BackgroundMild traumatic brain injury (MTBI) is a frequent medical condition, and some patients report long-lasting problems after MTBI. In order to prevent MTBI, knowledge of the epidemiology is important and potential bias in studies should be explored.Aims of this study were to describe the epidemiological characteristics of MTBI in a Norwegian area and to evaluate the representativeness of patients successfully enrolled in the Trondheim MTBI follow-up study.MethodsDuring 81 weeks in 2014 and 2015, all persons aged 16–60 years, presenting with possible MTBI to the emergency department (ED) at St. Olavs Hospital, Trondheim University Hospital or to Trondheim municipal outpatient ED, were evaluated for participation in the follow-up study. Patients were identified by CT referrals and patient lists. Patients who were excluded or missed for enrolment in the follow-up study were recorded.ResultsWe identified 732 patients with MTBI. Median age was 28 years, and fall was the most common cause of injury. Fifty-three percent of injuries occurred during the weekend. Only 29% of MTBI patients were hospitalised. Study specific exclusion criteria were present in 23%. We enrolled 379 in the Trondheim MTBI follow-up study. In this cohort, Glasgow Coma Scale score was 15 at presentation in 73%; 45% of patients were injured under the influence of alcohol. Patients missed for inclusion were significantly more often outpatients, females, injured during the weekend, and suffering violent injuries, but differences between enrolled and not enrolled patients were small.ConclusionTwo thirds of all patients with MTBI in the 16–60 age group were treated without hospital admission, patients were often young, and half of the patients presented during the weekend. Fall was the most common cause of injury, and patients were commonly injured under the influence of alcohol, which needs to be addressed when considering strategies for prevention. The Trondheim MTBI follow-up study comprised patients who were highly representative for the underlying epidemiology of MTBI.

Aims of this study were to investigate white matter (WM) and thalamus microstructure 72 hr and 3 months after mild traumatic brain injury (TBI) with diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI), and to relate DKI and DTI findings to postconcussional syndrome (PCS). Twenty‐five patients (72 hr = 24; 3 months = 23) and 22 healthy controls were recruited, and DKI and DTI data were analyzed with Tract‐Based Spatial Statistics (TBSS) and a region‐of‐interest (ROI) approach. Patients were categorized into PCS or non‐PCS 3 months after injury according to the ICD‐10 research criteria for PCS. In TBSS analysis, significant differences between patients and controls were seen in WM, both in the acute stage and 3 months after injury. Fractional anisotropy (FA) reductions were more widespread than kurtosis fractional anisotropy (KFA) reductions in the acute stage, while KFA reductions were more widespread than the FA reductions at 3 months, indicating the complementary roles of DKI and DTI. When comparing patients with PCS ( n = 9), without PCS ( n = 16), and healthy controls, in the ROI analyses, no differences were found in the acute DKI and DTI metrics. However, near‐significant differences were observed for several DKI metrics obtained in WM and thalamus concurrently with symptom assessment (3 months after injury). Our findings indicate a combined utility of DKI and DTI in detecting WM microstructural alterations after mild TBI. Moreover, PCS may be associated with evolving alterations in brain microstructure, and DKI may be a promising tool to detect such changes.

The Cambridge Neuropsychological Test Automated Battery (CANTAB) is a battery of computerized neuropsychological tests commonly used in Europe in neurology and psychiatry studies, including clinical trials. The purpose of this study was to investigate test-retest reliability and to develop reliable change indices and regression-based change formulas for using the CANTAB in research and practice involving repeated measurement. A sample of 75 healthy adults completed nine CANTAB tests, assessing three domains (i.e., visual learning and memory, executive function, and visual attention) twice over a 3-month period. Wilcoxon signed-rank tests showed significant practice effects for 6 of 14 outcome measures with effect sizes ranging from negligible to medium (Hedge's g: .15-.40; Cliff's delta: .09-.39). The Spatial Working Memory test, Attention Switching Task, and Rapid Visual Processing test were the only tests with scores of adequate test-retest reliability. For all outcome measures, Pearson's and Spearman's correlation coefficients ranged from .39 to .79. The measurement error surrounding difference scores was large, thus requiring large changes in performance (i.e., 1-2 SDs) in order to interpret a change score as reliable. In the regression equations, test scores from initial testing significantly predicted retest scores for all outcome measures. Age was a significant predictor in several of the equations, while education was a significant predictor in only two of the equations. The adjusted R 2 values ranged between .19 and .67. The present study provides results enabling clinicians to make probabilistic statements about change in cognitive functions based on CANTAB test performances.

To investigate whether cognitive reserve moderates differences in cognitive functioning between patients with mild traumatic brain injury (MTBI) and controls without MTBI and to examine whether patients with postconcussion syndrome have lower cognitive functioning than patients without postconcussion syndrome at 2 weeks and 3 months after injury. Design: Trondheim MTBI follow-up study is a longitudinal controlled cohort study with cognitive assessments 2 weeks and 3 months after injury. Setting: Recruitment at a level 1 trauma center and at a general practitioner-run, outpatient clinic. Participants: Patients with MTBI (nZ160) according to the World Health Organization criteria, trauma controls (nZ71), and community controls (nZ79) (NZ310). Main Outcome Measures: A cognitive composite score was used as outcome measure. The Vocabulary subtest was used as a proxy of cognitive reserve. Postconcussion syndrome diagnosis was assessed at 3 months with the British Columbia Postconcussion Symptom Inventory. Results: Linear mixed models demonstrated that the effect of vocabulary scores on the cognitive composite scores was larger in patients with MTBI than in community controls at 2 weeks and at 3 months after injury (PZ.001). Thus, group differences in the cognitive composite score varied as a function of vocabulary scores, with the biggest differences seen among participants with lower vocabulary scores. There were no significant differences in the cognitive composite score between patients with (nZ29) and without (nZ131) postconcussion syndrome at 2 weeks or 3 months after injury. Conclusion: Cognitive reserve, but not postconcussion syndrome, was associated with cognitive outcome after MTBI. This supports the cognitive reserve hypothesis in the MTBI context and suggests that persons with low cognitive reserve are morevulnerable to reduced cognitive functioning if they sustain an MTBI.

This study investigates subacute cognitive effects of mild traumatic brain injury (MTBI) in the Trondheim Mild TBI Study, as measured, in part, by the neuropsychological test battery of the Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) program, including computerized tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and traditional paper-and-pencil tests. We investigated whether cognitive function was associated with injury severity: intracranial traumatic lesions on neuroimaging, witnessed loss of consciousness (LOC), or post-traumatic amnesia (PTA) >1 h. Further, we explored which of the tests in the CENTER-TBI battery might be associated with the largest subacute effects of MTBI (i.e., at 2 weeks postinjury). We recruited 177 patients with MTBI (16-59 years of age) from a regional trauma center and an outpatient clinic,79 trauma control participants, and 81 community control participants. The MTBI group differed from community controls only on one traditional test of processing speed (coding; p = 0.009, Cliff's delta [D] = 0.20). Patients with intracranial abnormalities performed worse than those without on a traditional test (phonemic verbal fluency; p = 0.043, D = 0.27), and patients with LOC performed differently on the Attention Switching Task from the CANTAB (p = 0.020, D =-0.20). Patients with PTA >1 h performed worse than those with <1 h on 10 measures, from traditional tests and the CANTAB (D = 0.33-0.20), likely attributable, at least in part, to pre-existing differences in intellectual functioning between groups. In general, those with MTBI had good neuropsychological outcome 2 weeks after injury and no particular CENTER-TBI computerized or traditional tests seemed to be more sensitive to subtle cognitive deficits.

Objective: Seven candidate cognition composite scores have been developed and evaluated as part of a research program designed to validate a cognition endpoint for traumatic brain injury (TBI) research and clinical trials, but these composites have yet to be examined longitudinally. This study examined test-retest reliability and methods for determining reliable change for these seven candidate composite scores, using the neuropsychological test battery from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI).Methods: Participants (18-59 years-old) with mild TBI (n = 124), orthopedic trauma without head injury (n = 67), and healthy community controls (n = 63) from the Trondheim MTBI follow-up study completed the CENTER-TBI neuropsychological test battery at 2 weeks and 3 months after injury. The battery included both traditional paper-and-pencil tests and computerized tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Seven composite scores were calculated for the paper-and-pencil tests, the CANTAB tests, and all tests combined (i.e., 21 composites in total on each assessment): the overall test battery mean (OTBM); global deficit score (GDS); neuropsychological deficit score-weighted (NDS-W); low score composite (LSC); and the number of scores ≤5th percentile, ≤16th percentile, or <50th percentile. The OTBM was calculated by averaging T scores for all tests. The other composite scores were deficit-based scores, assigning different weights to low scores.Results: All composites revealed better cognitive performance at the 3-month assessment compared to the 2-week assessment and the magnitude of improvement was similar across groups. Differences, in terms of effect sizes, were largest on the OTBMs. In the combined composites, the test-retest correlation was highest for the Stenberg et al.Cognition Endpoints-Test-Retest OTBM (Spearman's rho = 0.87, in the community control group) and lowest for the number of scores ≤5th percentile (rho = 0.41). Conclusion:The high test-retest reliability of the OTBM appears to favor its use in TBI research; however, future studies are needed to examine these candidate composite scores in participants with more severe TBIs and cognitive deficits and the association of the composites with functional outcomes.

Objective This study examined cognitive functioning at approximately two weeks following mild traumatic brain injury (MTBI) and explored whether tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) revealed greater differences between patients with MTBI and controls than traditional neuropsychological tests. Method Patients with MTBIs (n = 177) according to the World Health Organization criteria, trauma controls with orthopedic injuries (n = 79), and community controls (n = 81) were assessed with 18 neuropsychological tests an average of 17 days post injury (SD = 3 days). The tests consisted of both traditional, well-established, paper and pencil tests (9 tests, 11 outcome measures) and tests from the CANTAB battery (9 tests, 14 outcome measures). Results Of the 25 outcome measures, the groups only differed significantly on the Coding subtest from the WAIS-IV battery (uncorrected Kruskal-Wallis test: p = 0.025), with lower performance in the MTBI group compared to the community control group (Cliff’s delta = -0.20). Effect sizes of the differences between patients with MTBI and community controls ranged from -0.16 to 0.01 on the CANTAB tests and -0.20 to 0.00 on the traditional tests. Effect sizes of the differences between patients with MTBI and trauma controls ranged from -0.13 to 0.06 on the CANTAB tests and -0.15 to 0.02 on the traditional tests. Conclusions Patients with MTBI did not have significantly lower cognitive test performance than trauma controls or community controls on a large number of tests two weeks after injury. Further, differences between patients with MTBI and controls were similar for the CANTAB battery and traditional tests.