffs derived from the HC sample, significantly more males with TBI (30%) were impaired on the EET than females(16.7%); impairment was similar between males and females on SI-M and SI-E. When adjusting for executive functioning and education, the odds of being impaired on the EET did not significantly differ for males and females (OR = 0.47; 95% CI: 0.16 - 1.40; P = 0.18).

CONCLUSIONS

While more males with TBI have emotion perception deficits than females, the difference appears to be driven by education and executive functioning. Research is needed in larger samples with more definitive norms to better understand social inferencing impairments in males and females with TBI, and translation to interpersonal behaviors.

Literature Review of Sex Differences in mTBI

INTRODUCTION

Traumatic brain injury (TBI) remains a significant source of morbidity worldwide and is of particular concern for the military. Scientific literature examining sex differences in TBI is highly contradictory with some reporting better outcomes in men, others reporting better outcomes in women, and others reporting mixed results or no difference. While the exact cause is currently debated, the existence of such differences has important implications for surveillance techniques, treatment options, and management of long-term consequences. As the number of women within the U.S. military ranks increases and with the opening of combat roles to women in 2013, increased awareness of probable sex differences regarding TBI responses will enable better standard of care.

MATERIALS AND METHODS

Using the PubMed database, a keyword search using gender, "sex factors", "sex dependent", "gender disparity", TBI, "traumatic brain injury", mTBI (mild TBI), and "cranial trauma" was used to identify articles of interest. Results were filtered for written in the last 5 years, English, and free full text. References of relevant articles were cross-checked for additional publications. Articles familiar to the authors were also included.

RESULTS

We review literature that includes analysis of age as an interaction in TBI, hypothesized mechanisms to explain variations in outcomes between men and women, and the need for inclusion of sex as a criterion in future studies.

CONCLUSIONS

Emerging studies underscore the complexity of interpreting sex differences in TBI. The long-held belief that women have a neuroprotective advantage compared to men based on higher levels of sex hormones is being re-evaluated. Past conclusions have relied extensively on clinical studies that include a disproportionate number of men or do not stratify results based on sex. While sex hormones may be neuroprotective, underlying mechanisms are far from clarified. Future TBI studies must include women and gonadal hormone levels should be measured to address potential variables. Given the significant number of TBIs within the military, an improved understanding of TBI pathophysiology and outcomes is important considerations for mission success and servicemember longevity.

Life is about "constant evolution": the experience of living with an acquired brain injury in individuals who report higher or lower posttraumatic growth

OBJECTIVE

To explore the experience of living with an Acquired Brain Injury (ABI) in individuals who report higher or lower posttraumatic growth (PTG).

METHOD

A multi-method design was employed. Participant scores on the Posttraumatic Growth Inventory (PTGI) were used to identify groups for qualitative comparative analysis. Individual semi-structured interviews were conducted with fourteen individuals with ABI. Data were analysed thematically.

RESULTS

Four themes emerged. The first two themes: "In my mind I was fine" surviving in aftermath of acquiring a brain injury and The everyday as "derailing" capture the transition process from an initial rehabilitation state characterised by neuropsychological and avoidance coping, towards active rebuilding for PTG. Internal building blocks for PTG and Growing in the social world: "you need to have that social connection" elaborate on the internal (e.g., acceptance, integration of the pre and post-injury self) and external (e.g., social relationships) factors seen to facilitate or obstruct PTG.

CONCLUSIONS

Under certain conditions, individuals living with ABI may construe positive growth from their experiences. Practitioners can support PTG development by providing individual and family-based supports aimed at increasing acceptance, the integration of self, and social connection throughout all stages of ABI rehabilitation.IMPLICATIONS FOR REHABILITATIONInternal factors such as having a flexible and positive mindset and external factors such as one's social environment can affect how individuals living with an ABI construe positive growth.Individuals with ABI and their families require access to individualised longitudinal support for neuropsychological and social challenges that can result in increased distress and obstruct the development of PTG.Efforts to facilitate acceptance and support the integration of the pre and post-injury self through recognition of continuity of self and processing of new schematic beliefs can benefit PTG development.Rehabilitation providers should support individuals with ABI to develop or maintain a positive social identity within new or existing social groups.

Examining the Relationship Between Community Integration and Mental Health Characteristics of Individuals With Childhood Acquired Neurological Disability

Background: Many individuals with cerebral palsy (CP) or acquired brain injury (ABI) are at higher risk of lowered psychosocial functioning, poor mental health outcomes and decreased opportunities for community integration (CI) as they transition to adulthood. It is imperative to understand the characteristics of those at highest risk of dysfunction so that targeted interventions can be developed to reduce the impact. Methods: This quantitative, cross-sectional study examines current patients of the Living Independently Fully Engaged [(LIFEspan) Service], a tertiary outpatient hospital-based clinic. The Patient Health Questionnaire-4 (PHQ-4) and the Community Integration Questionnaire (CIQ) were administered to participants. Personal health information was also collected from participants' health charts, and participant interviews. Associations of sex and condition with the outcomes of screening for further assessment of depression, screening for further assessment of anxiety, and CI were calculated using t-tests and Chi-square tests. Results: 285 participants completed standardized screening tools for depression and anxiety (PHQ-4) and 283 completed the Community Integration Questionnaire (CIQ). Mean age was 23.4 (4.2) years; 59% were diagnosed with CP, 41% diagnosed with ABI, and 56% were male. A moderate proportion of the sample screened positive for further assessment of anxiety (28%) and depression (16%), and the overall mean score on the CIQ for the sample was 15.8 (SD 5.1). Participants that screened positive for further assessment of depression and anxiety on the PHQ-4 had lower scores on the Social Integration subscale of the CIQ (p = 0.04 and p = 0.036, respectively). Females were found to have significantly higher community integration than males (p = 0.0011) and those diagnosed with ABI were found to have significantly higher community integration than those with CP (p = 0.009), respectively. A weak negative association was found between age for the total sample and overall PHQ-4 score (p = 0.0417). Presence of an intellectual or learning disability/challenge was associated with a lower CIQ score (p = 0.0026). Conclusions: This current study, highlights the need for further research to explore the unique needs and barriers faced by this population. This study may inform assessments and interventions to support the mental health and community integration of this population.

A systematic review and meta-analysis of behavioural sex differences in executive control

Literature investigating whether an individuals' sex affects their executive control abilities and performance on cognitive tasks in a normative population has been contradictory and inconclusive. Using meta-analytic procedures (abiding by PRISMA guidelines), this study attempts to identify the magnitude of behavioural sex differences in three prominent executive control domains of cognitive set-shifting, performance monitoring, and response inhibition. PubMed, Web of Science, and Scopus were systematically searched. Across 46 included studies, a total of 1988 females and 1884 males were included in the analysis. Overall, males and females did not differ on performance in any of the three domains of performance monitoring, response inhibition, or cognitive set-shifting. Task-specific sex differences were observed in the domains of performance monitoring, in the CANTAB Spatial Working Memory task-males scored statistically higher than females (Hedges' g = -0.60), and response inhibition, in the Delay Discounting task-females scored statistically higher than males (Hedges' g = 0.64). While the meta-analysis did not detect overall behavioural sex differences in executive control, significant heterogeneity and task-specific sex differences were found. To further understand sex differences within these specific tasks and domains, future research must better control for age and sex hormone levels.

Integrated Stress Response Inhibitor Reverses Sex-Dependent Behavioral and Cell-Specific Deficits after Mild Repetitive Head Trauma

Mild repetitive traumatic brain injury (rTBI) induces chronic behavioral and cognitive alterations and increases the risk for dementia. Currently, there are no therapeutic strategies to prevent or mitigate chronic deficits associated with rTBI. Previously we developed an animal model of rTBI that recapitulates the cognitive and behavioral deficits observed in humans. We now report that rTBI results in an increase in risk-taking behavior in male but not female mice. This behavioral phenotype is associated with chronic activation of the integrated stress response and cell-specific synaptic alterations in the type A subtype of layer V pyramidal neurons in the medial prefrontal cortex. Strikingly, by briefly treating animals weeks after injury with ISRIB, a selective inhibitor of the integrated stress response (ISR), we (1) relieve ISR activation, (2) reverse the increased risk-taking behavioral phenotype and maintain this reversal, and (3) restore cell-specific synaptic function in the affected mice. Our results indicate that targeting the ISR even at late time points after injury can permanently reverse behavioral changes. As such, pharmacological inhibition of the ISR emerges as a promising avenue to combat rTBI-induced behavioral dysfunction.

Sex differences in steroid levels and steroidogenesis in the nervous system: Physiopathological role

The nervous system, in addition to be a target for steroid hormones, is the source of a variety of neuroactive steroids, which are synthesized and metabolized by neurons and glial cells. Recent evidence indicates that the expression of neurosteroidogenic proteins and enzymes and the levels of neuroactive steroids are different in the nervous system of males and females. We here summarized the state of the art of neuroactive steroids, particularly taking in consideration sex differences occurring in the synthesis and levels of these molecules. In addition, we discuss the consequences of sex differences in neurosteroidogenesis for the function of the nervous system under healthy and pathological conditions and the implications of neuroactive steroids and neurosteroidogenesis for the development of sex-specific therapeutic interventions.

Baseline Predictors of Survival, Neurological Recovery, Cognitive Function, Neuropsychiatric Outcomes, and Return to Work in Patients after a Severe Traumatic Brain Injury: an Updated Review

Introduction

Severe traumatic brain injury (sTBI) is a common cause of death and disability worldwide, with long-term squeal among survivors that include cognitive deficits, psychosocial and neuropsychiatric dysfunction, failure to return to pre-injury levels of work, school and inter-personal relationships, and overall reduced quality of and satisfaction with life.

Aim

The aim of this work is to review the current literature on baseline predictors of outcomes in adults post sTBI.

Method

Most of available literature on baseline predictors of outcomes in adults post sTBI were reviewed and summarized in this work.

Results

Currently, a sizeable number of composite predictors of mortality and overall function exists; however, these instruments tend to over-estimate poor outcomes and fail to address issues like cognition, psychosocial/ neuropsychiatric dysfunction, and return to work or school.

Conclusion

This article reviews currently-identified predictors of all these outcomes.

Age, education and gender effects on Wisconsin card sorting test: standardization, reliability and validity in healthy Argentinian adults

The Wisconsin Card Sorting Test (WCST) is a widely used neuropsychological assessment of executive functioning. The aim of this study was to provide norm values and analyze the psychometric properties of WCST in healthy Argentinian adults aged from 18 to 89 years old (N = 235). Descriptive statistics are reported as means, standard deviations and percentiles, with the effects of age, education and gender being investigated by ANOVA, and with the effect sizes being calculated. The psychometrics were studied using the WCST structure, reliability, convergent validity, and discriminant validity, and WCST norms adjusted for age and educational level are proposed. This instrument is a reliable and valid tool for the assessment of executive functions. However, as the age- and educational-related effects were demonstrated, these characteristics need to be considered before interpreting WCST scores. Regarding gender, no differences were found. Our results expand the geographical and sociocultural applicability of WCST.

Neurobehavioral Symptoms in Community-Dwelling Adults With and Without Chronic Traumatic Brain Injury: Differences by Age, Gender, Education, and Health Condition

Neurobehavioral symptoms after Traumatic Brain Injury (TBI) are prevalent, persist for many years, and negatively affect long-term health, function, and quality of life. Symptoms may differ based on age, gender, education, race, ethnicity, and injury severity. To better understand neurobehavioral functioning after TBI, we need a comprehensive picture of emotional, cognitive, and behavioral symptoms in the context of personal factors that may affect these symptoms. We also need to understand the extent to which these symptoms are specific to TBI, shared across other neurological conditions, or attributable to factors outside of the injury itself. We collected neurobehavioral symptoms via the self-reported Behavioral Assessment Screening Tool (BAST) in a National Cohort of English (n = 2,511) and Spanish speaking (n = 350) community-dwelling adults with and without chronic TBI and other neurological and mental health conditions. The primary focus of the present study was to comprehensively describe neurobehavioral symptoms in adults with and without TBI, broken down by gender and health conditions and then further by age group or educational attainment. As expected, participants with TBI reported more symptoms than Healthy Controls. Regardless of condition, women reported more fatigue, while men reported more substance abuse and impulsivity. Hispanic participants reported more neurobehavioral symptoms than non-Hispanic participants did across health conditions, though primarily Spanish-speakers reported fewer symptoms than English-speakers, suggesting that level of acculturation may contribute to symptom reporting. These data provide a comprehensive characterization of neurobehavioral symptoms in adults with TBI and adults without TBI (healthy controls, adults with other neurological conditions, and adults with mental health conditions).

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.

A Qualitative Study on the Transition Support Needs of Indigenous Australians Following Traumatic Brain Injury

Objective:

A growing body of qualitative literature globally describes post-hospital experiences during early recovery from a traumatic brain injury. For Indigenous Australians, however, little published information is available. This study aimed to understand the lived experiences of Indigenous Australians during the 6 months post-discharge, identify the help and supports accessed during transition and understand the gaps in service provision or difficulties experienced.

Methods and Procedure:

Semi-structured interviews were conducted at 6 months after hospital discharge to gain an understanding of the needs and lived experiences of 11 Aboriginal and Torres Strait Islander Australians who had suffered traumatic brain injury in Queensland and Northern Territory, Australia. Data were analysed using thematic analysis.

Results:

Five major themes were identified within the data. These were labelled ‘hospital experiences’, ‘engaging with medical and community-based supports’, ‘health and wellbeing impacts from the injury’, ‘everyday living’ and ‘family adjustments post-injury’.

Conclusions:

While some of the transition experiences for Indigenous Australians were similar to those found in other populations, the transition period for Indigenous Australians is influenced by additional factors in hospital and during their recovery process. Lack of meaningful interaction with treating clinicians in hospital, challenges managing direct contact with multiple service providers and the injury-related psychological impacts are some of the factors that could prevent Indigenous Australians from receiving the supports they require to achieve their best possible health outcomes in the long term. A holistic approach to care, with an individualised, coordinated transition support, may reduce the risks for re-admission with further head injuries.

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.

Neuroactive Steroids and Sex-Dimorphic Nervous Damage Induced by Diabetes Mellitus

Diabetes mellitus is a metabolic disease where improper glycaemic control may induce severe complications in different organs. In this review, we will discuss alterations occurring in peripheral and central nervous system of patients with type 1 (i.e., insulin dependent diabetes mellitus,) or type 2 diabetes (i.e., non-insulin dependent diabetes mellitus), as well as related experimental models. A particular focus will be on the role exerted by neuroactive steroids (i.e., important regulators of nervous functions) in the nervous damage induced by diabetes. Indeed, the nervous levels of these molecules are affected by the pathology and, in agreement, their neuroprotective effects have been reported. Interestingly, the sex is another important variable. As discussed, nervous diabetic complications show sex dimorphic features in term of incidence, functional outcomes and neuroactive steroid levels. Therefore, these features represent an interesting background for possible sex-oriented therapies with neuroactive steroids aimed to counteract nervous damage observed in diabetic pathology.

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.

Assessment of executive function using the Tinkertoy test

The Tinkertoy test (TTT) has often been used to assess executive function. Despite its clinical importance, there are few published normative data for it. Thus, the primary aim of this study was to fill this gap. Moreover, as there exists a sex difference in many cognitive abilities and neuropsychological tests, a secondary aim was to examine whether sex influences TTT performance. We administered the TTT to 25 healthy men and 25 healthy women whose average age was 28 years. Performances were scored based upon Lezak's (1982) original TTT criteria. On average, our participants used 43 pieces to complete their construction (SD=8), with a range of 21-50, and their complexity scores ranged from 7 to 12, with a mean score of 9.68 (SD=1.35). Overall performance did not differ based on sex; yet, when examining individual scoring criteria, we found that men scored significantly higher on the symmetry measure. Efforts towards the development of adequate normative data for the TTT and different tests of executive functioning are crucial to neuropsychologists' and other healthcare providers' ability to reliably diagnose and treat disorders of cognition that affect executive function. The present data go some way towards enhancing the utility of the TTT.

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.

Neuroactive steroids and diabetic complications in the nervous system

Important complications of diabetes mellitus in the nervous system are represented by diabetic peripheral neuropathy and diabetic encephalopathy. In this context, an important link is represented by neuroactive steroids (i.e., steroids coming from peripheral glands and affecting nervous functionality as well as directly synthesized in the nervous system). Indeed, diabetes does not only affect the reproductive axis and consequently the levels of sex steroid hormones, but also those of neuroactive steroids. Indeed, as will be here summarized, the levels of these neuromodulators present in the central and peripheral nervous system are affected by the pathology in a sex-dimorphic way. In addition, some of these neuroactive steroids, such as the metabolites of progesterone or testosterone, as well as pharmacological tools able to increase their levels have been demonstrated, in experimental models, to be promising protective agents against diabetic peripheral neuropathy and diabetic encephalopathy.

Traumatic Brain Injury and Post-Deployment Binge Drinking among Male and Female Army Active Duty Service Members Returning from Operation Enduring Freedom/Operation Iraqi Freedom

This study examines whether the relationship between traumatic brain injury (TBI) and post-deployment binge drinking is independent of screening positive for mental health problems among male and female service members. Data are from the Substance Use and Psychological Injury Combat Study of Army members returning from deployment to Afghanistan or Iraq in fiscal years 2008-2011. The sample consists of 240,694 male and 26,406 female active duty members who completed initial and follow-up questionnaires. The initial questionnaire, completed at the end of deployment, included screens for TBI and mental health problems (post-traumatic stress disorder, depression, harmful thoughts). The dependent variable, frequent binge drinking (six or more drinks on one occasion, at least monthly), was assessed on the follow-up questionnaire on average 3-9 months post-deployment. More than 21% of males and 7% of females reported frequent binge drinking. Male members were more likely to screen positive for TBI, compared with females (7.5% vs. 4.4%). Females with both TBI and mental health positive screens had more than double the risk of frequent binge drinking, compared with those without either problem (15.8% vs. 6.6%), and males with both problems had almost double the risk, compared with males with neither problem (33.6% vs. 19.7%). In multivariable logistic regression models, having a TBI and a comorbid positive mental health screen was associated with increased odds of frequent binge drinking among both males and females (adjusted odds ratio [AOR] = 1.59, CI: 1.50-1.69, and AOR = 2.11, CI: 1.57-2.83, respectively), compared with those with neither condition. More research is needed on the interaction of gender and binge drinking, especially when TBI and mental health problems co-exist.

Sex-Specific Predictors of Inpatient Rehabilitation Outcomes After Traumatic Brain Injury

OBJECTIVE

To identify sex-specific predictors of inpatient rehabilitation outcomes among patients with a traumatic brain injury (TBI) from a population-based perspective.

DESIGN

Retrospective cohort study.

SETTING

Inpatient rehabilitation.

PARTICIPANTS

Patients in inpatient rehabilitation for a TBI within 1 year of acute care discharge between 2008/2009 and 2011/2012 (N=1730, 70% men, 30% women).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Inpatient rehabilitation length of stay, total FIM score, and motor and cognitive FIM ratings at discharge.

RESULTS

Sex, as a covariate in multivariable linear regression models, was not a significant predictor of rehabilitation outcomes. Although many of the predictors examined were similar across men and women, sex-specific multivariable models identified some predictors of rehabilitation outcome that are specific for men and women; mechanism of injury (P<.0001) was a significant predictor of functional outcome only among women, whereas comorbidities (P<.0001) was a significant predictor for men only.

CONCLUSIONS

Predictors of outcomes after inpatient rehabilitation differed by sex, providing evidence for a sex-specific approach in planning and resource allocation for inpatient rehabilitation services for patients with TBI.

New steps forward in the neuroactive steroid field

Evidence accumulated in recent years suggests that the systemic treatment with neuroactive steroids, or the pharmacological modulation of its production by brain cells, represent therapeutic options to promote neuroprotection. However, new findings, which are reviewed in this paper, suggest that the factors to be considered for the design of possible therapies based on neuroactive steroids are more complex than previously thought. Thus, although as recently reported, the nervous system regulates neuroactive steroid synthesis and metabolism in adaptation to modifications in peripheral steroidogenesis, the neuroactive steroid levels in the brain do not fully reflect its levels in plasma. Even, in some cases, neuroactive steroid level modifications occurring in the nervous tissues, under physiological and pathological conditions, are in the opposite direction than in the periphery. This suggests that the systemic treatment with these molecules may have unexpected outcomes on neural steroid levels. In addition, the multiple metabolic pathways and signaling mechanisms of neuroactive steroids, which may change from one brain region to another, together with the existence of regional and sex differences in its neural levels are additional sources of complexity that should be clarified. This complexity in the levels and actions of these molecules may explain why in some cases these molecules have detrimental rather than beneficial actions for the nervous system. This article is part of a Special Issue entitled 'Steroid Perspectives'.

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.

Cognitive and psychological flexibility after a traumatic brain injury and the implications for treatment in acceptance-based therapies: A conceptual review

This paper provides a selective review of cognitive and psychological flexibility in the context of treatment for psychological distress after traumatic brain injury, with a focus on acceptance-based therapies. Cognitive flexibility is a component of executive function that is referred to mostly in the context of neuropsychological research and practice. Psychological flexibility, from a clinical psychology perspective, is linked to health and well-being and is an identified treatment outcome for therapies such as acceptance and commitment therapy (ACT). There are a number of overlaps between the constructs. They both manifest in the ability to change behaviour (either a thought or an action) in response to environmental change, with similarities in neural substrate and mental processes. Impairments in both show a strong association with psychopathology. People with a traumatic brain injury (TBI) often suffer impairments in their cognitive flexibility as a result of damage to areas controlling executive processes but have a positive response to therapies that promote psychological flexibility. Overall, psychological flexibility appears a more overarching construct and cognitive flexibility may be a subcomponent of it but not necessarily a pre-requisite. Further research into therapies which claim to improve psychological flexibility, such as ACT, needs to be undertaken in TBI populations in order to clarify its utility in this group.

Effects of defeat stress on behavioral flexibility in males and females: modulation by the mu-opioid receptor

Behavioral flexibility is a component of executive functioning that allows individuals to adapt to changing environmental conditions. Independent lines of research indicate that the mu opioid receptor (MOR) is an important mediator of behavioral flexibility and responses to psychosocial stress. The current study bridges these two lines of research and tests the extent to which social defeat and MOR affect behavioral flexibility and whether sex moderates these effects in California mice (Peromyscus californicus). Males and females assigned to social defeat or control conditions were tested in a Barnes maze. In males, defeat impaired behavioral flexibility but not acquisition. Female performance was unaffected by defeat. MOR binding in defeated and control mice in the orbitofrontal cortex (OFC), striatum and hippocampus was examined via autoradiography. Stressed males had reduced MOR binding in the OFC whereas females were unaffected. The MOR antagonist beta-funaltrexamine (1 mg/kg) impaired performance in males naïve to defeat during the reversal phase but had no effect on females. Finally, we examined the effects of the MOR agonist morphine (2.5 and 5 mg/kg) on stressed mice. As expected, morphine improved behavioral flexibility in stressed males. The stress-induced deficits in behavioral flexibility in males are consistent with a proactive coping strategy, including previous observations that stressed male California mice exhibit strong social approach and aggression. Our pharmacological data suggest that a down-regulation of MOR signaling in males may contribute to sex differences in behavioral flexibility following stress. This is discussed in the framework of coping strategies for individuals with mood disorders.

Gender-specific issues in traumatic injury and resuscitation: consensus-based recommendations for future research

Traumatic injury remains an unacceptably high contributor to morbidity and mortality rates across the United States. Gender-specific research in trauma and emergency resuscitation has become a rising priority. In concert with the 2014 Academic Emergency Medicine consensus conference "Gender-specific Research in Emergency Care: Investigate, Understand, and Translate How Gender Affects Patient Outcomes," a consensus-building group consisting of experts in emergency medicine, critical care, traumatology, anesthesiology, and public health convened to generate research recommendations and priority questions to be answered and thus move the field forward. Nominal group technique was used for the consensus-building process and a combination of face-to-face meetings, monthly conference calls, e-mail discussions, and preconference surveys were used to refine the research questions. The resulting research agenda focuses on opportunities to improve patient outcomes by expanding research in sex- and gender-specific emergency care in the field of traumatic injury and resuscitation.

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.

Outcome in Women with Traumatic Brain Injury Admitted to a Level 1 Trauma Center

Background. The aim of this study was to compare acute outcome between men and women after sustaining a traumatic brain injury (TBI). Methods. A total of 5,642 patients admitted to the Traumatic Brain Injury Program of the McGill University Health Centre-Montreal General Hospital between 2000 and 2011 and diagnosed with a TBI were included in the study. The overall percentage of women with TBI was 30.6% (n = 1728). Outcome measures included the length of stay (LOS), the Extended Glasgow Outcome Scale (GOSE), the functional independence measure instrument (FIM), discharge destination, and mortality rate. Results. LOS, GOSE, the FIM ratings, and discharge destination did not show significant differences between genders once controlling for several confounding variables and running the appropriate diagnostic tests (P < 0.05). However, women had less chance of dying during their acute care hospitalization than men of the same age, with the same TBI severity and following the same mechanism of injury. Although gender was a statistically significant predictor, its contribution in explaining variation in mortality was small. Conclusion. More research is needed to better understand gender differences in mortality; as to date, the research findings remain inconclusive.

Gender differences in awareness and outcomes during acute traumatic brain injury recovery

BACKGROUND

Recent literature on traumatic brain injury (TBI), though mixed when reporting outcomes, seems collectively to suggest possible gender advantage for women in postinjury recovery, especially in executive functions. Hormonal neuroprotection, through female reproductive hormones, is often proposed as an underlying factor in these results. We explored potential gender differences in an aspect of executive functions, self-awareness (SA), which is often impaired after TBI, limits patient effort in critical rehabilitation, and increases caregiver burden.

METHODS

Within a prospective survey, repeated-measures design, 121 patients with moderate or severe TBI undergoing acute rehabilitation in a Level 1 trauma center, a family member or caregiver informant, and a treating clinician were asked to complete the Patient Competency Rating Scale (PCRS) and the Frontal Systems Behavior Scale (FrSBe) at admission and discharge.

RESULTS

Although overall, women and men with TBI showed generally similar levels of SA, women had significantly better awareness of their injury-related deficits at acute rehabilitation discharge, even when controlling for age, education, and injury severity.

CONCLUSIONS

Mixed findings in this study mirror the pattern of results that dominate the published literature on gender and TBI. Gender differences in executive dysfunction may not be as large or robust as some researchers argue. In addition, complex interplays of socialization, gender-role expectations, naturally occurring male and female ability differences, and differences in access to postinjury rehabilitation are understudied potential moderators.

The effects of sleep on the relationship between brain injury severity and recovery of cognitive function: a prospective study

BACKGROUND

Disturbed sleep pattern is a common symptom after head trauma and its prevalence in acute traumatic brain injury (TBI) is less discussed. Sleep has a profound impact on cognitive function recovery and the mediating effect of disturbed sleep on cognitive function recovery has not been examined after acute TBI.

OBJECTIVES

To identify the prevalence of disturbed sleep in mild, moderate, and severe acute TBI patients, and to determine the mediating effects of sleep on the relationship between brain injury severity and the recovery of cognitive function.

DESIGN

A prospective study design.

SETTING

Neurosurgical wards in a medical center in northern Taiwan.

PARTICIPANTS

Fifty-two acute TBI patients between the ages of 18 and 65 years who had received a diagnosis of TBI for the first time, and were admitted to the neurosurgical ward.

METHOD

The severity of brain injury was initially determined using the Glasgow Coma Scale. Each patient wore an actigraphy instrument on a non-paralytic or non-dominated limb for 7 consecutive days. A 7-day sleep diary was used to facilitate data analysis. Cognitive function was assessed on the first and seventh day after admission based on the Rancho Los Amigos Levels of Cognitive Functioning.

RESULTS

The mild (n=35), moderate (n=7) and severe (n=10) TBI patients exhibited poorer sleep efficiency, and longer total sleep time (TST) and waking time after sleep onset, compared with the normative values for the sleep-related variables (P<.05 for all). The severe and moderate TBI patients had longer daytime TST than the mild TBI patients (P<.001), and the severe TBI patients had longer 24-h TST than the mild TBI patients (P=.001). The relationship between the severity of brain injury and the recovery of cognition function was mediated by daytime TST (t=-2.65, P=.004).

CONCLUSIONS

Poor sleep efficiency, prolonged periods of daytime sleep, and a high prevalence of hypersomnia are common symptoms in acute TBI patients. The duration of daytime sleep mediates the relationship between the severity of brain injury and the recovery of cognition function.

Are there cognitive and neurobehavioural correlates of hormonal neuroprotection for women after TBI?

This study examined possible cognitive correlates of hormonal neuroprotection following traumatic brain injury (TBI) using archival neuropsychological findings for 1563 individuals undergoing acute TBI rehabilitation between 1989 and 2002. Presumed age of menopause was based on the STRAW (Stages of Reproductive Aging) staging system (Soules, 2005; Soules et al., 2001) and general linear model (GLM) analysis of performance on neuropsychological testing by participants across gender and age groups (25-34, 35-44, 45-54, and 55-64) was performed. Hypotheses were (1) women with TBI in the oldest age group would have lower scores on neuropsychological tests and functional outcome measures than women in the younger groups, and (2) men in the oldest age group would have higher scores than women of the same age group. Analyses revealed that oldest females had significantly worse Trails B and SDMT written and oral scores than the youngest females. In addition, oldest females had significantly better Trails B, Rey AVLT and SDMT written scores than the oldest males. Possible cohort exposure to hormone replacement therapy, unknown hormonal status at time of testing, and sample-specific injury characteristics may have contributed to these findings.