A population-based study of repetitive traumatic brain injury among persons with traumatic brain injury

Sex-dependent perturbations in risky choice behavior and prefrontal tyrosine hydroxylase levels induced by repetitive mild traumatic brain injury

Head trauma often impairs cognitive processes mediated within the prefrontal cortex (PFC), leading to impaired decision making and risk-taking behavior. Mild traumatic brain injury (mTBI) accounts for approximately 80 % of reported head injury cases. Most neurological symptoms of a single mTBI are transient; however, growing evidence suggests that repeated mTBI (rmTBI) results in more severe impairments that worsen with each subsequent injury. Although mTBI-induced disruption of risk/reward decision making has been characterized, the potential for rmTBI to exacerbate these effects and the neural mechanisms involved are unknown. Catecholamine neurotransmitters, dopamine (DA) and norepinephrine (NE), modulate PFC-mediated functions. Imbalances in catecholamine function have been associated with TBI and may underlie aberrant decision making. We used a closed head-controlled cortical impact (CH-CCI) model in rats to evaluate the effects of rmTBI on performance of a probabilistic discounting task of risk/reward decision making behavior and expression levels of catecholamine regulatory proteins within the PFC. RmTBI produced transient increases in risky choice preference in both male and female rats, with these effects persisting longer in females. Additionally, rmTBI increased expression of the catecholamine synthetic enzyme, tyrosine hydroxylase (TH), within the orbitofrontal (OFC) region of the PFC in females only. These results suggest females are more susceptible to rmTBI-induced disruption of risk/reward decision making behavior and dysregulation of catecholamine synthesis within the OFC. Together, using the CH-CCI model of rodent rmTBI to evaluate the effects of multiple insults on risk-taking behavior and PFC catecholamine regulation begins to differentiate how mTBI occurrences affect neuropathological outcomes across different sexes.

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

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

Longitudinal Recovery Following Repetitive Traumatic Brain Injury

Importance

One traumatic brain injury (TBI) increases the risk of subsequent TBIs. Research on longitudinal outcomes of civilian repetitive TBIs is limited.

Objective

To investigate associations between sustaining 1 or more TBIs (ie, postindex TBIs) after study enrollment (ie, index TBIs) and multidimensional outcomes at 1 year and 3 to 7 years.

Design, Setting, and Participants

This cohort study included participants presenting to emergency departments enrolled within 24 hours of TBI in the prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study (enrollment years, February 2014 to July 2020). Participants who completed outcome assessments at 1 year and 3 to 7 years were included. Data were analyzed from September 2022 to August 2023.

Exposures

Postindex TBI(s).

Main Outcomes and Measures

Demographic and clinical factors, prior TBI (ie, preindex TBI), and functional (Glasgow Outcome Scale-Extended [GOSE]), postconcussive (Rivermead Post-Concussion Symptoms Questionnaire [RPQ]), psychological distress (Brief Symptom Inventory-18 [BSI-18]), depressive (Patient Health Questionnaire-9 [PHQ-9]), posttraumatic stress disorder (PTSD; PTSD Checklist for DSM-5 [PCL-5]), and health-related quality-of-life (Quality of Life After Brain Injury-Overall Scale [QOLIBRI-OS]) outcomes were assessed. Adjusted mean differences (aMDs) and adjusted relative risks are reported with 95% CIs.

Results

Of 2417 TRACK-TBI participants, 1572 completed the outcomes assessment at 1 year (1049 [66.7%] male; mean [SD] age, 41.6 [17.5] years) and 1084 completed the outcomes assessment at 3 to 7 years (714 [65.9%] male; mean [SD] age, 40.6 [17.0] years). At 1 year, a total of 60 participants (4%) were Asian, 255 (16%) were Black, 1213 (77%) were White, 39 (2%) were another race, and 5 (0.3%) had unknown race. At 3 to 7 years, 39 (4%) were Asian, 149 (14%) were Black, 868 (80%) were White, 26 (2%) had another race, and 2 (0.2%) had unknown race. A total of 50 (3.2%) and 132 (12.2%) reported 1 or more postindex TBIs at 1 year and 3 to 7 years, respectively. Risk factors for postindex TBI were psychiatric history, preindex TBI, and extracranial injury severity. At 1 year, compared with those without postindex TBI, participants with postindex TBI had worse functional recovery (GOSE score of 8: adjusted relative risk, 0.57; 95% CI, 0.34-0.96) and health-related quality of life (QOLIBRI-OS: aMD, -15.9; 95% CI, -22.6 to -9.1), and greater postconcussive symptoms (RPQ: aMD, 8.1; 95% CI, 4.2-11.9), psychological distress symptoms (BSI-18: aMD, 5.3; 95% CI, 2.1-8.6), depression symptoms (PHQ-9: aMD, 3.0; 95% CI, 1.5-4.4), and PTSD symptoms (PCL-5: aMD, 7.8; 95% CI, 3.2-12.4). At 3 to 7 years, these associations remained statistically significant. Multiple (2 or more) postindex TBIs were associated with poorer outcomes across all domains.

Conclusions and Relevance

In this cohort study of patients with acute TBI, postindex TBI was associated with worse symptomatology across outcome domains at 1 year and 3 to 7 years postinjury, and there was a dose-dependent response with multiple postindex TBIs. These results underscore the critical need to provide TBI prevention, education, counseling, and follow-up care to at-risk patients.

Sports-Related Concussions in Adults Presenting to Canadian Emergency Departments

OBJECTIVE

To document the occurrence and recovery outcomes of sports-related concussions (SRCs) presenting to the Emergency Department (ED) in a community-based sample.

DESIGN

A prospective observational cohort study was conducted in 3 Canadian hospitals.

SETTING

Emergency Department.

PATIENTS

Adults (≥17 years) presenting with a concussion to participating EDs with a Glasgow Coma Scale score ≥13 were recruited.

INTERVENTIONS

Patient demographics (eg, age and sex), clinical characteristics (eg, history of depression or anxiety), injury characteristics (eg, injury mechanisms and loss of consciousness and duration), and ED management and outcomes (eg, imaging, consultations, and ED length of stay) were collected.

MAIN OUTCOME MEASURES

Patients' self-reported persistent concussion symptoms, return to physical activity status, and health-related quality of life at 30 and 90 days after ED discharge.

RESULTS

Overall, 248 patients were enrolled, and 25% had a SRC. Patients with SRCs were younger and reported more physical activity before the event. Although most of the patients with SRCs returned to their normal physical activities at 30 days, postconcussive symptoms persisted in 40% at 90 days of follow-up. After adjustment, there was no significant association between SRCs and persistent symptoms; however, patients with concussion from motor vehicle collisions were more likely to have persistent symptoms.

CONCLUSION

Although physically active individuals may recover faster after a concussion, patients returning to their physical activities before full resolution of symptoms are at higher risk of persistent symptoms and further injury. Patient-clinician communications and tailored recommendations should be encouraged to guide appropriate acute management of concussions.

Repetitive Traumatic Brain Injury Among Older Adults

OBJECTIVE

To determine the incidence of and assess risk factors for repetitive traumatic brain injury (TBI) among older adults in the United States.

DESIGN

Retrospective cohort study.

SETTING

Administrative claims data obtained from the Centers for Medicare & Medicaid Services' Chronic Conditions Data Warehouse.

PARTICIPANTS

Individuals 65 years or older and diagnosed with TBI between July 2008 and September 2012 drawn from a 5% random sample of US Medicare beneficiaries.

MAIN MEASURES

Repetitive TBI was identified as a second TBI occurring at least 90 days after the first occurrence of TBI following an 18-month TBI-free period. We identified factors associated with repetitive TBI using a log-binomial model.

RESULTS

A total of 38 064 older Medicare beneficiaries experienced a TBI. Of these, 4562 (12%) beneficiaries sustained at least one subsequent TBI over up to 5 years of follow-up. The unadjusted incidence rate of repetitive TBI was 3022 (95% CI, 2935-3111) per 100 000 person-years. Epilepsy was the strongest predictor of repetitive TBI (relative risk [RR] = 1.44; 95% CI, 1.25-1.56), followed by Alzheimer disease and related dementias (RR = 1.32; 95% CI 1.20-1.45), and depression (RR = 1.30; 95% CI, 1.21-1.38).

CONCLUSIONS

Injury prevention and fall-reduction interventions could be targeted to identify groups of older adults at an increased risk of repetitive head injury. Future work should focus on injury-reduction initiatives to reduce the risk of repetitive TBI as well as assessment of outcomes related to repetitive TBI.

Prevalence of Disability Associated With Head Injury With Loss of Consciousness in Adults in the United States: A Population-Based Study

OBJECTIVE

To provide nationally representative prevalence estimates of disability associated with prior head injury with loss of consciousness in the United States and to examine associations between prior head injury and disability.

METHODS

This was a cross-sectional analysis of 7,390 participants ≥40 years of age in the 2011-2014 National Health and Nutrition Examination Surveys (NHANES). Head injury with loss of consciousness was assessed by self-report. Domains of disability were assessed with a standardized structured questionnaire and measured grip strength. Logistic and linear regression models adjusted for demographic, socioeconomic/behavioral, and medical comorbidity variables were used. Multiple imputation was used to account for missing covariate data.

RESULTS

Mean age of participants was 58 years; 53% were female; 71% were non-Hispanic White; and 16% had a history of head injury with loss of consciousness. Overall, participants with a history of head injury had higher prevalence of disability in at least 1 domain of functioning compared to individuals without head injury (47.4% vs 38.6%, p < 0.001), with the highest prevalence of disability in the domains of mobility and work productivity. In fully adjusted models, head injury was significantly positively associated with disability in all domains assessed on the standardized questionnaire (all p < 0.05). Participants with head injury had greater grip strength (all p < 0.05).

CONCLUSIONS

We found that 47.4% of individuals ≥40 years of age in the United States with a history of head injury are living with disability in at least 1 domain of functioning, corresponding to 11.4 million affected individuals. This significant burden of disability suggests that efforts are needed to improve functioning among individuals with head injury.

Recurrent Traumatic Brain Injury Surveillance Using Administrative Health Data: A Bayesian Latent Class Analysis

Background: The initial injury burden from incident TBI is significantly amplified by recurrent TBI (rTBI). Unfortunately, research assessing the accuracy to conduct rTBI surveillance is not available. Accurate surveillance information on recurrent injuries is needed to justify the allocation of resources to rTBI prevention and to conduct high quality epidemiological research on interventions that mitigate this injury burden. This study evaluates the accuracy of administrative health data (AHD) surveillance case definitions for rTBI and estimates the 1-year rTBI incidence adjusted for measurement error. Methods: A 25% random sample of AHD for Montreal residents from 2000 to 2014 was used in this study. Four widely used TBI surveillance case definitions, based on the International Classification of Disease and on radiological exams of the head, were applied to ascertain suspected rTBI cases. Bayesian latent class models were used to estimate the accuracy of each case definition and the 1-year rTBI measurement-error-adjusted incidence without relying on a gold standard rTBI definition that does not exist, across children (<18 years), adults (18-64 years), and elderly (> =65 years). Results: The adjusted 1-year rTBI incidence was 4.48 (95% CrI 3.42, 6.20) per 100 person-years across all age groups, as opposed to a crude estimate of 8.03 (95% CrI 7.86, 8.21) per 100 person-years. Patients with higher severity index TBI had a significantly higher incidence of rTBI compared to patients with lower severity index TBI. The case definition that identified patients undergoing a radiological examination of the head in the context of any traumatic injury was the most sensitive across children [0.46 (95% CrI 0.33, 0.61)], adults [0.79 (95% CrI 0.64, 0.94)], and elderly [0.87 (95% CrI 0.78, 0.95)]. The most specific case definition was the discharge abstract database in children [0.99 (95% CrI 0.99, 1.00)], and emergency room visits claims in adults/elderly [0.99 (95% CrI 0.99, 0.99)]. Median time to rTBI was the shortest in adults (75 days) and the longest in children (120 days). Conclusion: Conducting accurate surveillance and valid epidemiological research for rTBI using AHD is feasible when measurement error is accounted for.

Estimating Repeat Traumatic Brain Injury in the U.S. Military, 2015-2017

INTRODUCTION

Traumatic brain injury (TBI) is a significant health issue among deployed and non-deployed U.S. military service members (SMs). Since 2000, an estimated 413,858 SMs have been diagnosed with at least one TBI. Due to the difficulty in distinguishing new incident TBIs from follow-up TBI-related medical encounters in the Military Health System (MHS), the official TBI case definition also includes an incidence rule considering an individual an incident case only once per lifetime. We sought to examine patterns in medical records of SMs with at least one TBI encounter, in an effort to identify repeat TBIs in individual SMs and to estimate the incidence of repeat TBIs within the study cohort as a whole.

MATERIALS AND METHODS

Using the official DoD TBI case definition, we obtained a list of SMs who sustained their first active duty TBI between October 1, 2015, and September 30, 2017. We identified the SM's diagnosing encounter (index TBI). Subsequently, we identified patterns associated with diagnosing medical encounters, as opposed to encounters associated with follow-up TBI care. We flagged external cause of injury records and the presence of TBI-related symptom codes at the diagnosing encounter. Traumatic brain injury-related symptoms included memory issues, alteration of cognition, hearing loss, vertigo, headache, anxiety, depression, emotional lability, weakness, insomnia, and vision disturbance. Data discovery results were shared with a group of clinicians at the Defense and Veterans Brain Injury Center, and the list of variables was further refined based on clinical expertise. Subsequently, we conducted stepwise logistic regression, and best fitting model was used to create a probability score to be applied to all TBI-related medical encounters. To validate the accuracy of the model-derived probability score, a stratified random sample of medical records was reviewed by trained clinician. At the 0.5 probability cutoff point, the model had an area under the curve of 0.69. We applied the final model portability scores to all identified TBI encounters to estimate the incidence of repeat TBI within the cohort.

RESULTS

Between October 1, 2015, and September 30, 2017, we identified 36,440 SMs and their first lifetime TBI encounter. Study follow-up period was 2 years. Predictors of repeat TBI (rTBI) encounters included the presence of TBI diagnosis extender codes "A" (odds ratio [OR] = 4.67, 95% CI 2.15-10.12); W and V series codes (OR = 4.05, 95% CI 2.05-7.95 and OR = 2.86, 95% CI 1.40-5.83, respectively); patient's disposition at home/quarters; and admission or immediate referral (OR = 3.67, 95% CI 1.79-7.51). Number of diagnosis codes in patient's medical record was inversely associated with a repeat TBI encounter (OR = 0.84, 95% CI 0.76-0.96). Applying model-derived probability score onto identified medical records, we estimate that 804 unique SMs sustained an rTBI during the follow-up period, yielding a rate of 260 rTBIs per 10,000 person-years or approximately 2.32% of SMs annually.

CONCLUSION

Probability scores based on statistical modeling can provide reasonable estimates of repeat incidences of TBI using medical billing data when formerly only the first TBI was thought to be measurable. With 100% sensitivity and 69% specificity, application of these models can inform estimates of repeat TBI across the MHS. This effort shows initial success if estimating repeat TBI, and further modeling work is encouraged to increase the predictive characteristics of the models as these efforts show promise in estimating repeat TBI across the MHS.

Reinjury After Moderate to Severe TBI: Rates and Risk Factors in the NIDILRR Traumatic Brain Injury Model Systems

OBJECTIVES

To compare characteristics of those who do and do not sustain subsequent traumatic brain injuries (TBIs) following index TBI and to identify reinjury risk factors.

DESIGN

Secondary data analysis of an ongoing longitudinal cohort study.

SETTING

TBI Model Systems Centers.

PARTICIPANTS

In total, 11 353 individuals aged 16+ years.

MAIN OUTCOME MEASURES

Ohio State University TBI Identification Method.

RESULTS

In total, 7.9% of individuals reported sustaining a TBI post-index TBI. Twenty percent of reinjuries occurred within a year of the index TBI. Reinjury risk followed an approximate U-shaped distribution such that risk was higher in the first year, declined 2 to 10 years postinjury, and then increased after 10 years. A multivariable Weibull model identified predictors of reinjury: younger (<29 years) and middle-aged and older (50+ years) age at index TBI relative to middle age, pre-index TBI, pre-index alcohol and illicit drug use, incarceration history, and less severe index TBI.

CONCLUSIONS

A subset of individuals who receive inpatient rehabilitation for TBI are at an increased risk for reinjury, and an injury-prone phenotype may be characterized by engagement in risk behaviors. Factors associated with reinjury risk may differ for younger versus middle-aged and older adults. Findings underscore the need for empirically informed risk stratification models to identify TBI survivors at risk for reinjury.

Association of race and ethnicity to incident epilepsy, or epileptogenesis, after subdural hematoma

OBJECTIVE

To determine whether race is associated with the development of epilepsy after subdural hematoma (SDH), we identified adult survivors of SDH in a statewide administrative dataset and followed them up for at least 1 year for revisits associated with epilepsy.

METHODS

We performed a retrospective cohort study using claims data on all discharges from emergency departments (EDs) and hospitals in California. We identified adults (age ≥18 years) admitted from 2005 to 2011 with first-time traumatic and nontraumatic SDH. We used validated diagnosis codes to identify a primary outcome of ED or inpatient revisit for epilepsy. We used multivariable Cox regression for survival analysis to identify demographic and medical risk factors for epilepsy.

RESULTS

We identified 29,342 survivors of SDH (mean age 71.2 [SD 16.4] years, female sex 11,954 [41.1%]). Three thousand two hundred thirty (11.0%) patients had revisits to EDs or hospitals with a diagnosis of epilepsy during the study period. Black patients (n = 1,684 [5.7%]) had significantly increased risk compared to White patients (n = 16,945 [57.7%]; hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.28-1.64, p < 0.001). Status epilepticus during the index SDH admission, although infrequent (n = 94 [0.3%]), was associated with a nearly 4-fold risk of epilepsy (HR 3.75, 95% CI 2.80-5.03, p < 0.001). Alcohol use, drug use, smoking, renal disease, and markers of injury severity (i.e., intubation, surgical intervention, length of stay, disposition other than home) were also associated with epilepsy (all p < 0.05).

CONCLUSIONS

We found an association between Black race and ED and hospital revisits for epilepsy after SDH, establishing the presence of a racial subgroup that is particularly vulnerable to post-SDH epileptogenesis.

Injuries to the Head and Face From Skateboarding: A 10-Year Analysis From National Electronic Injury Surveillance System Hospitals

PURPOSE

To estimate the incidence of patients presenting to emergency departments (EDs) as a result of facial trauma sustained from skateboarding.

PATIENTS AND METHODS

The National Electronic Injury Surveillance System (NEISS) database was queried for skateboard-related head and face fractures, contusions, abrasions, and lacerations from 2009 through 2018. We identified 2,519 reported injuries, extrapolating to a national incidence of 100,201 injuries. Fractures accounted for 14.1% of these visits. There were 355 ED visits for fractures, extrapolating to an estimated 11,893 visits nationally. Entries were tabulated for demographic information, fracture type, mechanism of injury, and disposition.

RESULTS

Patients sustaining injury to the head and face were aged 16 years, on average, and predominantly male patients (85.9%). Most patients sustaining fractures were male patients (87.9%), with a mean age of 18 years. The most common fracture types included unspecified skull fractures (31%), nasal fractures (29%), and mandibular fractures (18%). The most common mechanism of injury was falling off the skateboard while riding (76.9%). Collisions with motor vehicles also accounted for a substantial proportion of the injuries (7.3%).

CONCLUSIONS

A substantial number of ED visits were a result of skateboarding-related facial trauma. Given the neurologic outcomes of head trauma and functional consequences of facial fractures, especially among adolescents, our findings suggest that injury prevention programs and more aggressive helmet use may be necessary to reduce morbidity and hospitalization.

Modelling seizure rates rather than time to an event within clinical trials of antiepileptic drugs

BACKGROUND

Predictive models within epilepsy are frequently developed via Cox's proportional hazards models. These models estimate risk of a specified event such as 12-month remission. They are relatively simple to produce, have familiar output, and are useful to answer questions about short-term prognosis. However, the Cox model only considers time to first event rather than all seizures after starting treatment for example. This makes assessing change in seizure rates over time difficult. Variants to the Cox model exist enabling recurrent events to be modelled. One such variant is the Prentice, Williams and Peterson - Total Time (PWP-TT) model. An alternative is the negative binomial model for event counts. This study aims to demonstrate the differences between the three approaches, and to consider the benefits of the PWP-TT approach for assessing change in seizure rates over time.

METHODS

Time to 12-month remission and time to first seizure after randomisation were modelled using the Cox model. Risk of seizure recurrence was modelled using the PWP-TT model, including all seizures across the whole follow-up period. Seizure counts were modelled using negative binomial regression. Differences between the approaches were demonstrated using participants recruited to the UK-based multi-centre Standard versus New Antiepileptic Drug (SANAD) study.

RESULTS

Results from the PWP-TT model were similar to those from the conventional Cox and negative binomial models. In general, the direction of effect was consistent although the variables included in the models and the significance of the predictors varied. The confidence intervals obtained via the PWP-TT model tended to be narrower due to the increase in statistical power of the model.

CONCLUSIONS

The Cox model is useful for determining the initial response to treatment and potentially informing when the next intervention may be required. The negative binomial model is useful for modelling event counts. The PWP-TT model extends the Cox model to all included events. This is useful in determining the longer-term effects of treatment policy. Such a model should be considered when designing future clinical trials in medical conditions typified by recurrent events to improve efficiency and statistical power as well as providing evidence regarding changes in event rates over time.

Influence of Prior and Intercurrent Brain Injury on 5-Year Outcome Trajectories After Moderate to Severe Traumatic Brain Injury

OBJECTIVE

To characterize the influence of additional (both prior and subsequent) traumatic brain injuries (TBIs) on recovery after a moderate to severe index TBI.

SETTING

Traumatic Brain Injury Model Systems centers.

PARTICIPANTS

Persons with moderate to severe TBI (N = 5054) enrolled in the TBI Model Systems National Database with complete outcome data for the outcomes of interest at 1-, 2-, and 5-year follow-up.

DESIGN

Secondary analysis of a prospective longitudinal data set.

MAIN MEASURES

Prior and intercurrent TBI from the Ohio State University TBI Identification Method (OSU TBI-ID), Disability Rating Scale (DRS), and Functional Independence Measure (FIM).

RESULTS

Prior moderate-severe TBIs significantly predicted overall level of functioning on the DRS, FIM Cognitive, and FIM Motor for participants with less severe index injuries. Moderate-severe intercurrent TBIs (TBIs subsequent to the index injury) were predictive of poorer functioning for both Index Severity groups, reflected in higher mean scores on the DRS in participants with less severe index injuries and lower mean Cognitive FIM in participants with more severe index injuries.

CONCLUSION

Multiple brain injuries, particularly those of moderate or greater severity, have a significantly greater impact on patients' level of functioning compared with a single injury, but not the rate or shape of recovery.

A Prospective Study of Childhood Predictors of Traumatic Brain Injuries Sustained in Adolescence and Adulthood

OBJECTIVE

Traumatic brain injuries (TBIs) are sustained by approximately 17% of males in the general population, many of whom subsequently present mental disorders, cognitive, and physical problems. Little is known about predictors of TBIs and how to prevent them. The present study aimed to determine whether inattention-hyperactivity and/or all externalizing problems presented by boys at age 10 predict subsequent TBIs to age 34 after taking account of previous TBIs and family social status (FSS).

METHOD

742 Canadian males were followed, prospectively, from age 6 to 34. Diagnoses of TBIs were extracted from health files, parents-reported sociodemographic and family characteristics at participants' age 6, and teachers-rated participants' behaviors at age 10. Separate logistic regression models predicted TBIs sustained from age 11 to 17 and from age 18 to 34. For each age period, two models were computed, one included previous TBIs, inattention-hyperactivity, FSS, and interaction terms, the second included previous TBIs, externalizing problems, FSS, and interaction terms.

RESULTS

In models that included inattention-hyperactivity, TBIs sustained from age 11 to 17 were predicted by age 10 inattention-hyperactivity (odds ratio [OR] = 1.46, 1.05 to 2.05) and by TBIs prior to age 11 (OR = 3.50, 1.48 to 8.24); TBIs sustained from age 18 to 34 were predicted by age 10 inattention-hyperactivity (OR = 1.31, 1.01 to 170). In models that included all externalizing problems, TBIs from age 11 to 17 were predicted by prior TBIs (OR = 3.66, 1.51 to 8.39); TBIs sustained from age 18 to 34 were predicted by age 10 externalizing problems (OR = 1.45, 1.12 to 1.86). Neither FSS nor interaction terms predicted TBIs in any of the models.

CONCLUSIONS

Among males, using evidence-based treatments to reduce inattention-hyperactivity and externalizing problems among boys could, potentially, decrease the risk of TBIs to age 34. Further, boys who sustain TBIs in childhood require monitoring to prevent recurrence in adolescence.

Women in Prison With Traumatic Brain Injury: Prevalence, Mechanism, and Impact on Mental Health

Relatively little is known about the characteristics of female offenders. Here, we studied the prevalence of traumatic brain injury (TBI) and mental health issues in an exclusively female prison population in New Zealand. Participants ( N = 38) were recruited from all security levels at Christchurch Women's Prison. Measures for depression, anxiety, and stress, sleep, and a history of TBI were administered; 94.7% (36/38) of participants presented with a history of TBI. Younger age at first injury was associated with an increased risk of mental health problems. The study concludes that TBI is highly prevalent among female offenders and may be linked to increased mental health problems. TBI should be considered as an important factor in offender pathways and treatment programs.

Risk factors for recurrent neurotrauma: a population-based study in Southeastern Michigan

INTRODUCTION

Studies have shown an increased risk of traumatic brain injury (TBI) for individuals who suffer an initial TBI. The current study hypothesized that individuals with recurrent neurotrauma would originate from populations considered 'vulnerable', i.e. low income and/or with psychiatric comorbidities.

METHODS

Data from the Michigan State Inpatient Database from 2006 to 2014 for the Detroit metropolitan area enlisted a study population of 50 744 patients with neurotrauma. Binary logistic regression was used to assess risk factors associated with admission for subsequent neurotrauma compared with single neurotrauma admission.

RESULTS

Patients with repeated neurotrauma admissions were similar to those with one-time trauma in terms of age at first admission and neighbourhood income levels. However, patients with repeated neurotrauma admissions were more likely to be male (p < .001) and African-American (p < .001). Comorbid alcohol use and drug use were 39% and 15% less likely to be readmitted with neurotrauma, respectively. Comorbid conditions associated with greater risk of repeat neurotrauma included depression, psychosis, and neurological disorders, increasing risk by 38%, 22%, and 58%, respectively.

CONCLUSION

This study validated the hypothesis that comorbid psychiatric conditions are a significant risk factor for recurrent neurotrauma and validate prior studies showing gender and race as significant risk factors.

Traumatic Brain Injury, Sleep, and Mental Health: A Longitudinal Study of Air Force Personnel Pre- and Postdeployment to Iraq

OBJECTIVE

We investigated the complex relationships between traumatic brain injury (TBI), sleep, and mental health problems longitudinally among US service members (SMs) pre- and postdeployment to Iraq.

PARTICIPANTS

One hundred sixty-eight SMs enrolled in a 4-week Air Force Basic Combat Convoy Course predeployment.

DESIGN

Self-report data were collected at the beginning and end of training and then at 1, 3, 6, and 12 months postdeployment. Regression analyses were implemented, and participants were categorized into 4 groups based on TBI history for further statistical analysis.

RESULTS

Positive TBI history was associated with greater symptoms of insomnia and posttraumatic stress predeployment and persistence of insomnia symptoms, posttraumatic stress, and depression postdeployment. Positive TBI history and posttraumatic stress served as risk factors for head injury in Iraq, and SMs who reported a head injury during deployment also endorsed greater posttraumatic stress postdeployment than those without head injury. SMs with positive TBI history who also reported a new TBI in Iraq endorsed the greatest sleep and mental health problems across the study period.

CONCLUSIONS

This study provides valuable information regarding temporal relationships between TBI, sleep, and mental health problems among a combat military population. Findings have important implications from both prevention and clinical perspectives.

Epidemiology of recurrent traumatic brain injury in the general population: A systematic review

OBJECTIVE

To comprehensively assess recurrent traumatic brain injury (rTBI) risk and risk factors in the general population.

METHODS

We systematically searched MEDLINE, EMBASE, and the references of included studies until January 16, 2017, for general population observational studies reporting rTBI risk or risk factors. Estimates were not meta-analyzed due to significant methodologic heterogeneity between studies, which was evaluated using meta-regression.

RESULTS

Twenty-two studies reported recurrence risk and 11 reported on 27 potential risk factors. rTBI risk was heterogeneous and varied from 0.43% (95% confidence interval [CI] 0.19%-0.67%) to 41.92% (95% CI 34.43%-49.40%), with varying follow-up periods (3 days-55 years). Median time to recurrence ranged from 0.5 to 3.8 years. In studies where cases were ascertained from multiple points of care, at least 5.50% (95% CI 4.80%-6.30%) of patients experienced a recurrence after a 1-year follow-up. Studies that used administrative data/self-report surveys to ascertain cases tended to report higher risk. Risk factors measured at time of index traumatic brain injury (TBI) that were significantly associated with rTBI in more than one study were male sex, prior TBI before index case, moderate or severe TBI, and alcohol intoxication. Risk factors reported in a single study that were significantly associated with rTBI were epilepsy, not seeking medical care, and multiple factors indicative of low socioeconomic status.

CONCLUSIONS

rTBI is an important contributor to the general population TBI burden. Certain risk factors can help identify individuals at higher risk of these repeated injuries. However, higher quality research that improves on rTBI surveillance methodology is needed.

Incidence and risk factors of posttraumatic seizures following traumatic brain injury: A Traumatic Brain Injury Model Systems Study

OBJECTIVE

Determine incidence of posttraumatic seizure (PTS) following traumatic brain injury (TBI) among individuals with moderate-to-severe TBI requiring rehabilitation and surviving at least 5 years.

METHODS

Using the prospective TBI Model Systems National Database, we calculated PTS incidence during acute hospitalization, and at years 1, 2, and 5 postinjury in a continuously followed cohort enrolled from 1989 to 2000 (n = 795). Incidence rates were stratified by risk factors, and adjusted relative risk (RR) was calculated. Late PTS associations with immediate (<24 h), early (24 h-7 day), or late seizures (>7 day) versus no seizure prior to discharge from acute hospitalization was also examined.

RESULTS

PTS incidence during acute hospitalization was highest immediately (<24 h) post-TBI (8.9%). New onset PTS incidence was greatest between discharge from inpatient rehabilitation and year 1 (9.2%). Late PTS cumulative incidence from injury to year 1 was 11.9%, and reached 20.5% by year 5. Immediate/early PTS RR (2.04) was increased for those undergoing surgical evacuation procedures. Late PTS RR was significantly greater for individuals who self-identified as a race other than black/white (year 1 RR = 2.22), and for black individuals (year 5 RR = 3.02) versus white individuals. Late PTS was greater for individuals with subarachnoid hemorrhage (year 1 RR = 2.06) and individuals age 23-32 (year 5 RR = 2.43) and 33-44 (year 5 RR = 3.02). Late PTS RR years 1 and 5 was significantly higher for those undergoing surgical evacuation procedures (RR: 3.05 and 2.72, respectively).

SIGNIFICANCE

In this prospective, longitudinal, observational study, PTS incidence was similar to that in studies published previously. Individuals with immediate/late seizures during acute hospitalization have increased late PTS risk. Race, intracranial pathologies, and neurosurgical procedures also influenced PTS RR. Further studies are needed to examine the impact of seizure prophylaxis in high-risk subgroups and to delineate contributors to race/age associations on long-term seizure outcomes.

Repetitive Traumatic Brain Injury in Patients From Kashan, Iran

Background

Traumatic brain injury (TBI) is a worldwide problem, especially in countries with high incidence of road traffic accidents such as Iran. Patients with a single occurrence of TBI have been shown to be at increased risk to sustain future TBI.

Objectives

The aim of this study was to present the incidence and characteristics of repeated TBI (RTBI) in Iranian patients.

Patients and Methods

During one year, all admitted TBI patients with prior TBI history were enrolled into the study. In each patient, data such as age, gender, past medical history, injury cause, anatomic site of injury, TBI severity, clinical findings and CT scan findings were collected.

Results

RTBI comprised 2.5% of TBI cases (41 of 1629). The incidence of RTBI per 100,000 individuals per years was 9.7. The main cause of RTBI was road traffic accident (68.3%); 9.7 % of cases had preexisting seizure/epilepsy disorder; 36.6% of patients with RTBI had pervious ICU admission due to severe TBI. Ten patients had Glasgow coma scale (GCS) ≤ 13 (24.4%). Seizure was seen in seven patients (17.1%). Thirty-nine percent of patients with RTBI had associated injuries. Eleven patients had abnormal CT scan findings (26.9%).

Conclusions

Considering the high incidence of trauma in developing countries, RTBI may also be more common compared with that of developed countries. This mandates a newer approach to preventive strategies, particularly in those with a previous experience of head injury.

Cognitive changes and dementia risk after traumatic brain injury: implications for aging military personnel

Traumatic brain injury (TBI) is recognized as an important risk factor for the long-term cognitive health of military personnel, particularly in light of growing evidence that TBI increases risk for Alzheimer's disease and other dementias. In this article, we review the neurocognitive and neuropathologic changes after TBI with particular focus on the potential risk for cognitive decline across the life span in military service members. Implications for monitoring and surveillance of cognition in the aging military population are discussed. Additional studies are needed to clarify the factors that increase risk for later life cognitive decline, define the mechanistic link between these factors and dementia, and provide empirically supported interventions to mitigate the impact of TBI on cognition across the life span.

Frequency and impact of recurrent traumatic brain injury in a population-based sample

The aim of this study was to determine the frequency, mechanism(s), and impact of recurrent traumatic brain injury (TBI) over a 1-year period. Population-based TBI incidence and 1-year outcomes study with embedded case-control analysis. All participants (adults and children) who experienced a recurrent TBI (more than one) in the 12 months after an index injury and matched controls who sustained one TBI within the same period were enrolled in a population-based TBI incidence and outcomes study. Details of all recurrent TBIs sustained within 12 months of the initial index injury were recorded. Each recurrent TBI case was matched to a case sustaining one TBI based on age (±2 years), gender, and index TBI severity. Cognitive ability, disability, and postconcussion symptoms (PCS) were assessed 1 year after the index injury. Overall, 9.9% (n=72) of TBI cases experienced at least one recurrent TBI within the year after initial index injury. Males, people <35 years of age, and those who had experienced a TBI before their index injury were at highest risk of recurrent TBI. Recurrent TBI cases reported significantly increased PCS at 1 year, compared to the matched controls (n=72) sustaining one TBI. There was no difference in overall cognitive ability and disability between the two groups. People experiencing recurrent TBIs are more likely to experience increased frequency and severity of PCS. Greater public awareness of the potential effects of recurrent brain injury is needed.

The impact of previous traumatic brain injury on health and functioning: a TRACK-TBI study

The idea that multiple traumatic brain injury (TBI) can have a cumulative detrimental effect on functioning is widely accepted. Most research supporting this idea comes from athlete samples, and it is not known whether remote history of previous TBI affects functioning after subsequent TBI in community-based samples. This study investigates whether a previous history of TBI with loss of consciousness (LOC) is associated with worse health and functioning in a sample of individuals who require emergency department care for current TBI. Twenty-three percent of the 586 individuals with current TBI in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury study reported having sustained a previous TBI with LOC. Individuals with previous TBI were more likely to be unemployed (χ(2)=17.86; p=0.000), report a variety of chronic medical and psychiatric conditions (4.75≤χ(2)≥24.16; p<0.05), and report substance use (16.35≤χ(2)≥27.57; p<0.01) before the acute injury, compared to those with no previous TBI history. Those with a previous TBI had less-severe acute injuries, but experienced worse outcomes at 6-month follow-up. Results of a series of regression analyses controlling for demographics and acute injury severity indicated that individuals with previous TBI reported more mood symptoms, more postconcussive symptoms, lower life satisfaction, and had slower processing speed and poorer verbal learning, compared to those with no previous TBI history. These findings suggest that history of TBI with LOC may have important implications for health and psychological functioning after TBI in community-based samples.

Incidence of sport-related traumatic brain injury and risk factors of severity: a population-based epidemiologic study

PURPOSE

Few studies of sport-related traumatic brain injury (TBI) are population-based or rely on directly observed data on cause, demographic characteristics, and severity. This study addresses the epidemiology of sport-related TBI in a large population.

METHODS

Data on all South Carolina hospital and emergency department encounters for TBI, 1998-2011, were analyzed. Annual incidence rate of sport-related TBI was calculated, and rates were compared across demographic groups. Sport-related TBI severity was modeled as a function of demographic and TBI characteristics using logistic regression.

RESULTS

A total of 16,642 individuals with sport-related TBI yielded an average annual incidence rate of 31.5/100,000 population with a steady increase from 19.7 in 1998 to 45.6 in 2011. The most common mechanisms of sport-related TBI were kicked in football (38.1%), followed by fall injuries in sports (20.3%). Incidence rate was greatest in adolescents ages 12-18 (120.6/100,000/persons). Severe sport-related TBI was strongly associated with off-road vehicular sport (odds ratio [OR], 4.73; 95% confidence interval [95% CI], 2.92-7.67); repeated head trauma (OR, 4.36; 95% CI, 3.69-5.15); equestrian sport (OR, 2.73; 95% CI, 1.64-4.51); and falls during sport activities (OR, 2.72; 95% CI, 1.67-4.46).

CONCLUSIONS

The high incidence of sport-related TBI in youth, potential for repetitive mild TBI, and its long-term consequences on learning warrants coordinated surveillance activities and population-based outcome studies.

Prior history of traumatic brain injury among persons in the Traumatic Brain Injury Model Systems National Database

OBJECTIVE

To determine the association between demographic, psychosocial, and injury-related characteristics and traumatic brain injury (TBI) occurring prior to a moderate or severe TBI requiring rehabilitation.

DESIGN

Secondary data analysis.

SETTING

TBI Model System inpatient rehabilitation facilities.

PARTICIPANTS

Persons (N=4464) 1, 2, 5, 10, 15, or 20 years after TBI resulting in participation in the TBI Model System National Database.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

History of TBI prior to the TBI Model System Index injury, pre-Index injury demographic and behavioral characteristics, Index injury characteristics, post-Index injury behavioral health and global outcome.

RESULTS

Twenty percent of the cohort experienced TBIs preceding the TBI Model System Index injury-80% of these were mild and 40% occurred before age 16. Pre- and post-Index injury behavioral issues, especially substance abuse, were highly associated with having had a prior TBI. Greater severity of the pre-Index injury as well as occurrence before age 6 often showed stronger associations. Unexpectedly, pre-Index TBI was associated with less severe Index injuries and better functioning on admission and discharge from rehabilitation.

CONCLUSIONS

Findings suggest that earlier life TBI may have important implications for rehabilitation after subsequent TBI, especially for anticipating behavioral health issues in the chronic stage of recovery. Results provide additional evidence for the potential consequences of early life TBI, even if mild.

Tightly coupled repetitive blast-induced traumatic brain injury: development and characterization in mice

A mouse model of repeated blast exposure was developed using a compressed air-driven shock tube, to study the increase in severity of traumatic brain injury (bTBI) after multiple blast exposures. Isoflurane anesthetized C57BL/6J mice were exposed to 13.9, 20.6, and 25 psi single blast overpressure (BOP1) and allowed to recover for 5 days. BOP1 at 20.6 psi showed a mortality rate of 2% and this pressure was used for three repeated blast exposures (BOP3) with 1 and 30 min intervals. Overall mortality rate in BOP3 was increased to 20%. After blast exposure, righting reflex time and body-weight loss were significantly higher in BOP3 animals compared to BOP1 animals. At 4 h, brain edema was significantly increased in BOP3 animals compared to sham controls. Reactive oxygen species in the cortex were increased significantly in BOP1 and BOP3 animals. Neuropathological analysis of the cerebellum and cerebral cortex showed dense silver precipitates in BOP3 animals, indicating the presence of diffuse axonal injury. Fluoro-Jade B staining showed increased intensity in the cortex of BOP3 animals indicating neurodegeneration. Rota Rod behavioral test showed a significant decrease in performance at 10 rpm following BOP1 or BOP3 at 2 h post-blast, which gradually recovered during the 5 days. At 20 rpm, the latency to fall was significantly decreased in both BOP1 and BOP3 animals and it did not recover in the majority of the animals through 5 days of testing. These data suggest that repeated blast exposures lead to increased impairment severity in multiple neurological parameters of TBI in mice.