Neuropsychological performance following a history of multiple self-reported concussions: a meta-analysis

Adult cognitive ability and educational level in relation to concussions in childhood and adolescence: a population study of young men

OBJECTIVE

To investigate the relationship of concussion(s) suffered through childhood and adolescence with completed level of school education and cognitive ability in young adulthood.

METHODS

Educational level and scores on a test of cognitive ability were obtained for a cohort of 130,298 young men processed by the Danish draft board. Of these, 6146 had, at some age from birth onwards, been briefly admitted to hospital with a main discharge diagnosis of concussion. A further 402 had two such concussions and 48 had three or more.

RESULTS

Educational level and cognitive ability test scores were negatively associated with the number of concussions and the age at concussion(s). Most markedly, compared to the 123,684 non-concussed men, those with two or more concussions had lower educational levels (OR = 0.48; 95% CI = 0.26-0.89), as also did those sustaining one concussion between the age of 13 up to the time of testing (OR = 0.47: 0.42-0.52).

CONCLUSIONS

Since concussions do not generally have long-term effects, the results suggest that lower educational level is primarily a risk factor for sustaining a concussion at all ages, but in particular in adolescence more than in childhood and in the case of multiple concussions. It should, however, be recognized that, in some proportion of cases, the educational deficits have probably arisen as a consequence of the persistent symptoms of a lengthy post-concussional syndrome.

The impacts of injury at the individual, community and societal levels: a systematic meta-review

OBJECTIVES

Injury is a major public health problem. While the impacts of injury on the injured person are well documented, there is relatively little knowledge about the impacts of injury on those individuals and groups in the community connected to the injured person. This study seeks to describe this breadth of research using a meta-review methodology.

STUDY DESIGN

Systematic meta-review.

METHODS

To gain a better understanding of the known impacts of injury on family, community and society, a systematic meta-review of injury outcomes research literature was conducted. Seventy-eight peer-reviewed published literature reviews were included in the meta-review.

RESULTS

Of these, 70 reported outcomes at the level of the injured person including mortality, body functions, activity and participation limitations. Nine reviews reported impacts at the level of the community including impacts on family members, work colleagues and carers. Six studies reported impacts at the societal level including economic, health system and injury compensation system impacts.

CONCLUSIONS

In summary, the meta-review identified a substantial body of knowledge at the individual level outcomes of injury, and a relative lack of information regarding the community and societal impacts of injury. An injury outcome framework is proposed on the basis of the findings of the meta-review to guide future research activity, particularly with regard to injury outcome domains where there is currently limited evidence. A comprehensive framework that takes account of all levels of impact is necessary for effective policies, systems and strategies to support recovery following injury.

Chronic traumatic encephalopathy: where are we and where are we going?

Chronic traumatic encephalopathy (CTE, previously called punch drunk and dementia pugilistica) has a rich history in the medical literature in association with boxing, but has only recently been recognized with other contact sports, such as football and ice hockey, as well as with military blast injuries. CTE is thought to be a neurodegenerative disease associated with repeated concussive and subconcussive blows to the head. There is characteristic gross and microscopic pathology found in the brain, including frontal and temporal atrophy, axonal degeneration, and hyperphosphorylated tau and TAR DNA-binding protein 43 pathology. Clinically, there are characteristic progressive deficits in cognition (memory, executive dysfunction), behavior (explosivity, aggression), mood (depression, suicidality), and motor function (parkinsonism), which correlate with the anatomic distribution of brain pathology. While CTE shares clinical and neuropathological traits with other neurodegenerative diseases, the clinical syndrome and the neuropathology as a whole are distinct from other neurodegenerative diseases. Here we review the CTE literature to date. We also draw on the literature from mild traumatic brain injury and other neurodegenerative dementias, particularly when these studies provide guidance for future CTE research. We conclude by suggesting seven essential areas for future CTE research.

The effects of multiple mild traumatic brain injuries on acute injury presentation and neuropsychological recovery in children

BACKGROUND

Although research focused on mild traumatic brain injury (mTBI) has proliferated in recent years, few studies have examined the significance of a previous history of mTBI in children.

OBJECTIVE

To compare the acute injury presentation and neuropsychological recovery in a pediatric sample after mTBI.

METHODS

Participants 8 to 16 years of age were divided into 4 groups: no previous injury history, history of 1 mTBI, history of 2 mTBIs, and history of ≥ 3 mTBIs. Participants were evaluated within 3 months of the most recent injury by clinical interview and an abbreviated neuropsychological test battery.

RESULTS

After the index mTBI, the groups did not differ in their likelihood to display a loss of consciousness, nor did they differ on neuropsychological test performance.

CONCLUSION

Overall, contrary to our hypotheses, we found no demonstrable difference between those children with a self-reported mTBI history and those without after an index mTBI.

Computerized neurocognitive testing within 1 week of sport-related concussion: meta-analytic review and analysis of moderating factors

The purpose of this study is to perform a meta-analysis assessing the effects of sport-related concussion as measured by computerized neurocognitive tests (NCT) 1-week post injury. Thirty-seven studies involving 3960 participants between 2000 and 2011 were included. Hedge's g provides an adjusted effect size for smaller sample sizes and was calculated for overall and cognitive task effects, and subgroup analyses were conducted for age, type of NCT, and sport. Concussions had a low negative effect (g = -0.16; p < .001) across all groups, outcomes, and time points. Code substitution (g = -0.27; p < .05), visual memory (g = -0.25; p < .05), processing speed (g = -0.18; p < .05), and memory (g = -0.21; p < .05) tasks demonstrated negative effects for concussion. Younger adolescents had lower (g = -0.29; p < .05) NCT performance than older adolescents (g = -0.01) and college aged athletes (g = -0.11). ImPACT studies (g = -0.19; p < .05) demonstrated a negative effect for concussion as did those involving contact sports (g = -0.20; p < .05). A low to moderate overall effect size of concussion on neurocognitive performance was supported. Subgroup analyses revealed different effect sizes for specific cognitive tasks, types of NCTs, age, and type of sport.

Chronic traumatic encephalopathy and other neurodegenerative proteinopathies

"Chronic traumatic encephalopathy" (CTE) is described as a slowly progressive neurodegenerative disease believed to result from multiple concussions. Traditionally, concussions were considered benign events and although most people recover fully, about 10% develop a post-concussive syndrome with persisting neurological, cognitive and neuropsychiatric symptoms. CTE was once thought to be unique to boxers, but it has now been observed in many different athletes having suffered multiple concussions as well as in military personal after repeated blast injuries. Much remains unknown about the development of CTE but its pathological substrate is usually tau, similar to that seen in Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD). The aim of this "perspective" is to compare and contrast clinical and pathological CTE with the other neurodegenerative proteinopathies and highlight that there is an urgent need for understanding the relationship between concussion and the development of CTE as it may provide a window into the development of a proteinopathy and thus new avenues for treatment.

Cytoskeletal protein α-II spectrin degradation in the brain of repeated blast exposed mice

Repeated blast exposures commonly induce traumatic brain injury (TBI) characterized by diffuse axonal injury (DAI). We hypothesized that degradation of cytoskeletal proteins in the brain can lead to DAI, and evaluated α-II spectrin degradation in the pathophysiology of blast-induced TBI using the tightly-coupled three repetitive blast exposure mice model with a 1-30 min window in between exposures. Degradation of α-II spectrin and the expression profiles of caspase-3 and calpain-2, the major enzymes involved in the degradation were analyzed in the frontal cortex and cerebellum using Western blotting with specific antibodies. DAI at different brain regions was evaluated by neuropathology with silver staining. Repeated blast exposures resulted in significant increases in the α-II spectrin degradation products in the frontal cortex and cerebellum compared to sham controls. Expression of active caspase-3, which degrades α-II spectrin, showed significant increase in the frontal cortex after blast exposure at all the time points studied, while cerebellum showed an acute increase which was normalized over time. The expression of another α-II spectrin degrading enzyme, calpain-2, showed a rapid increase in the frontal cortex after blast exposure and it was significantly higher in the cerebellum at later time points. Neuropathological analysis showed significant levels of DAI at the frontal cortex and cerebellum at multiple time points after repeated blast injury. In summary, repeated blast exposure results in specific degradation of α-II spectrin in the brain along with differential expression of caspase-3/calpain-2 suggesting cytoskeletal breakdown as a possible contributor of DAI after repeated blast exposure.

Do injury characteristics predict the severity of acute neuropsychological deficits following sports-related concussion? A meta-analysis

The utility of injury characteristics for predicting the severity of post-concussion outcomes remains equivocal. The purpose of this meta-analysis was to quantify the predictive relationship between these variables to inform classification of acute injury severity. Thirty-one empirical samples of concussed athletes, for which rates of loss of consciousness and/or amnesia were reported, were included in a meta-analysis evaluating acute outcomes following sports-related concussion. Outcome measures of interest were neuropsychological tests first administered 1-10 days post-injury. Loss of consciousness and anterograde amnesia significantly predicted more severe neuropsychological deficits within 10 days of concussion in studies using pre-injury baseline, but not control group, comparisons. Retrograde amnesia significantly predicted acute neuropsychological dysfunction (d = -1.03) irrespective of comparison group. Although small sample sizes require conservative interpretation and future replication, the evidence suggests that retrograde amnesia, rather than loss of consciousness, may be used to classify the acute severity of concussion.

Executive functions and intraindividual variability following concussion

The long-term outcomes of executive functions and intraindividual variability (IIV; i.e., trial-to-trial or across-task variability in cognitive performance) following concussion are unclear due to inconsistent and limited research findings, respectively.

OBJECTIVE

Responding to these gaps in scientific understanding, the current study aimed to assess the utility of both executive functions and IIV at predicting concussion history.

METHOD

Altogether 138 self-identified athletes (Mage = 19.9 ± 1.91 years, 60.8% female, 19.6% with one concussion, 18.1% with two or more concussions) completed three executive-related cognitive tasks (i.e., n-back, go/no-go, global-local). Ordinal logistic regression analyses examined the joint effect of person-mean and IIV as predictors of concussion status.

RESULTS

Only mean response time for the global-local task predicted the number of past concussions, while no IIV variables reached unique significance.

CONCLUSIONS

IIV research on concussion remains limited; however, the preliminary results do not indicate any additional value of IIV indices above mean performances at predicting past concussion. For executive functions, shifting appears most sensitive at detecting concussion group differences, with past researchers identifying post concussion impairment in attentional processing.

A prospective study of gray matter abnormalities in mild traumatic brain injury

OBJECTIVE

To examine the underlying pathophysiology of mild traumatic brain injury through changes in gray matter diffusion and atrophy during the semiacute stage.

METHODS

Fifty patients and 50 sex-, age-, and education-matched controls were evaluated with a clinical and neuroimaging battery approximately 14 days postinjury, with 26 patients returning for follow-up 4 months postinjury. Clinical measures included tests of attention, processing speed, executive function, working memory, memory, and self-reported postconcussive symptoms. Measures of diffusion (fractional anisotropy [FA], mean diffusivity) and atrophy were obtained for cortical and subcortical structures to characterize effects of injury as a function of time.

RESULTS

Patients reported more cognitive, somatic, and emotional complaints during the semiacute injury phase, which were significantly reduced 4 months postinjury. Patients showed evidence of increased FA in the bilateral superior frontal cortex during the semiacute phase, with the left superior frontal cortex remaining elevated 4 months postinjury. There were no significant differences between patients and matched controls on neuropsychological testing or measures of gray matter atrophy/mean diffusivity at either time point.

CONCLUSIONS

Increased cortical FA is largely consistent with an emerging animal literature of gray matter abnormalities after neuronal injury. Potential mechanistic explanations for increased FA include cytotoxic edema or reactive gliosis. In contrast, there was no evidence of cortical or subcortical atrophy in the current study, suggesting that frank neuronal or neuropil loss does not occur early in the chronic disease course for patients with typical mild traumatic brain injury.

A comparison of insufficient effort rates, neuropsychological functioning, and neuropsychiatric symptom reporting in military veterans and civilians with chronic traumatic brain injury

Neuropsychological evaluation of persons with chronic traumatic brain injury (TBI) symptoms is complicated by multiple factors. The authors explored the impact of mechanism of injury, effort testing performance, and neuropsychiatric status in a sample of military veterans (V-TBI) and civilians (C-TBI) with chronic TBI. V-TBI (n = 74), C-TBI (n = 67), and healthy civilian control (C-HC) participants (n = 66), completed a battery of neuropsychological, effort, and self-report neuropsychiatric measures. Results indicated that C-HC and C-TBI participants exhibited comparably low failure rates on effort tests (6% and 3%, respectively). V-TBI participants exhibited significantly higher rates of failure (18%). Subgroups (n = 20) of effort-screened participants matched for demographics and disability level were compared regarding neuropsychological performance and neuropsychiatric self-report. Both TBI groups exhibited limited neuropsychological impairment, relative to the C-HC participants. The V-TBI group exhibited pronounced neuropsychiatric symptomology compared with the other participant groups. The implications of these findings are discussed for evaluation in the context of disability and litigation.

Neuropsychological differential diagnosis of mild traumatic brain injury

The diagnosis and evaluation of mild traumatic brain injury (mTBI) is reviewed from the perspective of meta-analyses of neuropsychological outcome, showing full recovery from a single, uncomplicated mTBI by 90 days post-trauma. Persons with history of complicated mTBI characterized by day-of-injury computed tomography or magnetic resonance imaging abnormalities, and those who have suffered prior mTBIs may or may not show evidence of complete recovery similar to that experienced by persons suffering a single, uncomplicated mTBI. Persistent post-concussion syndrome (PCS) is considered as a somatoform presentation, influenced by the non-specificity of PCS symptoms which commonly occur in non-TBI samples and co-vary as a function of general life stress, and psychological factors including symptom expectation, depression and anxiety. A model is presented for forensic evaluation of the individual mTBI case, which involves open-ended interview, followed by structured interview, record review, and detailed neuropsychological testing. Differential diagnosis includes consideration of other neurologic and psychiatric disorders, symptom expectation, diagnosis threat, developmental disorders, and malingering.

Traumatic brain injury and chronic traumatic encephalopathy: a forensic neuropsychiatric perspective

Recent scientific reports and popular press describing chronic traumatic encephalopathy (CTE) collectively link this condition to a broad array of neuropsychiatric symptoms, including extremely rare and multi-determined behaviors such as murder-suicide. These reports are difficult to reconcile with several decades of research on the science of traumatic brain injury (TBI) and its consequences, especially the natural history and prognosis of mild TBI. This article attempts to reconcile these sources by reviewing the state of the science on CTE, with particular attention to case definitions and neuropathological criteria for this diagnosis. The evidence for links between TBI, CTE, and catastrophic clinical events is explored, and the complexity of attributing rare frequency behavioral events to CTE is highlighted. The clinical and medicolegal implications of the best available evidence are discussed, concluding with a cautionary note against prematurely generalizing current findings on CTE to entire populations of persons with, or at risk for, concussion exposures.

Effects and outcomes in civilian and military traumatic brain injury: similarities, differences, and forensic implications

Traumatic brain injury (TBI) is a prominent public health problem in both civilian and military settings. This article discusses similarities and differences in the assessment and treatment of TBI and the attendant forensic implications. Acute care and management of moderate/severe TBI tend to be similar across environments, as is the recognition of disability status in affected individuals. By contrast, an increased focus on mild TBI in recent years has resulted in a reliance on self-report and screening measures to validate the occurrence of events leading to injury. This has complicated assessment, treatment and subsequent medicolegal proceedings. The neuropsychological literature has provided significant guidance on these difficult issues, although the complexity of disability adjudication for active duty members of the military and veterans continues to pose challenges for clinicians in evaluative and treatment contexts.

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.

Hypoconnectivity and hyperfrontality in retired American football players

Recent research has raised concerns about the long-term neurological consequences of repetitive concussive and sub-concussive injuries in professional players of American Football. Despite this interest, the neural and psychological status of retired players remains unknown. Here, we evaluated the performances and brain activation patterns of retired National Football League players (NFL alumni) relative to controls using an fMRI-optimised neuropsychological test of executive function. Behaviourally, the NFL alumni showed only modest performance deficits on the executive task. By contrast, they showed pronounced hyperactivation and hypoconnectivity of the dorsolateral frontal and frontopolar cortices. Critically, abnormal frontal-lobe function was correlated with the number of times that NFL alumni reported having been removed from play after head injury and was evident in individual players. These results support the hypothesis that NFL alumni have a heightened probability of developing executive dysfunction and suggest that fMRI provides the most sensitive biomarker of the underlying neural abnormality.

Subjective, but not objective, lingering effects of multiple past concussions in adolescents

The existing literature on lingering effects from concussions in children and adolescents is limited and mixed, and there are no clear answers for patients, clinicians, researchers, or policy makers. The purpose of this study was to examine whether there are lingering effects of past concussions in adolescent athletes. Participants in this study included 643 competitive Bantam and Midget hockey players (most elite 20% by division of play) between 13 and 17 years of age (mean age=15.5, SD=1.2). Concussion history at baseline assessment was retrospectively documented using a pre-season questionnaire (PSQ), which was completed at home by parents and players in advance of baseline testing. Players with English as a second language, self-reported attention or learning disorders, a concussion within 6 months of baseline, or suspected invalid test profiles were excluded from these analyses. Demographically adjusted standard scores for the five composites/domains and raw symptom ratings from the brief Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) computerized battery were analyzed. Adolescent athletes with one or two or more prior concussions did not have significantly worse neurocognitive functioning on ImPACT than did those with no previous concussions. There were significantly more symptoms reported in those with two or more prior concussions than in those with no or one prior concussion. Adolescents with multiple previous concussions had higher levels of baseline symptoms, but there were not group differences in neurocognitive functioning using this brief computerized battery.

Post-concussion symptom reporting after multiple mild traumatic brain injuries

The relationship between previous mild traumatic brain injury/injuries (MTBI) and recovery from a subsequent MTBI may be complex. The present study investigated three factors hypothesized to influence this relation: (1) the number of prior MTBIs, (2) the interval between MTBIs, and (3) the certainty level of previous MTBIs. The study design was retrospective cross-sectional. Participants (N=105) were evaluated at a concussion clinic on average 1 month after sustaining an MTBI, defined by World Health Organization diagnostic criteria. Approximately half the sample had at least one previous MTBI. Subgroups with 0, 1, or 2+ previous MTBIs did not differ in levels of current post-concussion symptom reporting on the British Columbia Post-Concussion Symptom Inventory. Time since the most recent previous MTBI was significantly associated with current post-concussion symptom reporting. This relation was best characterized as logarithmic; i.e., the impact of previous MTBI(s) lessens exponentially as time elapses to a subsequent MTBI. Defining previous MTBIs with a higher certainty level (i.e., probable versus possible) was not consistently associated with greater post-concussion symptom reporting. In conclusion, participants with multiple MTBIs did not report more post-concussion symptoms than those with no history of MTBI. Previous MTBI(s), however, were associated with increased symptom reporting from a subsequent MTBI to the extent they occurred closer in time. Having one or two previous remote MTBIs was not associated with worse outcome from subsequent MTBI in this sample.

Neuroimaging of cognitive dysfunction and depression in aging retired National Football League players: a cross-sectional study

OBJECTIVES To assess cognitive impairment and depression in aging former professional football (National Football League [NFL]) players and to identify neuroimaging correlates of these dysfunctions. DESIGN We compared former NFL players with cognitive impairment and depression, cognitively normal retired players who were not depressed, and matched healthy control subjects. SETTING Research center in the North Texas region of the United States. PATIENTS Cross-sectional sample of former NFL players with and without a history of concussion recruited from the North Texas region and age-, education-, and IQ-matched controls. Thirty-four retired NFL players (mean age, 61.8 years) underwent neurological and neuropsychological assessment. A subset of 26 players also underwent detailed neuroimaging; imaging data in this subset were compared with imaging data acquired in 26 healthy matched controls. MAIN OUTCOME MEASURES Neuropsychological measures, clinical diagnoses of depression, neuroimaging mea-sures of white matter pathology, and a measure of cerebral blood flow. RESULTS Of the 34 former NFL players, 20 were cognitively normal. Four were diagnosed as having a fixed cognitive deficit; 8, mild cognitive impairment; 2, dementia; and 8, depression. Of the subgroup in whom neuroimaging data were acquired, cognitively impaired participants showed the greatest deficits on tests of naming, word finding, and visual/verbal episodic memory. We found significant differences in white matter abnormalities in cognitively impaired and depressed retired players compared with their respective controls. Regional blood flow differences in the cognitively impaired group (left temporal pole, inferior parietal lobule, and superior temporal gyrus) corresponded to regions associated with impaired neurocognitive performance (problems with memory, naming, and word finding). CONCLUSIONS Cognitive deficits and depression appear to be more common in aging former NFL players compared with healthy controls. These deficits are correlated with white matter abnormalities and changes in regional cerebral blood flow.

Chronic postconcussion symptoms and functional outcomes in OEF/OIF veterans with self-report of blast exposure

Postconcussion symptoms (PCS) and functional outcomes were evaluated in 91 OEF/OIF outpatient veterans with reported histories of blast-exposure, with the goal of evaluating (1) the association between these outcomes and a clinical diagnosis of mild traumatic brain injury (mTBI) with or without loss of consciousness (LOC); and (2) the influence of post-traumatic stress disorder (PTSD) and depression on PCS reporting and perceived functional limitations. Individuals who reported mTBI with LOC had greater PCS complaints than individuals who reported mTBI without LOC or individuals without mTBI. However, after adjusting for severity of PTSD and depression symptoms, this group difference disappeared. Functional limitations were particularly prominent in the psychosocial domain. Again, PTSD was significantly associated with functional outcomes, but the mTBI with LOC group had greater psychosocial limitations than the other two groups, even when PTSD and depression symptoms were taken into account. These findings highlight the role of mental health in both outcomes, but additionally point to the impact of mTBI with LOC on long-term psychosocial adjustment.

Concussion in athletics: ongoing clinical and brain imaging research controversies

Concussion, the most common form of traumatic brain injury, proves to be increasingly complex and not mild in nature as its synonymous term mild traumatic brain injury (mTBI) would imply. Despite the increasing occurrence and prevalence of mTBI there is no universally accepted definition and conventional brain imaging techniques lack the sensitivity to detect subtle changes it causes. Moreover, clinical management of sports induced mild traumatic brain injury has not changed much over the past decade. Advances in neuroimaging that include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), resting-state functional connectivity, diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) offer promise in aiding research into understanding the complexities and nuances of mTBI which may ultimately influence clinical management of the condition. In this paper the authors review the major findings from these advanced neuroimaging methods along with current controversy within this field of research. As mTBI is frequently associated with youth and sports injury this review focuses on sports-related mTBI in the younger population.

Neuropsychological outcomes of U.S. Veterans with report of remote blast-related concussion and current psychopathology

This study explored whether remote blast-related MTBI and/or current Axis I psychopathology contribute to neuropsychological outcomes among OEF/OIF veterans with varied combat histories. OEF/OIF veterans underwent structured interviews to evaluate history of blast-related MTBI and psychopathology and were assigned to MTBI (n = 18), Axis I (n = 24), Co-morbid MTBI/Axis I (n = 34), or post-deployment control (n = 28) groups. A main effect for Axis I diagnosis on overall neuropsychological performance was identified (F(3,100) = 4.81; p = .004), with large effect sizes noted for the Axis I only (d = .98) and Co-morbid MTBI/Axis I (d = .95) groups relative to the control group. The latter groups demonstrated primary limitations on measures of learning/memory and processing speed. The MTBI only group demonstrated performances that were not significantly different from the remaining three groups. These findings suggest that a remote history of blast-related MTBI does not contribute to objective cognitive impairment in the late stage of injury. Impairments, when present, are subtle and most likely attributable to PTSD and other psychological conditions. Implications for clinical neuropsychologists and future research are discussed. (JINS, 2012, 18, 1-11).

Computational analysis reveals increased blood deposition following repeated mild traumatic brain injury

Mild traumatic brain injury (mTBI) has become an increasing public health concern as subsequent injuries can exacerbate existing neuropathology and result in neurological deficits. This study investigated the temporal development of cortical lesions using magnetic resonance imaging (MRI) to assess two mTBIs delivered to opposite cortical hemispheres. The controlled cortical impact model was used to produce an initial mTBI on the right cortex followed by a second injury induced on the left cortex at 3 (rmTBI 3d) or 7 (rmTBI 7d) days later. Histogram analysis was combined with a novel semi-automated computational approach to perform a voxel-wise examination of extravascular blood and edema volumes within the lesion. Examination of lesion volume 1d post last injury revealed increased tissue abnormalities within rmTBI 7d animals compared to other groups, particularly at the site of the second impact. Histogram analysis of lesion T2 values suggested increased edematous tissue within the rmTBI 3d group and elevated blood deposition in the rm TBI 7d animals. Further quantification of lesion composition for blood and edema containing voxels supported our histogram findings, with increased edema at the site of second impact in rmTBI 3d animals and elevated blood deposition in the rmTBI 7d group at the site of the first injury. Histological measurements revealed spatial overlap of regions containing blood deposition and microglial activation within the cortices of all animals. In conclusion, our findings suggest that there is a window of tissue vulnerability where a second distant mTBI, induced 7d after an initial injury, exacerbates tissue abnormalities consistent with hemorrhagic progression.

Cognitive sequelae of blast-induced traumatic brain injury: recovery and rehabilitation

Blast-related traumatic brain injury (bTBI) poses a significant concern for military personnel engaged in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF). Given the highly stressful context in which such injury occurs, psychiatric comorbidities are common. This paper provides an overview of mild bTBI and discusses the cognitive sequelae and course of recovery typical of mild TBI (mTBI). Complicating factors that arise in the context of co-morbid posttraumatic stress disorder (PTSD) are considered with regard to diagnosis and treatment. Relatively few studies have evaluated the efficacy of cognitive rehabilitation in civilian mTBI, but we discuss cognitive training approaches that hold promise for addressing mild impairments in executive function and memory, akin to those seen in OEF/OIF veterans with bTBI and PTSD. Further research is needed to address the patient and environmental characteristics associated with optimal treatment outcome.

Possible lingering effects of multiple past concussions

Background. The literature on lingering or “cumulative” effects of multiple concussions is mixed. The purpose of this study was to examine whether athletes with a history of three or more concussions perform more poorly on neuropsychological testing or report more subjective symptoms during a baseline, preseason evaluation. Hypothesis. Athletes reporting three or more past concussions would perform more poorly on preseason neurocognitive testing. Study Design. Case-control study. Methods. An archival database including 786 male athletes who underwent preseason testing with a computerized battery (ImPACT) was used to select the participants. Twenty-six athletes, between the ages of 17 and 22 with a history of three or more concussions, were identified. Athletes with no history of concussion were matched, in a case-control fashion, on age, education, self-reported ADHD, school, sport, and, when possible, playing position and self-reported academic problems. Results. The two groups were compared on the four neuropsychological composite scores from ImPACT using multivariate analysis of variance followed by univariate ANOVAs. MANOVA revealed no overall significant effect. Exploratory ANOVAs were conducted using Verbal Memory, Visual Memory, Reaction Time, Processing Speed, and Postconcussion Scale composite scores as dependent variables. There was a significant effect for only the Verbal Memory composite. Conclusions. Although inconclusive, the results suggest that some athletes with multiple concussions could have lingering memory deficits.

Neuropsychological and neuroimaging findings in traumatic brain injury and post-traumatic stress disorder

Advances in imaging technology, coupled with military personnel returning home from Iraq and Afghanistan with traumatic brain injury (TBI) and/or post-traumatic stress disorder (PTSD), have increased interest in the neuropsychology and neurobiology of these two conditions. There has been a particular focus on differential diagnosis. This paper provides an overview of findings regarding the neuropsychological and neurobiological underpinnings of TBI and for PTSD. A specific focus is on assessment using neuropsychological measures and imaging techniques. Challenges associated with the assessment of individuals with one or both conditions are also discussed. Although use of neuropsychological and neuroimaging test results may assist with diagnosis and treatment planning, further work is needed to identify objective biomarkers for each condition. Such advances would be expected to facilitate differential diagnosis and implementation of best treatment practices.

Trauma and impaired consciousness

This article discusses brain trauma and impaired consciousness. It reviews the various states of impaired consciousness related to trauma, with an historical and current literature viewpoint. The causes and pathophysiology of impaired consciousness in concussion, diffuse axonal injury, and focal brain lesions are discussed and management options evaluated.

Long-term consequences: effects on normal development profile after concussion

Each year in the United States, approximately 1.7 million people are diagnosed with a traumatic brain injury (TBI), about 75% of which are classified as mild TBIs or concussions. Although symptoms typically resolve in a matter of weeks, both children and adults may suffer from postconcussion syndrome for months or longer. A progressive tauopathy, chronic traumatic encephalopathy, is believed to stem from repeated brain trauma. Alzheimer-like dementia, Parkinsonism, and motor neuron disease are also associated with repetitive brain trauma. Effective diagnoses, treatments, and education plans are required to reduce the future burden and incidence of long-term effects of head injuries.

Repetitive closed-skull traumatic brain injury in mice causes persistent multifocal axonal injury and microglial reactivity

Repetitive mild or "concussive" traumatic brain injury (TBI) can cause substantial neurologic impairment, but the pathological features of this type of injury are not fully understood. We report an experimental model of TBI in which the closed skulls of anesthetized male C57BL/6J mice are struck with an electromagnetically controlled rubber impactor twice with an interval of 24 hours between impacts. The mice had deficits in Morris water maze performance in the first week after injury that only partially resolved 7 weeks later. By routine histology, there was no apparent bleeding, neuronal cell loss, or tissue disruption, and amyloid precursor protein immunohistochemistry demonstrated very few immunoreactive axonal varicosities. In contrast, silver staining revealed extensive abnormalities in the corpus callosum and bilateral external capsule, the ipsilateral cortex and thalamus, and the contralateral hippocampal CA1 stratum radiatum and stratum oriens. Electron microscopy of white matter regions demonstrated axonal cytoskeletal disruption, intra-axonal organelle compaction, and irregularities in axon caliber. Reactive microglia were observed in the same areas as the injured axons by both electron microscopy and Iba1 immunohistochemistry. Quantitative analyses of silver staining and Iba1 immunohistochemistry at multiple time points demonstrated transient cortical and thalamic abnormalities but persistent white matter pathology as late as 7 weeks after injury.Thus, prominent and long-lasting abnormalities in this TBI model were underestimated using conventional approaches. The model may be useful for mechanistic investigations and preclinical assessment of candidate therapeutics.

Neuropsychological evaluation of blast-related concussion: illustrating the challenges and complexities through OEF/OIF case studies

BACKGROUND/OBJECTIVE

Soldiers of Operations Enduring Freedom (OEF) and Iraqi Freedom (OIF) sustain blast-related mild traumatic brain injury (concussion) with alarming regularity. This study discusses factors in addition to concussion, such as co-morbid psychological difficulty (e.g. post-traumatic stress) and symptom validity concerns that may complicate neuropsychological evaluation in the late stage of concussive injury.

CASE REPORT

The study presents the complexities that accompany neuropsychological evaluation of blast concussion through discussion of three case reports of OEF/OIF personnel.

DISCUSSION

The authors emphasize uniform assessment of blast concussion, the importance of determining concussion severity according to acute-injury characteristics and elaborate upon non-concussion-related factors that may impact course of cognitive limitation. The authors conclude with a discussion of the need for future research examining the impact of blast concussion (particularly recurrent concussion) and neuropsychological performance.

Incremental contribution of reported previous head injury to the prediction of diagnosis and cognitive functioning in older adults

BACKGROUND

Severe brain injuries may be a risk factor for the development of dementia in later life. Less severe incidents with relatively short or even no loss of consciousness may not carry the same prognosis.

OBJECTIVES

This study used data from the first two waves of the Canadian Study of Health and Ageing (CSHA-1 and CSHA-2) to investigate two questions. (1) Does a history of head injury improve the prediction of the diagnosis of dementia? This analysis was based on the 921 elderly individuals who underwent a clinical assessment in CSHA-2 and, 5 years earlier, had reported whether or not they had had a head injury. (2) Does adding information about a history of head injury improve the prediction of neuropsychological test scores? This second analysis included 585 elderly people who underwent neuropsychological assessment in both waves and who also reported whether or not they had had a history of mild or moderate-to-severe head injury.

RESULTS

RESULTS showed that the inclusion of head injury information did not improve the prediction of diagnostic outcome of dementia. Age and overall cognitive status were associated with most neuropsychological test scores, more so than the more limited influence of chronic health problems, which was associated with about half of the neuropsychological measures.

Effects of traumatic brain injury on cognitive functioning and cerebral metabolites in HIV-infected individuals

We explored the possible augmenting effect of traumatic brain injury (TBI) history on HIV (human immunodeficiency virus) associated neurocognitive complications. HIV-infected participants with self-reported history of definite TBI were compared to HIV patients without TBI history. Groups were equated for relevant demographic and HIV-associated characteristics. The TBI group evidenced significantly greater deficits in executive functioning and working memory. N-acetylaspartate, a putative marker of neuronal integrity, was significantly lower in the frontal gray matter and basal ganglia brain regions of the TBI group. Together, these results suggest an additional brain impact of TBI over that from HIV alone. One clinical implication is that HIV patients with TBI history may need to be monitored more closely for increased risk of HIV-associated neurocognitive disorder signs or symptoms.

Rehabilitation in the patient with mild traumatic brain injury

Traumatic brain injury (TBI) has garnered increased public attention in the past several years because of high-profile athletes with possible long-term effects of their injuries as well as large numbers of returning combat veterans injured by blast explosions. Most of these injuries are mild in nature and require no specific surgical treatment but may benefit from brief rehabilitation interventions. To appropriately rehabilitate patients with mild traumatic brain injury (mTBI), one must fully understand its clinical course and the factors that accelerate or delay recovery. Education is the centerpiece of mTBI treatment and should be included in the rehabilitation plan. When devising the rehabilitation plan, the neurologist should take into account the goals of the patient and establish a reasonable time frame for treatment paralleling the expected recovery course. Cognitive and vestibular functions are commonly affected after mTBI and are particularly responsive to rehabilitation interventions. Vocational rehabilitation and community reentry planning are aspects of the global rehabilitation plan that should not be neglected. Combat-injured veterans with mTBI present unique challenges to the rehabilitation team, and assessment of these patients often needs to include assessment of psychological function.

Postconcussive symptoms after blast and nonblast-related mild traumatic brain injuries in Afghanistan and Iraq war veterans

Blast injury is common in current warfare, but little is known about the effects of blast-related mild traumatic brain injury (mTBI). Profile analyses were conducted investigating differences in self-reported postconcussive (PC) symptoms in 339 veteran outpatients with mTBI histories reporting current symptoms based on mechanism of injury (blast only, nonblast only, or both blast and nonblast), number of blast injuries, and distance from the blast. Veterans with any blast-related mTBI history were younger and reported higher posttraumatic stress symptoms than veterans with nonblast-related mTBI histories, with a marginally significant difference in posttraumatic stress symptom report between veterans reporting blast-related mTBI only and those reporting nonblast-related mTBI. The groups did not differ in terms of PC symptom severity or PC symptom cluster profiles. Among veterans with blast-related mTBI histories, PC symptom report did not vary by number of blast-related mTBIs or proximity to blast. Overall, posttraumatic stress symptoms accounted for a substantial portion of variance in PC symptom report. In veteran outpatients with remote mTBI histories who have enduring symptom complaints related to the mTBI, mechanism of injury did not clearly contribute to differential PC symptom severity or PC symptom cluster profile. Proximal rather than distal factors may be important intervention targets in returning symptomatic veterans with mTBI histories.