Journal of neurotrauma
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Journal of neurotrauma · Feb 2017
Genetics and Other Risk Factors for Past Concussions in Active-Duty Soldiers.
Risk factors for concussion in active-duty military service members are poorly understood. The present study examined the association between self-reported concussion history and genetics (apolipoprotein E [APOE], brain-derived neurotrophic factor [BDNF], and D2 dopamine receptor genes [DRD2]), trait personality measures (impulsive-sensation seeking and trait aggression-hostility), and current alcohol use. The sample included 458 soldiers who were preparing to deploy for Operation Iraqi Freedom/Operation Enduring Freedom. ⋯ Those with the BDNF Met/Met genotype also reported greater aggression and hostility personality characteristics. When combined in a predictive model, prior military deployments, being male, and having the BDNF Met/Met genotype were independently associated with increased lifetime history of concussions in active-duty soldiers. Replication in larger independent samples is necessary to have more confidence in both the positive and negative genetic associations reported in this study.
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Journal of neurotrauma · Feb 2017
Brain structure and function associated with a history of sport concussion: a multi-modal MRI study.
There is growing concern about the potential long-term consequences of sport concussion for young, currently active athletes. However, there remains limited information about brain abnormalities associated with a history of concussion and how they relate to clinical factors. In this study, advanced MRI was used to comprehensively describe abnormalities in brain structure and function associated with a history of sport concussion. ⋯ White matter showed limited correlations with clinical factors, predominantly in the anterior corona radiata. This study provides the first evidence of the long-term effects of concussion on gray matter volume, blood flow, and white matter microstructure within a single athlete cohort. This was examined for a mixture of male and female athletes in both contact and noncontact sports, demonstrating the relevance of these findings for the overall sporting community.
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Journal of neurotrauma · Feb 2017
Abnormalities in functional connectivity in collegiate football athletes with and without a concussion history: implications and role of neuroactive kynurenine pathway metabolites.
There is a great need to identify potential long-term consequences of contact sport exposure and to identify molecular pathways that may be associated with these changes. We tested the hypothesis that football players with (Ath-mTBI) (n = 25) and without a concussion history (Ath) (n = 24) have altered resting state functional connectivity in regions with previously documented structural changes relative to healthy controls without football or concussion history (HC) (n = 27). As a secondary aim, we tested the hypothesis that group differences in functional connectivity are moderated by the relative ratio of neuroprotective to neurotoxic metabolites of the kynurenine pathway. ⋯ In contrast, both Ath-mTBI and Ath had increased connectivity between the left orbital frontal cortex and the right lateral frontal cortex, and between the left cornu ammonis areas 2 and 3/dentate gyrus (CA2-3/DG) of the hippocampus and the middle and posterior cingulate cortices, relative to HC. The relationship between the ratio of plasma concentrations of kynurenic acid to quinolinic acid (KYNA/QUIN) and left pregenual anterior cingulate cortex connectivity to multiple regions as well as KYNA/QUIN and right CA2-3/DG connectivity to multiple regions differed significantly according to football and concussion history. The results suggest that football exposure with and without concussion history can have a significant effect on intrinsic brain connectivity and implicate the kynurenine metabolic pathway as one potential moderator of functional connectivity dependent on football exposure and concussion history.
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Journal of neurotrauma · Feb 2017
Olfactory Function and Associated Clinical Correlates in Former NFL Players.
Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. ⋯ In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction.
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Journal of neurotrauma · Feb 2017
Memantine reduced cell death, astrogliosis, and functional deficits in an in vitro model of repetitive mild traumatic brain injury.
Clinical studies suggest that athletes with a history of concussion may be at risk for additional mild traumatic brain injury (mTBI), and repetitive exposure to mTBI acutely increases risk for more significant and persistent symptoms and increases future risk for developing neurodegenerative diseases. Currently, symptoms of mTBI are managed with rest and pain medication; there are no drugs approved by the Food and Drug Administration (FDA) that target the biochemical pathology underlying mTBI to treat or prevent acute and long-term effects of repetitive mTBI. Memantine is an FDA-approved drug for treating Alzheimer's disease, and also was shown to be neuroprotective in rodents following a single, moderate to severe TBI. ⋯ Samples received two injuries 24 h apart; injury resulted in significant cell death, loss of long-term potentiation (LTP), and astrogliosis compared with naïve, uninjured samples. Delivery of 1.5 μM memantine 1 h following each stretch significantly reduced the effect of injury for all outcome measures, and did not alter those outcome measures that were unaffected by the injury. Therefore, memantine warrants further pre-clinical and clinical investigation for its therapeutic efficacy to prevent cognitive deficits and neuropathology from multiple mTBIs.