Neuropsychological studies of mild traumatic brain injury: a meta-analytic review of research since 1995

Do self-reported concussions have cumulative or enduring effects on drivers' anticipation of traffic hazards?

AIM

To investigate the cumulative effect of multiple self-reported concussions and the enduring effect of concussion on drivers' hazard perception ability. It was hypothesized: (1) that individuals reporting multiple previous concussions would be slower to anticipate traffic hazards than individuals reporting either one previous concussion or none; and (2) that individuals reporting a concussion within the past 3 months would be slower to anticipate traffic hazards than individuals reporting either an earlier concussion or no prior concussion.

METHOD

Two hundred and eighty-two predominantly young drivers (nconcussed = 68, Mage = 21.57 years, SDage = 6.99 years, 66% female) completed a validated hazard perception test (HPT) and measures of emotional, cognitive, health and driving status.

RESULTS

A one-way analysis of variance showed that there was no significant effect of concussion number on HPT response times. Similarly, pairwise comparisons showed no significant differences between the HPT response times of individuals reporting a concussion within the previous 3 months, individuals reporting an earlier concussion and the never concussed group.

CONCLUSION

The findings suggest that previous concussions do not adversely affect young drivers' ability to anticipate traffic hazards; however, due to reliance on self-reports of concussion history, further prospective longitudinal research is needed.

The neurological, neuroimaging and neuropsychological effects of playing professional football: Results of the UK five-year follow-up study

BACKGROUND

Whilst the scientific understanding of mild traumatic brain injury sequelae has advanced, the consequences of neurological insults sustained during football play in the form of multiple concussions and heading remains unclear.

METHOD

To the authors' knowledge, this is the first longitudinal prospective study to follow-up a group of footballers and controls over time. Thirty-two elite young professional footballers were recruited and 24 were identified at follow-up. Thirty-three controls were recruited and 17 identified at follow-up. Medical examination, MRI (brain) imaging and detailed neuropsychological data were collected on the footballers at baseline and 5-year follow-up. Medical examination and detailed neuropsychological data were collected on the controls at baseline and 5-year follow-up.

RESULTS

All participants had normal neurological examination at both time points. At baseline, 37% of the footballers had sustained minor neurological insults. Between baseline and 5 years, 66% of the footballers had sustained minor neurological insults. No MRI (brain) abnormalities were identified among the footballers at either time point. Regarding the neuropsychology, there was a 6-point IQ difference between footballers and controls, with the footballers being low. Test-re-test analysis on a range of carefully selected neurocognitive tests revealed a picture of good stability in cognitive functioning over this 5-year period.

CONCLUSIONS

These longitudinal prospective data indicate no significant neurological, structural brain imaging or neuropsychological change among a sample of young elite professional footballers over the first 5 years of their professional career.

Impact of Mild Head Injury on Neuropsychological Performance in Healthy Older Adults: Longitudinal Assessment in the AIBL Cohort

Traumatic brain injury (TBI) is suggested to be a significant risk factor for dementia. However, little research has been conducted into long-term neuropsychological outcomes after head trauma. Participants from the Australian Imaging, Biomarkers and Lifestyle Study of Ageing (AIBL) who had recovered after sustaining a mild TBI involving loss of consciousness more than 5 years previously were compared with matched controls across a 3-year period. Bayesian nested-domain modeling was used to estimate the effect of TBI on neuropsychological performance. There was no evidence for a chronic effect of mild TBI on any neuropsychological domain compared to controls. Within the TBI group, there was some evidence suggesting that the age that the head trauma occurred and the duration of unconsciousness were modulators of episodic memory. However, these findings were not robust. Taken together, these findings indicate that adults who have sustained a TBI resulting in loss of consciousness, but who recover to a healthy level of cognitive functioning, do not experience frank deficits in cognitive ability.

Pediatric validity assessment

BACKGROUND

Youth have been assumed historically to be less capable of deception than adults, even though acts of deception in childhood are not uncommon. Relatively little attention has focused on how frequently they feign or exaggerate during healthcare evaluations.

PURPOSE

The current article reviews the literature relevant to using validity tests in children and adolescents, as well as provides a case example of a young adolescent providing noncredible effort and exaggerated symptomatology during neuropsychological evaluation after a mild traumatic brain injury.

CONCLUSION

Numerous case reports and case series have documented clearly that medical and neuropsychological noncredible presentations occur in children, likely more often than many practitioners believe. Thus far, research has found that the base rates of pediatric noncredible presentations are highest in children seen frequently by rehabilitation providers (i.e., children with persistent problems after mild traumatic brain injury and children from families seeking disability benefits on their behalf). Subjective clinical judgment is apt to be ineffective in consistently detecting noncredible presentations. Fortunately, recent research supports the use of several stand-alone validity tests in identifying noncredible pediatric data including the Test of Memory Malingering, Word Memory Test, and Medical Symptom Validity Test. If feigning and exaggeration are not considered in work-ups by rehabilitation practitioners, mismanagement and iatrogenic harm to the child can result.

Virtual reality measures in neuropsychological assessment: a meta-analytic review

OBJECTIVE

Virtual reality-based assessment is a new paradigm for neuropsychological evaluation, that might provide an ecological assessment, compared to paper-and-pencil or computerized neuropsychological assessment. Previous research has focused on the use of virtual reality in neuropsychological assessment, but no meta-analysis focused on the sensitivity of virtual reality-based measures of cognitive processes in measuring cognitive processes in various populations.

METHOD

We found eighteen studies that compared the cognitive performance between clinical and healthy controls on virtual reality measures.

RESULTS

Based on a random effects model, the results indicated a large effect size in favor of healthy controls (g = .95). For executive functions, memory and visuospatial analysis, subgroup analysis revealed moderate to large effect sizes, with superior performance in the case of healthy controls. Participants' mean age, type of clinical condition, type of exploration within virtual reality environments, and the presence of distractors were significant moderators.

CONCLUSIONS

Our findings support the sensitivity of virtual reality-based measures in detecting cognitive impairment. They highlight the possibility of using virtual reality measures for neuropsychological assessment in research applications, as well as in clinical practice.

The effect of premorbid attention-deficit/hyperactivity disorder on neuropsychological functioning in individuals with acute mild traumatic brain injuries

INTRODUCTION

Mild traumatic brain injury (mTBI) is a frequent, yet undertreated condition that typically manifests with transient neurological and cognitive symptoms that resolve over the course of several weeks. In contrast, attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that presents initially in childhood but often persists into adulthood. mTBI and ADHD include overlapping symptomatology, making it difficult for clinicians to disentangle the sequelae of each condition when they co-occur in the same individual. We hypothesized that neuropsychological tests would be sensitive to preexisting ADHD in inpatients with acute mTBIs.

METHOD

We retrospectively examined the medical charts of 100 inpatients, aged 18-40 years (96% Caucasian; 77% male) with mTBIs in an acute care setting, half of whom had self-reported the presence of premorbid ADHD, and half of whom were matched controls. We analyzed group differences across neuropsychological tests of attention, processing speed, and executive functions, examined the profile ratings of independent, blinded, board-certified neuropsychologists, and correlated cognitive performance with time from traumatic injury to testing.

RESULTS

Individuals with premorbid ADHD (a) performed significantly worse than their matched counterparts on several tests of attention, processing speed, and working memory, and (b) were significantly more likely to produce profiles later rated as impaired by independent, board-certified clinical neuropsychologists. In addition, time from traumatic injury to testing was found to be negatively correlated with neurocognitive performance.

CONCLUSIONS

These findings (a) argue for the utility of a brief assessment of premorbid ADHD in the acute care of individuals with mTBIs and (b) provide clinicians with a barometer for gauging the relative contributions of premorbid ADHD to neuropsychological impairments in the neurocognitive profiles of individuals with mTBIs. Reported effect sizes will assist clinicians in accurately weighing the impact of premorbid ADHD when interpreting such profiles.

Executive Functioning of Combat Mild Traumatic Brain Injury

This study investigates neuropsychological deficits in recently deployed veterans with mild traumatic brain injury (mTBI). Veterans discharged from 2007 to 2012 were recruited from Veterans Affairs clinics. Independent groups of participants with mTBI (n = 57) and those without TBI (n = 57) were administered the Beck Depression Inventory-II, Combat Exposure Scale, Word Memory Test, and the Self-Awareness of Deficits Interview. Neuropsychological instruments included the Rey-Osterrieth Complex Figure Test, Letter and Category Fluency, Trail-Making Test-Parts A and B, Christiansen H-abbreviated, Soper Neuropsychology Screen, Wechsler Memory Scale subtests Logical Memory I and II, and the Street Completion Test. The mTBI group performed significantly worse on all of the executive and nonexecutive measurements with the exception of Category Fluency, after controlling for age, depression effort, and combat exposure. Depression and combat exposure were greater for the mTBI group. The mTBI group scored poorer on effort, but only the Multiple Choice subtest was significant. The mTBI group had good awareness of their deficits.

Determining client cognitive status following mild traumatic brain injury

BACKGROUND

People with mild traumatic brain injury (mTBI) commonly experience cognitive impairments. Occupational therapists working in acute general hospitals in Australia routinely access client Glasgow Coma Scale (GCS) scores, and assess cognitive status using standardized tools and by observing basic activity of daily living (ADL) performance. However, limited evidence exists to identify the best assessment(s) to determine client cognitive status.

AIM/OBJECTIVES

To determine whether cognitive status assessed by GCS score and the Cognistat are predictive of basic ADL performance among clients with mTBI in an acute general hospital and make inferences concerning the clinical utility of these assessment tools.

MATERIAL AND METHODS

Retrospective analysis of medical record data on demographics, Cognistat, GCS, and modified Barthel Index (MBI) using descriptive statistics, chi-square tests and linear regression.

RESULTS

Data analysis of 166 participants demonstrated that no associations exist between GCS and Cognistat scores, or Cognistat scores and MBI dependency level. The presence of co-morbid multi-trauma injuries and length of stay were the only variables that significantly predicted MBI dependency level.

CONCLUSION AND SIGNIFICANCE

While the MBI scores are of value in identifying clients with difficulty in basic ADLs, Cognistat and GCS scores are of limited use in differentiating client levels of cognitive impairment and the authors caution against the routine administration of the Cognistat following mTBI. Further research is required to identify more suitable assessments for use with a mTBI population.

Magnetoencephalography Slow-Wave Detection in Patients with Mild Traumatic Brain Injury and Ongoing Symptoms Correlated with Long-Term Neuropsychological Outcome

Mild traumatic brain injury (mTBI) is common in the United States, accounting for as many as 75-80% of all TBIs. It is recognized as a significant public health concern, but there are ongoing controversies regarding the etiology of persistent symptoms post-mTBI. This constellation of nonspecific symptoms is referred to as postconcussive syndrome (PCS). The present study combined results from magnetoencephalography (MEG) and cognitive assessment to examine group differences and relationships between brain activity and cognitive performance in 31 military and civilian individuals with a history of mTBI+PCS and 33 matched healthy control subjects. An operator-free analysis was used for MEG data to increase reliability of the technique. Subjects completed a comprehensive neuropsychological assessment, and measures of abnormal slow-wave activity from MEG were collected. Results demonstrated significant group differences on measures of executive functioning and processing speed. In addition, significant correlations between slow-wave activity on MEG and patterns of cognitive functioning were found in cortical areas, consistent with cognitive impairments on exams. Results provide more objective evidence that there may be subtle changes to the neurobiological integrity of the brain that can be detected by MEG. Further, these findings suggest that these abnormalities are associated with cognitive outcomes and may account, at least in part, for long-term PCS in those who have sustained an mTBI.

Sleep disturbances, TBI and PTSD: Implications for treatment and recovery

Post-Traumatic Stress Disorder (PTSD), traumatic brain injury (TBI), and sleep problems significantly affect recovery and functional status in military personnel and Veterans returning from combat. Despite recent attention, sleep is understudied in the Veteran population. Few treatments and rehabilitation protocols target sleep, although poor sleep remains at clinical levels and continues to adversely impact functioning even after the resolution of PTSD or mild TBI symptoms. Recent developments in non-pharmacologic sleep treatments have proven efficacious as stand-alone interventions and have potential to improve treatment outcomes by augmenting traditional behavioral and cognitive therapies. This review discusses the extensive scope of work in the area of sleep as it relates to TBI and PTSD, including pathophysiology and neurobiology of sleep; existing and emerging treatment options; as well as methodological issues in sleep measurements for TBI and PTSD. Understanding sleep problems and their role in the development and maintenance of PTSD and TBI symptoms may lead to improvement in overall treatment outcomes while offering a non-stigmatizing entry in mental health services and make current treatments more comprehensive by helping to address a broader spectrum of difficulties.

Concussions are associated with decreased batting performance among Major League Baseball players

BACKGROUND

Concussions impair balance, visual acuity, and reaction time--all of which are required for high-level batting performance--but the effects of concussion on batting performance have not been reported. The authors examined this relationship between concussion and batting performance among Major League Baseball (MLB) players.

HYPOTHESIS

Batting performance among concussed MLB players will be worse upon return to play than batting performance among players missing time for noninjury reasons.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors identified MLB players who sustained a concussion between 2007 and 2013 through league disabled-list records and a Baseball Prospectus database. For a comparison group, they identified players who went on paternity or bereavement leave during the same period. Using repeated-measures generalized linear models, the authors compared 7 batting metrics between the 2 groups for the 2 weeks upon return, as well as 4 to 6 weeks after return, controlling for pre-leave batting metrics, number of days missed, and position.

RESULTS

The authors identified 66 concussions and 68 episodes of bereavement/paternity leave to include in the analysis. In the 2 weeks after return, batting average (.235 vs .266), on-base percentage (.294 vs .326), slugging percentage (.361 vs .423), and on-base plus slugging (.650 vs .749) were significantly lower among concussed players relative to the bereavement/paternity leave players (time×group interaction, P<.05). In weeks 4 to 6 after leave, these metrics were slightly lower in concussed players but not statistically significantly so.

CONCLUSION

Although concussed players may be asymptomatic upon return to play, the residual effects of concussion on the skills required for batting may still be present. Further work is needed to clarify the mechanism through which batting performance after concussion is adversely affected and to identify better measures to use for return-to-play decisions.

FMRI hypoactivation during verbal learning and memory in former high school football players with multiple concussions

Multiple concussions before the age of 18 may be associated with late-life memory deficits. This study examined neural activation associated with verbal encoding and memory retrieval in former athletes ages 40-65 who received at least two concussions (median = 3; range = 2-15) playing high school football and a group of former high school football players with no reported history of concussions matched on age, education, and pre-morbid IQ. Functional magnetic resonance imaging data collected during a modified verbal paired associates paradigm indicated that those with concussive histories had hypoactivation in left hemispheric language regions, including the inferior/middle frontal gyri and angular gyrus compared with controls. However, concussive history was not associated with worse memory functioning on neuropsychological tests or worse behavioral performance during the paradigm, suggesting that multiple early-life concussions may be associated with subtle changes in the verbal encoding system that limits one from accessing higher-order semantic networks, but this difference does not translate into measurable cognitive performance deficits.

Diffusion tensor imaging findings in semi-acute mild traumatic brain injury

The past 10 years have seen a rapid increase in the use of diffusion tensor imaging to identify biomarkers of traumatic brain injury (TBI). Although the literature generally indicates decreased anisotropic diffusion at more chronic injury periods and in more severe injuries, considerable debate remains regarding the direction (i.e., increased or decreased) of anisotropic diffusion in the acute to semi-acute phase (here defined as less than 3 months post-injury) of mild TBI (mTBI). A systematic review of the literature was therefore performed to (1) determine the prevalence of different anisotropic diffusion findings (increased, decreased, bidirectional, or null) during the semi-acute injury phase of mTBI and to (2) identify clinical (e.g., age of injury, post-injury scan time, etc.) and experimental factors (e.g., number of unique directions, field strength) that may influence these findings. Results from the literature review indicated 31 articles with independent samples of semi-acute mTBI patients, with 13 studies reporting decreased anisotropic diffusion, 11 reporting increased diffusion, 2 reporting bidirectional findings, and 5 reporting null findings. Chi-squared analyses indicated that the total number of diffusion-weighted (DW) images was significantly associated with findings of either increased (DW ≥ 30) versus decreased (DW ≤ 25) anisotropic diffusion. Other clinical and experimental factors were not statistically significant for direction of anisotropic diffusion, but these results may have been limited by the relatively small number of studies within each domain (e.g., pediatric studies). In summary, current results indicate roughly equivalent number of studies reporting increased versus decreased anisotropic diffusion during semi-acute mTBI, with the number of unique diffusion images being statistically associated with the direction of findings.

Static and Dynamic Intrinsic Connectivity following Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common neurological disorder and is typically characterized by temporally limited cognitive impairment and emotional symptoms. Previous examinations of intrinsic resting state networks in mTBI have primarily focused on abnormalities in static functional connectivity, and deficits in dynamic functional connectivity have yet to be explored in this population. Resting-state data was collected on 48 semi-acute (mean = 14 days post-injury) mTBI patients and 48 matched healthy controls. A high-dimensional independent component analysis (N = 100) was utilized to parcellate intrinsic connectivity networks (ICN), with a priori hypotheses focusing on the default-mode network (DMN) and sub-cortical structures. Dynamic connectivity was characterized using a sliding window approach over 126 temporal epochs, with standard deviation serving as the primary outcome measure. Finally, distribution-corrected z-scores (DisCo-Z) were calculated to investigate changes in connectivity in a spatially invariant manner on a per-subject basis. Following appropriate correction for multiple comparisons, no significant group differences were evident on measures of static or dynamic connectivity within a priori ICN. Reduced (HC > mTBI patients) static connectivity was observed in the DMN at uncorrected (p < 0.005) thresholds. Finally, a trend (p = 0.07) for decreased dynamic connectivity in patients across all ICN was observed during spatially invariant analyses (DisCo-Z). In the semi-acute phase of recovery, mTBI was not reliably associated with abnormalities in static or dynamic functional connectivity within the DMN or sub-cortical structures.

A prospective biopsychosocial study of the persistent post-concussion symptoms following mild traumatic brain injury

This study examined multiple biopsychosocial factors relating to post-concussion symptom (PCS) reporting in patients with mild traumatic brain injuries (mTBI), including structural (computed tomography and magnetic resonance imaging [MRI]) and microstructural neuroimaging (diffusion tensor imaging [DTI]). Patients with mTBIs completed several questionnaires and cognitive testing at approximately one month (n=126) and one year (n=103) post-injury. At approximately three weeks post-injury, DTI was undertaken using a Siemens 3T scanner in a subgroup (n=71). Measures of fractional anisotropy were calculated for 16 regions of interest (ROIs) and measures of apparent diffusion coefficient were calculated for 10 ROIs. Patients were compared with healthy control subjects. Using International Classification of Diseases, Tenth Revision (ICD-10) PCS criteria and mild or greater symptom reporting, 59% of the mTBI sample met criteria at one month and 38% met criteria at one year. However, 31% of the healthy control sample also met criteria for the syndrome-illustrating a high false-positive rate. Significant predictors of ICD-10 PCS at one month were pre-injury mental health problems and the presence of extra-cranial bodily injuries. Being symptomatic at one month was a significant predictor of being symptomatic at one year, and depression was significantly related to PCS at both one month and one year. Intracranial abnormalities visible on MRI were present in 12.1% of this sample, and multifocal areas of unusual white matter as measured by DTI were present in 50.7% (compared with 12.4% of controls). Structural MRI abnormalities and microstructural white matter findings were not significantly associated with greater post-concussion symptom reporting. The personal experience and reporting of post-concussion symptoms is likely individualized, representing the cumulative effect of multiple variables, such as genetics, mental health history, current life stress, medical problems, chronic pain, depression, personality factors, and other psychosocial and environmental factors. The extent to which damage to the structure of the brain contributes to the persistence of post-concussion symptoms remains unclear.

Tonic and phasic alertness training: a novel treatment for executive control dysfunction following mild traumatic brain injury

Many individuals with traumatic brain injury (TBI) suffer difficulty regulating fundamental aspects of attention (focus, sustained attention) and may also exhibit hypo- or hyper-states of alertness. Deficits in the state of attention may underlie or exacerbate higher order executive dysfunction. Recent studies indicate that computerized cognitive training targeting attentional control and alertness can ameliorate attention deficits evident in patients with TBI or acquired brain injury. The current study examined whether improvements in attentional state following training can also influence performance on higher-order executive function and mood in individuals with mild TBI (mTBI). The current study examined five patients with executive control deficits as a result of mTBI, with or without persistent anxiety. Three patients engaged in ~5 hours of an executive control training task targeting inhibitory control and sustained attention; two additional patients were re-tested following the same period of time. Performance on standard neuropsychological measures of attention, executive function, and mood were evaluated pre- and post-training. The results indicate that tonic and phasic alertness training may improve higher-order executive function and mood regulation in individuals with TBI.

Dynamic testing of learning potential in adults with cognitive impairments: A systematic review of methodology and predictive value

Dynamic testing includes procedures that examine the effects of brief training on test performance where pre- to post-training change reflects patients' learning potential. The objective of this systematic review was to provide clinicians and researchers insight into the concept and methodology of dynamic testing and to explore its predictive validity in adult patients with cognitive impairments. The following electronic databases were searched: PubMed, PsychINFO, and Embase/Medline. Of 1141 potentially relevant articles, 24 studies met the inclusion criteria. The mean methodological quality score was 4.6 of 8. Eleven different dynamic tests were used. The majority of studies used dynamic versions of the Wisconsin Card Sorting Test. The training mostly consisted of a combination of performance feedback, reinforcement, expanded instruction, or strategy training. Learning potential was quantified using numerical (post-test score, difference score, gain score, regression residuals) and categorical (groups) indices. In five of six longitudinal studies, learning potential significantly predicted rehabilitation outcome. Three of four studies supported the added value of dynamic testing over conventional testing in predicting rehabilitation outcome. This review provides preliminary support that dynamic tests can provide a valuable addition to conventional tests to assess patients' abilities. Although promising, there was a large variability in methods used for dynamic testing and, therefore, it remains unclear which dynamic testing methods are most appropriate for patients with cognitive impairments. More research is warranted to further evaluate and refine dynamic testing methodology and to further elucidate its predictive validity concerning rehabilitation outcomes relative to other cognitive and functional status indices.

PTSD and TBI co-morbidity: scope, clinical presentation and treatment options

PRIMARY OBJECTIVE

To summarize the literature on post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI) and their co-morbidity, focusing on diagnosis, clinical symptoms and treatment issues relevant to the clinician.

RESEARCH DESIGN

Review of the literature.

METHODS AND PROCEDURES

Pubmed searches were performed using the terms post-traumatic stress disorder, traumatic brain injury, sleep, cognitive, depression, anxiety, treatment and combinations of these terms. Those articles relevant to the objective were included.

MAIN OUTCOMES AND RESULTS

This study presents pathophysiological, neuroimaging and clinical data on co-morbid PTSD and TBI. It reviews associated conditions, emphasizing the impact of cognitive and sleep problems. It summarizes the emerging literature on treatment effectiveness for co-morbid PTSD and TBI, including psychotherapy, pharmacotherapy and cognitive rehabilitation.

CONCLUSIONS

Both PTSD and TBI commonly occur in the general population, both share some pathophysiological characteristics and both are associated with cognitive impairment and sleep disruption. PTSD and TBI present with a number of overlapping symptoms, which can lead to over-diagnosis or misdiagnosis. Both conditions are associated with co-morbidities important in diagnosis and treatment planning. More research is needed to elucidate what treatments are effective in PTSD and TBI co-morbidity and on factors predictive of treatment success.

Exposure to sub-concussive head injury in boxing and other sports

BACKGROUND

Current characterizations of chronic traumatic brain injury (CTBI) in boxing, football and other sports are reviewed in the context of the history of research on sub-concussive brain trauma in athletes.

METHODS

The utility of exposure models for understanding CTBI in boxers is examined and concerns regarding the paucity of findings supportive of an exposure model for CTBI in football players are discussed.

RESULTS AND CONCLUSIONS

Recommendations for development of exposure models for sport-specific phenotypic characterizations of CTBI are presented.

Test validity and performance validity: considerations in providing a framework for development of an ability-focused neuropsychological test battery

Literature on test validity and performance validity is reviewed to propose a framework for specification of an ability-focused battery (AFB). Factor analysis supports six domains of ability: first, verbal symbolic; secondly, visuoperceptual and visuospatial judgment and problem solving; thirdly, sensorimotor skills; fourthly, attention/working memory; fifthly, processing speed; finally, learning and memory (which can be divided into verbal and visual subdomains). The AFB should include at least three measures for each of the six domains, selected based on various criteria for validity including sensitivity to presence of disorder, sensitivity to severity of disorder, correlation with important activities of daily living, and containing embedded/derived measures of performance validity. Criterion groups should include moderate and severe traumatic brain injury, and Alzheimer's disease. Validation groups should also include patients with left and right hemisphere stroke, to determine measures sensitive to lateralized cognitive impairment and so that the moderating effects of auditory comprehension impairment and neglect can be analyzed on AFB measures.

White matter integrity in veterans with mild traumatic brain injury: associations with executive function and loss of consciousness

OBJECTIVE

We investigated using diffusion tensor imaging (DTI) and the association between white matter integrity and executive function (EF) performance in postacute mild traumatic brain injury (mTBI). In addition, we examined whether injury severity, as measured by loss of consciousness (LOC) versus alterations in consciousness (AOC), is related to white matter microstructural alterations and neuropsychological outcome.

PARTICIPANTS

Thirty Iraq and Afghanistan War era veterans with a history of mTBI and 15 healthy veteran control participants.

RESULTS

There were no significant overall group differences between control and mTBI participants on DTI measures. However, a subgroup of mTBI participants with EF decrements (n = 13) demonstrated significantly decreased fractional anisotropy of prefrontal white matter, corpus callosum, and cingulum bundle structures compared with mTBI participants without EF decrements (n = 17) and control participants. Participants having mTBI with LOC were more likely to evidence reduced EF performances and disrupted ventral prefrontal white matter integrity when compared with either mTBI participants without LOC or control participants.

CONCLUSIONS

Findings suggest that altered white matter integrity contributes to reduced EF in subgroups of veterans with a history of mTBI and that LOC may be a risk factor for reduced EF as well as associated changes to ventral prefrontal white matter.

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.

Diagnostic accuracy studies in mild traumatic brain injury: a systematic review and descriptive analysis of published evidence

OBJECTIVES

To synthesize evidence and report findings from a systematic search and descriptive analysis of peer-reviewed published evidence of the accuracy of tests used for diagnosing mild traumatic brain injury (mTBI). The article also summarizes points of concurrence and divergence regarding case definitions of mTBI identified during the review. TYPE: Systematic review and descriptive analysis of published evidence.

LITERATURE SURVEY

A search of PubMed, PsychInfo, and the Cochrane Library for peer-reviewed publications between 1990 and July 6, 2011, identified 1218 abstracts; 277 articles were identified for full review, and 13 articles met the criteria for evaluation.

METHODOLOGY

Manuscript inclusion criteria were (1) reported sensitivity (Se) and specificity (Sp), or reported data were sufficient to compute Se and Sp; (2) >1 participant in the study; (3) at least 80% of the study cohort was ≥18 years of age; and (4) written in English. Articles describing clinical practice guidelines, opinions, theories, or clinical protocols were excluded. Seven investigators independently evaluated each article according to the Standards for Reporting of Diagnostic Accuracy (STARD) criteria.

SYNTHESIS

Findings indicate that all 13 studies involved civilian noncombat populations. In 7 studies, authors examined acute mTBI, and in 4 studies, historical remote mTBI was examined. In the 13 studies, Se ranged from 13%-92% and Sp ranged from 72%-99%, but confidence in these findings is problematic because the STARD review indicates opportunities for bias in each study.

CONCLUSIONS

Findings indicate that no well-defined definition or clinical diagnostic criteria exist for mTBI and that diagnostic accuracy is currently insufficient for discriminating between mTBI and co-occurring mental health conditions for acute and historic mTBI. Findings highlight the need for research examining the diagnostic accuracy for acute and historic mTBI.

Significant improvements in cognitive performance post-transcranial, red/near-infrared light-emitting diode treatments in chronic, mild traumatic brain injury: open-protocol study

This pilot, open-protocol study examined whether scalp application of red and near-infrared (NIR) light-emitting diodes (LED) could improve cognition in patients with chronic, mild traumatic brain injury (mTBI). Application of red/NIR light improves mitochondrial function (especially in hypoxic/compromised cells) promoting increased adenosine triphosphate (ATP) important for cellular metabolism. Nitric oxide is released locally, increasing regional cerebral blood flow. LED therapy is noninvasive, painless, and non-thermal (cleared by the United States Food and Drug Administration [FDA], an insignificant risk device). Eleven chronic, mTBI participants (26-62 years of age, 6 males) with nonpenetrating brain injury and persistent cognitive dysfunction were treated for 18 outpatient sessions (Monday, Wednesday, Friday, for 6 weeks), starting at 10 months to 8 years post- mTBI (motor vehicle accident [MVA] or sports-related; and one participant, improvised explosive device [IED] blast injury). Four had a history of multiple concussions. Each LED cluster head (5.35 cm diameter, 500 mW, 22.2 mW/cm(2)) was applied for 10 min to each of 11 scalp placements (13 J/cm(2)). LEDs were placed on the midline from front-to-back hairline; and bilaterally on frontal, parietal, and temporal areas. Neuropsychological testing was performed pre-LED, and at 1 week, and 1 and 2 months after the 18th treatment. A significant linear trend was observed for the effect of LED treatment over time for the Stroop test for Executive Function, Trial 3 inhibition (p=0.004); Stroop, Trial 4 inhibition switching (p=0.003); California Verbal Learning Test (CVLT)-II, Total Trials 1-5 (p=0.003); and CVLT-II, Long Delay Free Recall (p=0.006). Participants reported improved sleep, and fewer post-traumatic stress disorder (PTSD) symptoms, if present. Participants and family reported better ability to perform social, interpersonal, and occupational functions. These open-protocol data suggest that placebo-controlled studies are warranted.

Postconcussive symptom exaggeration after pediatric mild traumatic brain injury

BACKGROUND

A minority of pediatric patients who have mild traumatic brain injury (mTBI) report persistent postconcussive symptoms. In adults, failure on validity tests, which help to detect exaggerated or feigned problems, is associated with symptom complaints. No pediatric studies have examined the relationship between validity test performance and symptom report. We hypothesized that children failing a validity test would report significantly more postconcussive symptoms than those passing.

METHODS

Using a consecutive clinical case series design, we examined 191 patients aged 8 to 17 years seen for neuropsychological evaluation after mTBI. Participants were administered a validity test (Medical Symptom Validity Test; MSVT) and completed a graded symptom scale as part of a neuropsychological battery.

RESULTS

A total of 23 participants (12%) failed the MSVT. The Fail group endorsed significantly more postconcussive symptoms than the Pass group, with a large effect size (P < .001; d = 1.1). MSVT performance remained a robust unique predictor of symptom report even after controlling for other influential factors (eg, female gender, premorbid psychiatric problems).

CONCLUSIONS

A subset of children who had persistent complaints after mTBI may be exaggerating or feigning symptoms. If such negative response bias remains undetected, errors in etiologic statements and less than optimal treatment may occur. Because the detection of invalid responding is well established in neuropsychology, clinical neuropsychologists should be incorporated routinely into clinical care for patients who have persistent complaints. To better control for noninjury effects in future pediatric mTBI studies, researchers should add validity tests to neurobehavioral outcome batteries.

Changes in saccadic eye movement and memory function after mild closed head injury in children

AIM

The aim of this study was to determine whether volitional saccadic impairments are present in children with mild closed head injury (mCHI) and whether these deficits are predictive of ongoing cognitive impairment.

METHOD

We analysed a sample of 26 children with mCHI (20 males, 6 females; mean age 13y 1mo, SD 2y) and 29 age-matched comparison children (20 males, 9 females; mean age 12y 2mo, SD 2y). Participants completed a battery of saccadic eye movement tasks and a set of computer-based cognitive tasks at three time points: within 2 weeks of mCHI, and at 3 months and 6 months.

RESULTS

The group with mCHI made fewer errors on the antisaccade task at the first time point and showed increased latencies on prosaccades, correct antisaccades, and corrected antisaccade errors at the third time point (6mo). The group with mCHI also showed poorer performance on the cognitive tasks assessing memory.

INTERPRETATION

Even very mild, uncomplicated mCHI in children may persistently affect aspects of executive control and visual processing.

Cognitive sequelae of traumatic brain injury

Cognitive dysfunction is the leading cause of disability following traumatic brain injury (TBI). This article provides a review of the cognitive sequelae of TBI, with a focus on deficits of executive functioning and everyday thinking skills. The pathophysiology, assessment, and treatment of TBI-related cognitive problems are also discussed.

Predicting mild traumatic brain injury patients at risk of persistent symptoms in the Emergency Department

OBJECTIVE

To identify factors that can predict which emergency department (ED) patients with mTBI are likely to develop persistent post-concussion symptoms (PPCS).

DESIGN

A matched case-control study was conducted at a Level 1 trauma centre between June 2006 and July 2009. Patients diagnosed with mTBI in the ED and diagnosed at a concussion management programme with at least one PPCS (85 cases) were compared to patients diagnosed with mTBI in the ED (340 controls) to determine if factors assessed at the time of ED presentation could predict patients likely to develop persistent symptoms.

RESULTS

Multivariable hierarchical logistic regression with variables indicating increased risk for PPCS (prior mTBI, history of depression, history of anxiety, multiple injury, forgetfulness/poor memory, noise sensitivity, or light sensitivity) resulted in a final predictive model including prior mTBI, history of anxiety, forgetfulness/poor memory and light sensitivity. The final model had a specificity of 87.9% and a sensitivity of 69.9%.

CONCLUSIONS

A strong prediction model to identify those ED patients with mTBI at risk for PPCS was developed and could be easily implemented in the ED; therefore, helping to target those patients who would potentially benefit from close follow-up.

Athletes' age, sex, and years of education moderate the acute neuropsychological impact of sports-related concussion: a meta-analysis

The objective of this study is to determine which pre-existing athlete characteristics, if any, are associated with greater deficits in functioning following sports-related concussion, after controlling for factors previously shown to moderate this effect (e.g., time since injury). Ninety-one independent samples of concussion were included in a fixed+systematic effects meta-analysis (n = 3,801 concussed athletes; 5,631 controls). Moderating variables were assessed using analogue-to-ANOVA and meta-regression analyses. Post-injury assessments first conducted 1-10 days following sports-related concussion revealed significant neuropsychological dysfunction, postural instability and post-concussion symptom reporting (d = -0.54, -1.10, and -1.14, respectively). During this interval, females (d = -0.87), adolescent athletes competing in high school competitions (d = -0.60), and those with 10 years of education (d = -1.32) demonstrated larger post-concussion neuropsychological deficits than males (d = -0.42), adults (d = -0.25), athletes competing at other levels of competition (d = -0.43 to -0.41), or those with 16 years of education (d = -0.15), respectively. However, these sub-groups' differential impairment/recovery beyond 10 days could not be reliably quantified from available literature. Pre-existing athlete characteristics, particularly age, sex and education, were demonstrated to be significant modifiers of neuropsychological outcomes within 10 days of a sports-related concussion. Implications for return-to-play decision-making and future research directions are discussed.

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.