Number Of Traumatic Brain Injury Research Articles

The role and importance of helmet use in the prevention of traumatic brain injury – a literature review

Protective helmets are used in a wide range of professional, sport and recreational activities. They undoubtedly play a very important role in the prevention of head injuries, including traumatic brain injury. There is no doubt that they improve user safety. The main aim of the following paper is to analyse recent publications and studies describing to what extent a helmet can protect against traumatic brain injury and its consequences. Traumatic brain injury is the disruption of brain function or the presence of any other pathology in the brain caused by physical force. There are many head injuries worldwide that result in traumatic brain injury. The effects of these accidents can be reduced by using safety helmets. Statistics quite clearly show that helmets realistically reduce the number of traumatic brain injuries, as well as their consequences. Injuries sustained by people who wore a helmet on their head at the time of the accident were less severe, gave less serious complications and were also less likely to be fatal compared to injuries acquired when a helmet was not worn on the head. The wearing of helmets has been made compulsory in many places and this has had a significant impact on the decrease in the incidence of severe brain injuries. The use of protective helmets is correlated with milder and less frequent head injuries and fewer complications of these injuries. Public awareness of traumatic brain injury is still low. Although the benefits of wearing helmets are widely known, there are still many people who do not use this method of head injury prevention. Awareness campaigns, notification systems or other innovative methods are just a few of the many ways in which attempts are made to draw the public’s attention to the need to wear a helmet during activities with a higher risk of head injury.

Results of cranioplasty using individual titanium implants

Background. Despite its long history, cranioplasty remains a topical problem of neurosurgery, due to the increasing number of traumatic brain injury, the consequences of which are the main driver in preserving the population of patients with postcranioectomy skull defects. As a rule, these defects are extensive, and the use of individual implants in these cases is the method of choice. Over the past 5 years, the use of products created by medical additive manufacturing has increased, in this regard, the assessment of long-term results of surgical interventions with their use is an actual issue of modern medicine.Aim. To evaluate the results of surgical treatment of patients with skull defects of various etiologies using individual titanium implants made by three-dimensional printing.Materials and methods. The study analyzed 94 cases of cranioplasty using individual titanium implants made by three-dimensional printing using DMLS (Direct Metal Laser Sintering) technology. The minimum follow-up period was 12 months from the moment of the intervention. Traumatic brain injury and its consequences was the dominant cause of skull bone defects (n = 56, 59.6 %). The average area of defects in the study group was 99.2 ± 43.4 cm2. For men (n = 53), this parameter corresponded to 106.7 ± 44.7 cm2, for women (n = 41) – 89.5 ± 40.1 cm2.Results. The total number of complications in the study group was 12 (12.7 %) cases, of which 5 (5.3 %) cases were recorded during the in hospital stay of patients, 7 (7.4 %) – during outpatient follow-up. One complication was not related to the performed surgical intervention. Removal of the implant was required in 7 (7.4 %) cases. The terms of implant removal varied from 0 to 14 months from the moment of the performed intervention. The survival rate of individual titanium implants for more than 12 months was 92.6 %.Conclusion. The data on the presence of complications after cranioplasty vary from study to study, while the results of reconstructive interventions performed using individual titanium implants are of significant interest, the use of which has increased significantly over the past five years due to the introduction of additive medical production into clinical practice.

Current trends and outcomes of non-elective neurosurgical care in Central Europe during the second year of the COVID-19 pandemic

Reflecting the first wave COVID-19 pandemic in Central Europe (i.e. March 16th–April 15th, 2020) the neurosurgical community witnessed a general diminution in the incidence of emergency neurosurgical cases, which was impelled by a reduced number of traumatic brain injuries (TBI), spine conditions, and chronic subdural hematomas (CSDH). This appeared to be associated with restrictions imposed on mobility within countries but also to possible delayed patient introduction and interdisciplinary medical counseling. In response to one year of COVID-19 experience, also mapping the third wave of COVID-19 in 2021 (i.e. March 16 to April 15, 2021), we aimed to reevaluate the current prevalence and outcomes for emergency non-elective neurosurgical cases in COVID-19-negative patients across Austria and the Czech Republic. The primary analysis was focused on incidence and 30-day mortality in emergency neurosurgical cases compared to four preceding years (2017–2020). A total of 5077 neurosurgical emergency cases were reviewed. The year 2021 compared to the years 2017–2019 was not significantly related to any increased odds of 30 day mortality in Austria or in the Czech Republic. Recently, there was a significant propensity toward increased incidence rates of emergency non-elective neurosurgical cases during the third COVID-19 pandemic wave in Austria, driven by their lower incidence during the first COVID-19 wave in 2020. Selected neurosurgical conditions commonly associated with traumatic etiologies including TBI, and CSDH roughly reverted to similar incidence rates from the previous non-COVID-19 years. Further resisting the major deleterious effects of the continuing COVID-19 pandemic, it is edifying to notice that the neurosurgical community´s demeanor to the recent third pandemic culmination keeps the very high standards of non-elective neurosurgical care alongside with low periprocedural morbidity. This also reflects the current state of health care quality in the Czech Republic and Austria.

Tau as a fluid biomarker of concussion and neurodegeneration.

Concussion is predominant among the vast number of traumatic brain injuries that occur worldwide. Difficulties in timely identification, whether concussion led to neuronal injury or not, diagnosis and the lack of prognostic tools for adequate management could lead this type of brain injury to progressive neurodegenerative diseases. Tau has been extensively studied in recent years, particularly in repetitive mild traumatic brain injuries and sports-related concussions. Tauopathies, the group of neurodegenerative diseases, have also been studied with advanced functional imaging. Nevertheless, neurodegenerative diseases, such as chronic traumatic encephalopathy, are still conclusively diagnosed at autopsy. Here, we discuss the diagnostic dilemma and the relationship between concussion and neurodegenerative diseases and review the literature on tau as a promising biomarker for concussion.

P.0098 Number of traumatic brain injuries and temporal associations with depression: A Danish register-based cohort study

P.0098 Number of traumatic brain injuries and temporal associations with depression: A Danish register-based cohort study

Trajectories and Predictors of Anxiety Over a Ten-year Duration after Traumatic Brain Injury: A TBIMS Study

<h3>Research Objectives</h3> To determine anxiety trajectories across the first 10 years after traumatic brain injury (TBI), and to identify predictors of the longitudinal course of anxiety. <h3>Design</h3> Longitudinal cohort study. <h3>Setting</h3> Community. <h3>Participants</h3> 2836 participants with moderate to severe TBI enrolled in the Traumatic Brain Injury Model Systems (TBIMS) National Database who had anxiety outcomes for ≥2 data collection points over a 10-year follow-up period. <h3>Interventions</h3> N/A. <h3>Main Outcome Measures</h3> Generalized Anxiety Disorder-7 (GAD-7) at 1, 2, 5, and 10-year follow-ups. Relationships were examined with demographic variables, indicators of TBI severity, number of TBIs in addition to the index TBI, pre-morbid mental health, and substance abuse history. <h3>Results</h3> A latent class mixed model identified three anxiety trajectories: low-stable (n=2195), increasing (n=289), and decreasing (n=352). Higher GAD-7 scores were significantly associated with Black race, having public insurance, premorbid mental health problems, experiencing ≥2 additional TBIs with loss of consciousness (LOC), and increased years post-TBI. An interaction between follow-up year and age was also related to GAD-7 scores (p=.001). <h3>Conclusions</h3> Most individuals in the sample had low anxiety that was stable over time (77%). Smaller percentages of individuals had higher levels of anxiety, that either increased (10%) or decreased (13%) as time progressed. Multiple TBI's with LOC were related to greater anxiety up to 10 years after injury. Systemic economic and racial inequities likely contribute to long-term anxiety, as evidenced by greater anxiety in those who had public insurance and/or identified as Black. Younger individuals were more likely to experience an increase in their anxiety over time, suggesting a need for long-term anxiety surveillance, particularly for patients whose TBI occurred at an earlier stage in life. <h3>Author(s) Disclosures</h3> None.

Utilizing the BAT-LQ to assess TBI incidence in a college student population

ABSTRACT Objective: Although the annual number of traumatic brain injuries (TBIs) reported in the US exceeds two million, data suggests that this is an underestimate. The goal of this study was to understand lifetime TBI incidence among a sample of college students. Additionally, this study examined whether a single yes/no question regarding TBI history was sufficient to gather accurate information about TBI incidence in college students. Design: Participants were asked a single TBI question and administered the BAT-LQ. Main Measures: The BAT-LQ is a screening tool designed to assess for probable lifetime TBIs. Results: Data from 121 participants were analyzed for this study. On the single-question, 24.8% of participants reported experiencing a TBI. However, upon further prompting, 76.8% of all participants reported experiencing a blow to the head accompanied by at least one diagnostic symptom of a TBI, suggesting a probable TBI based on best-practice diagnosis guidelines. Conclusion: The results of this study suggest that increased education about TBI is warranted to ensure that individuals receive care for probable TBIs, as many individuals likely lack knowledge about what constitutes a TBI diagnosis. Additionally, the results suggest that a single question may not be sufficient to capture true lifetime TBI incidence.

Number of traumatic brain injuries and temporal associations with depression: A register-based cohort study.

To explore the association of the number of traumatic brain injuries (TBIs) and temporal associations with the subsequent risk of depression in the population. National register-based cohort study on all individuals registered with TBI (ICD-10: S06, ICD-8: 85.0-85.5) from 1977 to 2015 in Denmark (n=494,216) and a sex- and age-matched reference population (n=499,505). The associations with the number of TBIs and time to depression (0-6, 7-12 and more than 12months following TBI) were analyzed using Cox proportional hazard regression. During a follow-up of mean 14.5 (SD 11.3) years, a total of 27,873 (5.6%) individuals who had at least one TBI and 15,195 (3.0%) in the reference population were diagnosed with a depression. First-time TBI was associated with a higher risk of depression in both men (HR=1.73 [95% CI:1.67-1.79]) and women (HR=1.66 [95% CI:1.61-1.70]) after multiple adjustments for educational status and comorbidities including previous depression, and the association became stronger in a dose-response association with the number of TBIs (test for trend p<0.01). The HRs for depression were highest the first 6months after the TBI in both men (HR=5.69 [95% CI:4.66-6.94]) and women (HR=4.55 [95% CI:3.93-5.26]) and decreased gradually the following year but remained elevated from one year after TBI until end of follow-up independent of the number of TBIs (p<0.01). The associations did not vary with age or calendar time. Traumatic brain injury is associated with a higher risk of depression, especially in the first months after TBI and the risk increases with the number of TBIs.

Trends and outcomes for non-elective neurosurgical procedures in Central Europe during the COVID-19 pandemic

The world currently faces the novel severe acute respiratory syndrome coronavirus 2 pandemic. Little is known about the effects of a pandemic on non-elective neurosurgical practices, which have continued under modified conditions to reduce the spread of COVID-19. This knowledge might be critical for the ongoing second coronavirus wave and potential restrictions on health care. We aimed to determine the incidence and 30-day mortality rate of various non-elective neurosurgical procedures during the COVID-19 pandemic. A retrospective, multi-centre observational cohort study among neurosurgical centres within Austria, the Czech Republic, and Switzerland was performed. Incidence of neurosurgical emergencies and related 30-day mortality rates were determined for a period reflecting the peak pandemic of the first wave in all participating countries (i.e. March 16th–April 15th, 2020), and compared to the same period in prior years (2017, 2018, and 2019). A total of 4,752 emergency neurosurgical cases were reviewed over a 4-year period. In 2020, during the COVID-19 pandemic, there was a general decline in the incidence of non-elective neurosurgical cases, which was driven by a reduced number of traumatic brain injuries, spine conditions, and chronic subdural hematomas. Thirty-day mortality did not significantly increase overall or for any of the conditions examined during the peak of the pandemic. The neurosurgical community in these three European countries observed a decrease in the incidence of some neurosurgical emergencies with 30-day mortality rates comparable to previous years (2017–2019). Lower incidence of neurosurgical cases is likely related to restrictions placed on mobility within countries, but may also involve delayed patient presentation.

Incidence (2008-2015) of post-traumatic headaches in United States military personnel

ABSTRACT Objective: To conduct a descriptive transversal study to evaluate the incidence and demographic characteristics of post-traumatic headache using data from the Defense Medical Epidemiology Database. Methods: A retrospective cohort study was conducted of data from 2008 to 2015 based on the International Classification of Diseases codes for both acute and chronic post-traumatic headache. Results: A total of 17,010 new cases of post-traumatic headaches were diagnosed among active duty military personnel. Reported incidence rates of post-traumatic headaches in the military increased 29-fold over the timeframe analyzed. Males enlisted in the Army were more likely to be diagnosed with post-traumatic headaches than females (O/E = 0.76), other branches, and officers. Conclusion: Findings of this study indicate that there is a significant incidence of post-traumatic headaches in the U.S. military. However, the incidence rates of post-traumatic headaches in the military are much lower than what was expected considering the number of traumatic brain injuries in the United States military reported by the Department of Defense for the same period. Additional research is needed to further evaluate these differences and the impact of PTHs on military personnel.

A-124 Acute Predictors of Chronic PTSD Symptoms Following TBI in U.S. Military Service Members

Abstract Objective Post-Traumatic Stress Disorder (PTSD) has been shown to be a major contributor to poor outcome after Traumatic Brain Injury (TBI). Understanding the factors that contribute to PTSD symptoms may lead to improved clinical management of PTSD and TBI. This study examines acute predictors of self-reported PTSD symptoms after TBI in military service members. Method Participants included 210 U.S. military service members (Age: M = 33.9 years, SD = 10.2) without injury (n = 86), or with history of uncomplicated mild TBI (n = 56), complicated mild, moderate, or severe TBI (n = 43), or bodily injury (n = 25) assessed at 0–8 months and ≥ 2 years post-injury. At both assessments, participants completed the PTSD Checklist (PCL-C), Neurobehavioral Symptom Inventory, Alcohol Use Disorder Checklist, Combat Exposure Scale, and TBI Quality of Life and passed symptom validity tests. Stepwise linear regression included 26 potential predictors (demographics, injury characteristics, military characteristics, and self-report measures at baseline) of PCL-C Total at follow-up. Results In this model, (F(4,188) = 68.0; p &amp;lt; .001; R2 = .591), baseline PCL-C (R2Δ = .52) was the main predictor of follow-up PCL-C Total, followed by Cognitive Concerns (R2Δ = .04), number of deployments (R2Δ = .01), and injury severity (R2Δ = .02). When baseline PCL-C was excluded as a predictor, somatosensory symptoms (R2Δ = .361), Emotional/Behavioral Dyscontrol (R2Δ = .067), Sleep (R2Δ = .033), Combat Exposure (R2Δ = .024), and Cognitive Concerns (R2Δ = .017) predicted follow-up PCL-C (F(5,187) = 37.7; p &amp;lt; .001; R2 = .502). Semipartial correlations revealed that most of the explained variance was shared among self-report predictors. Conclusion Findings suggest acute psychological distress impacts future PTSD symptomatology, whereas TBI characteristics, such as TBI severity and number of TBIs, have minimal influence.

Standard motorcycle helmet usage and its effect on road traffic safety in the two major cities of Vietnam

The number and severity of road accidents in Vietnam is at alarming rate. From 2003, the Government has tried to improve traffic safety, therefore the number of accident and traumatic brain injury (TBI) and the rate of death reduced suddenly. However, from the end of 2008, even though accident number decreasing, a number of TBI and deaths due to road crash are jumping up. This paper aims to analyze the reason of heavy injuries, TBI and deaths happening increased. The specific surveys were taken to motorcyclists, helmet market, traffic safety agencies and hospital in Hanoi and Ho Chi Minh City. Statistic method, integrated comparison, observation, expert interview survey and brainstorming method have been used in this study to analyze the problem. Then road safety situation, helmet usage, regulation and enforcement were analyzed. Base on these, proposal to improve road safety in the two major cities in Vietnam is going to be discussed.

Using Gas-Driven Shock Tubes to Produce Blast Wave Signatures.

The increased incidence of improvised explosives in military conflicts has brought about an increase in the number of traumatic brain injuries (TBIs) observed. Although physical injuries are caused by shrapnel and the immediate blast, encountering the blast wave associated with improvised explosive devices (IEDs) may be the cause of traumatic brain injuries experienced by warfighters. Assessment of the effectiveness of personal protective equipment (PPE) to mitigate TBI requires understanding the interaction between blast waves and human bodies and the ability to replicate the pressure signatures caused by blast waves. Prior research has validated compression-driven shock tube designs as a laboratory method of generating representative pressure signatures, or Friedlander-shaped blast profiles; however, shock tubes can vary depending on their design parameters and not all shock tube designs generate acceptable pressure signatures. This paper presents a comprehensive numerical study of the effects of driver gas, driver (breech) length, and membrane burst pressure of a constant-area shock tube. Discrete locations in the shock tube were probed, and the blast wave evolution in time at these points was analyzed to determine the effect of location on the pressure signature. The results of these simulations are used as a basis for suggesting guidelines for obtaining desired blast profiles.

Associations of Lifetime Traumatic Brain Injury Characteristics With Prospective Suicide Attempt Among Deployed US Army Soldiers.

To estimate associations of lifetime traumatic brain injury (TBI) characteristics with prospective suicide attempt among US Army soldiers. The Army STARRS (Study to Assess Risk and Resilience in Servicemembers) Pre/Post Deployment Study surveyed 3 Brigade Combat Teams that were deployed to Afghanistan in 2012. Lifetime TBI and past-month postconcussive/post-TBI symptoms were evaluated at predeployment baseline. Recency and number of TBIs were quantified, and TBI severity was classified on the basis of reports of alteration/loss of consciousness and memory lapse. Suicide attempt data came from administrative records and surveys administered after return from deployment. Logistic regression models estimated associations of TBI characteristics with prospective suicide attempt among baseline respondents who were deployed (n = 7677), adjusting for other risk factors including lifetime mental disorder. One hundred three soldiers made a suicide attempt over a median follow-up period of 30 months (weighted prevalence = 1.31% [0.14%]). In the final model estimating joint associations of TBI severity/recency and past-month postconcussive/post-TBI symptoms, only postconcussive/post-TBI symptoms were associated with a higher risk of suicide attempt (per standard score increase: AOR [adjusted odds ratio] = 1.31; 95% CI, 1.05-1.63; P = .012). Among the lifetime TBI characteristics evaluated at predeployment baseline, only past-month postconcussive/post-TBI symptoms were prospectively associated with an increased risk of suicide attempt following deployment. Detection of postconcussive/post-TBI symptoms could facilitate targeting of Army suicide prevention programs.

Insomnia prevalence among U.S. Army soldiers with history of TBI.

To determine the rate of insomnia among active-duty soldiers with and without a history of traumatic brain injury (TBI). Research Method and Design: Data were extracted from the All Army Study (AAS), a cross-sectional, self-report survey completed by a representative sample of 21,499 U.S. Army soldiers from 2011 to 2013 as part of the Army Study to Assess Risk and Resilience in Servicemembers. History and severity of TBI were determined by participants' responses to questions regarding postinjury symptomology (i.e., loss of consciousness [LOC], amnesia, etc.). Insomnia symptoms were defined using DSM-5 criteria as measured by the Brief Insomnia Questionnaire. Approximately 63% of respondents reported lifetime history of mild TBI (mTBI), with ∼7% endorsing a history of moderate to severe TBI. Insomnia symptom prevalence rate increased with brain injury severity and number of TBIs with LOC, with ∼51% of those with mTBI and ∼55% of those with moderate to severe TBI demonstrating clinically elevated insomnia symptoms, compared to ∼37% insomnia prevalence rate among servicemembers without TBI. Results suggest high (> 50%) prevalence rates of insomnia symptoms among servicemembers with a lifetime history of brain injury, underscoring the need for behavioral sleep medicine interventions among active-duty personnel. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

B-75 A Preliminary Investigation of Predictors of Employment and Perception of Ability to Work in Combat-Exposed Veterans

Abstract Objective The purpose of this study was twofold: (1) to evaluate whether perception of one’s ability to work (a subjective rating) predicts employment status (an objective marker of functioning) in a sample of combat-exposed Veterans, and (2) to examine predictors of employment status and perception of work ability to determine whether the same sets of variables that predict employment status also predict perception of one’s ability to work. Method Combat-exposed Operation Enduring Freedom/Operation Iraqi Freedom Veterans (N = 83) completed self-report questionnaires assessing demographic characteristics, combat-related experiences, and psychiatric and neurobehavioral/health-related symptoms. Veterans also underwent a comprehensive neuropsychological assessment. Primary outcomes of interest were employment status (unemployed versus employed) and Veterans’ rating of a perceived decline in work ability (yes versus no). Results Logistic regression analyses showed that perception of work ability significantly predicted employment status (p = .046). Moreover, psychiatric and neurobehavioral/health-related symptoms significantly predicted employment status and perception of work ability (p = .001-.017), whereas demographic characteristics (i.e., service-connection disability rating) and combat-related experiences (i.e., number of traumatic brain injuries) only predicted perception of work ability (p = .010-.029). Cognition was not significantly associated with employment status or perception of work ability (p’s &gt; .05). Conclusions Altogether, these findings support the notion that perception of one’s ability to work plays an important role in employment-related outcomes in combat-exposed Veterans. Future studies using larger samples are needed to confirm these findings, but our preliminary results suggest that perception of work ability may be a particularly important treatment target in this population.

Plasma Tau and Amyloid Are Not Reliably Related to Injury Characteristics, Neuropsychological Performance, or White Matter Integrity in Service Members with a History of Traumatic Brain Injury.

The aim of this study was to examine the relationship between plasma tau and amyloid beta-42 (Aβ42), neuropsychological functioning, and white matter integrity in U.S. military service members with (n = 155) and without (n = 42) a history of uncomplicated mild (n = 83), complicated mild (n = 26), or moderate, severe, or penetrating (n = 46) traumatic brain injury (TBI). We hypothesized that higher levels of tau and Aβ42 would be related to reduced neurocognitive performance and white matter integrity. Participants were enrolled prospectively from Walter Reed National Military Medical Center. Participants completed a blood draw, neuropsychological assessment, and diffusion tensor imaging (General Electric 3T) of the whole brain. From 20 neuropsychological test scores, five cognitive domain scores were computed. Measures of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were generated for 18 regions of interest (ROIs). There was no relationship found between the plasma biomarkers and neurocognitive performance in any of the three TBI groups (all ps >0.05; all R2 changes <0.146). Although not reaching statistical significance after correction for multiple comparisons, higher tau and Aβ42 tended to be related to higher FA and lower MD, RD, and AD in patients with a history of moderate, severe, or penetrating TBI. There was no consistent relationship between either of the biomarkers and white matter integrity in the complicated and uncomplicated mild TBI groups. In addition, there was no significant relationship between the biomarkers and age, education, sex, race, bodily injury severity, time since injury, TBI severity, or number of TBIs (all ps >0.15). Future investigation in larger samples of moderate, severe, and penetrating TBI are needed. Other plasma biomarkers, including phosphorylated tau, exosomal tau, and interleukin-10, may be more promising measures to use in the diagnosis, management, and treatment of TBI.

Lifetime History of Traumatic Brain Injury and Current Disability Among Ohio Adults.

To examine the associations between lifetime history of traumatic brain injury (TBI) with loss of consciousness (LOC) and several types of current disability among adult, noninstitutionalized residents of Ohio. 2014 Ohio Behavioral Risk Factors Surveillance System participants (n = 6998). Statewide population-based survey. Lifetime history of TBI with LOC (number and severity of injury, age of first injury), and number and type of disability (vision, cognition, mobility, self-care, and/or independent living). Of the 6998 participants, 1325 reported lifetime history of TBI with LOC, and 1959 reported currently having one or more disabilities. When weighted, these represented 21.7% and 23.7% of Ohio's noninstitutionalized adult population, respectively. Adults with a history of TBI with LOC showed greater odds of any disability compared with adults with no history (odds ratio = 2.49; 95% confidence interval = 1.97-3.15). The likelihood of having any and each type of disability increased as the number of TBIs or the severity of worst TBI increased, regardless of sustaining first TBI before or after the age of 15 years. Lifetime history of TBI with LOC is significantly associated with disability among Ohio adults. Further research on the natural course of the relation and preventive strategies is warranted.

Long-term risk of dementia among people with traumatic brain injury in Denmark: a population-based observational cohort study.

Traumatic brain injury (TBI) has been associated with increased risk of dementia; however, large-scale studies with long follow-up have been scarce. We investigated the association between TBI, including severity and number of TBIs, and the subsequent long-term risk of dementia. We did a nationwide population-based observational cohort study in Denmark using information on citizens from national registries. We used the Danish Civil Registration System to establish a population-based cohort consisting of all people born in Denmark who were living in the country on Jan 1, 1995, and who were at least 50 years old at some point during follow-up (between 1999 and 2013). We obtained information on TBIs from the Danish National Patient Register (NPR), and obtained information on dementia by combining data recorded in the NPR, the Danish Psychiatric Central Register, and the Danish National Prescription Registry (DNPR). The long-term risk of dementia after TBI was established using survival analysis. We used three prespecified models for each of the three analyses: different time periods since the TBI, multiple TBIs, and sex. The first model adjusted for sociodemographic factors, the second model added medical and neurological comorbidities, and the third added psychiatric comorbidities. We used data from a cohort of 2 794 852 people for a total of 27 632 020 person-years (mean 9·89 years per patient) at risk of dementia. 132 093 individuals (4·7%) had at least one TBI during 1977-2013, and 126 734 (4·5%) had incident dementia during 1999-2013. The fully adjusted risk of all-cause dementia in people with a history of TBI was higher (hazard ratio [HR] 1·24, 95% CI 1·21-1·27) than in those without a history of TBI, as was the specific risk of Alzheimer's disease (1·16, 1·12-1·22). The risk of dementia was highest in the first 6 months after TBI (HR 4·06, 3·79-4·34) and also increased with increasing number of events (1·22, 1·19-1·25 with one TBI to 2·83, 2·14-3·75 with five or more TBIs). Furthermore, TBI was associated with a higher risk of dementia (1·29, 1·26-1·33) in people with TBI than in individuals with a non-TBI fracture not involving the skull or spine. The younger a person was when sustaining a TBI, the higher the HRs for dementia when stratified by time since TBI. TBI was associated with an increased risk of dementia both compared with people without a history of TBI and with people with non-TBI trauma. Greater efforts to prevent TBI and identify strategies to ameliorate the risk and impact of subsequent dementia are needed. Lundbeck Foundation.

The Effect of Traumatic Brain Injury History with Loss of Consciousness on Rate of Cognitive Decline Among Older Adults with Normal Cognition and Alzheimer’s Disease Dementia

Traumatic brain injury (TBI) is thought to be a risk factor for dementia, including dementia due to Alzheimer's disease (AD). However, the influence of TBI history on the neuropsychological course of AD is unknown and, more broadly, the effect of TBI history on age-related cognitive change is poorly understood. We examined the relationship between history of TBI with loss of consciousness (LOC) history and cognitive change in participants with normal cognition and probable AD, stratified by APOEɛ4 allele status. The sample included 706 participants (432 with normal cognition; 274 probable AD) from the National Alzheimer's Coordinating Center (NACC) dataset that completed the Uniform Data Set evaluation between 2005 and 2014. Normal and probable AD participants with a history of TBI were matched to an equal number of demographically and clinically similar participants without a TBI history. In this dataset, TBI with LOC was defined as brain trauma with brief or extended unconsciousness. For the normal and probable AD cohorts, there was an average of 3.2±1.9 and 1.8±1.1 years of follow-up, respectively. 30.8% of the normal cohort were APOEɛ4 carriers, whereas 70.8% of probable AD participants were carriers. Mixed effects regressions showed TBI with LOC history did not affect rates of cognitive change in APOEɛ4 carriers and non-carriers. Findings from this study suggest that TBI with LOC may not alter the course of cognitive function in older adults with and without probable AD. Future studies that better characterize TBI (e.g., severity, number of TBIs, history of subconconcussive exposure) are needed to clarify the association between TBI and long-term neurocognitive outcomes.