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.