APOE-ε4 Is Associated With Reduced Verbal Memory Performance and Higher Emotional, Cognitive, and Everyday Executive Function Symptoms Two Months After Mild Traumatic Brain Injury.

BACKGROUND: Substantial variance exists in outcomes after mild traumatic brain injury (MTBI), and these differences are not fully explained by injury characteristics or severity. Genetic factors are likely to play a role in this variance. OBJECTIVES: The aim of this study was to examine associations between the apolipoprotein (APOE)-ε4 allele and memory measures at two months post-MTBI and to evaluate whether subjective cognitive and affective symptoms were associated with APOE-ε4 status. Based on previous research, it was hypothesized that APOE-ε4 carriers would show poorer verbal memory performance compared to APOE-ε4 non-carriers. METHODS: Neuropsychological data at two months post-injury and blood samples that could be used to assess APOE genotype were available for 134 patients with MTBI (mean age 39.2 years, 62% males, 37% APOE-ε4 carriers). All patients underwent computed tomography at hospital admission and magnetic resonance imaging four weeks post-injury. RESULTS: The APOE-ε4 + status was associated with decreased immediate memory recall (p = 0.036; ß = -0.10, 95% CI [-0.19, -0.01]). Emotional, cognitive, and everyday executive function symptoms at two months post-injury were significantly higher in APOE-ε4 carriers compared to non-carriers. CONCLUSION: The APOE-ε4+ allele has a negative effect on verbal memory and symptom burden two months after MTBI.

Return to work after severe traumatic brain injury: a national study with a one-year follow-up of neurocognitive and behavioural outcomes.

The objectives were to investigate the frequency of return-to-work (RTW) one year after severe traumatic brain injury (sTBI: Glasgow Coma Scale, GCS 3-8) and to identify which demographic and injury-related characteristics and neurocognitive factors are associated with RTW. This study is part of a prospective national study on sTBI conducted in all four Norwegian Trauma Referral Centres, including patients aged >15 years over a period of three years (n = 378). For the purpose of this study, only pre-employed individuals of working age (16 to 67 years) were investigated for RTW (n = 143), and of these, 104 participants underwent neuropsychological testing. Measures of acute injury severity, neuropsychological composite scores (Memory, Processing Speed, Executive Functions) at the one-year follow-up, and the Behaviour Rating Inventory of Executive Functions (patient- and relative reports) were explored as predictors of RTW. The frequency of RTW was 54.5%. Multivariate logistic regression analyses identified younger age, shorter length of stay in intensive care, better Processing Speed scores, and lower levels of metacognitive difficulties as rated by relatives as significant predictors of RTW. Findings support the importance of neuropsychological measures in predicting long-term RTW and highlight the need to address neurocognitive and behavioural difficulties to improve RTW after sTBI.

Improvement and Prediction of Memory and Executive Functions in Patients Admitted to a Neurosurgery Service With Complicated and Uncomplicated Mild Traumatic Brain Injury.

OBJECTIVES: To compare neuropsychological performances between patients with and without intracranial abnormalities after mild traumatic brain injury (mTBI) and assess the relationship between demographics, injury severity, and self-reported symptom characteristics with improvements in memory and executive functions (8 weeks to 1 year postinjury). SETTING: Inpatient/outpatient followed up at the Department of Physical Medicine and Rehabilitation, Oslo, Norway. PARTICIPANTS: Patients were divided into groups of complicated (n = 73) or uncomplicated mTBIs (n = 77) based on intracranial findings on computed tomographic or magnetic resonance imaging brain scans. DESIGN: Prospective, longitudinal cohort study. MAIN MEASURES: Neuropsychological assessments of memory and executive functions, self-reports of postconcussion, depression, posttraumatic stress symptoms, and general functioning at 8 weeks and 1 year postinjury. RESULTS: Longitudinal data showed that patients with complicated and uncomplicated mTBIs had similar cognitive performance and improvements. Hierarchical linear modeling revealed that individuals with early posttraumatic stress disorder and/or depressive symptoms performed worse on measures of Memory functions, and those with younger age (<40 years) and lower education (<12 years) performed worse on measures of Executive functions. CONCLUSION: Findings are suggestive of a good cognitive outcome following complicated and uncomplicated mTBIs. Early assessments of posttraumatic stress disorder and depression seem useful in identifying those most vulnerable having poorer cognitive outcomes, providing further interventions that may affect emotional and cognitive recovery.

Olfactory identification and its relationship to executive functions, memory, and disability one year after severe traumatic brain injury.

OBJECTIVE: To explore the frequency of posttraumatic olfactory (dys)function 1 year after severe traumatic brain injury (TBI) and determine whether there is a relationship between olfactory identification and neuropsychological test performance, injury severity and TBI-related disability. METHOD: A population-based multicenter study including 129 individuals with severe TBI (99 males; 16 to 85 years of age) that could accomplish neuropsychological examinations. Olfactory (dys)function (anosmia, hyposmia, normosmia) was assessed by the University of Pennsylvania Smell Identification Test (UPSIT) or the Brief Smell Identification Test (B-SIT). Three tests of the Delis-Kaplan Executive Function System (D-KEFS) were used to assess processing speed, verbal fluency, inhibition and set-shifting, and the California Verbal Learning Test-II was used to examine verbal memory. The Glasgow Outcome Scale-Extended (GOSE) was used to measure disability level. RESULTS: Employing 2 different smell tests in 2 equal-sized subsamples, the UPSIT sample (n = 65) classified 34% with anosmia and 52% with hyposmia, while the B-SIT sample (n = 64) classified 20% with anosmia and 9% with hyposmia. Individuals classified with anosmia by the B-SIT showed significantly lower scores for set-shifting, category switching fluency and delayed verbal memory compared to hyposmia and normosmia groups. Only the B-SIT scores were significantly correlated with neuropsychological performance and GOSE scores. Brain injury severity (Rotterdam CT score) and subarachnoid hemorrhage were related to anosmia. Individuals classified with anosmia demonstrated similar disability as those with hyposmia/normosmia. CONCLUSIONS: Different measures of olfaction may yield different estimates of anosmia. Nevertheless, around 1 third of individuals with severe TBI suffered from anosmia, which may also indicate poorer cognitive outcome.