Exposure to repetitive head impacts (RHIs) in contact sports is associated with neurodegenerative disorders including chronic traumatic encephalopathy (CTE) which currently can be diagnosed only at postmortem. American football players are at higher risk of developing CTE given their exposure to RHIs. One promising approach for diagnosing CTE in vivo is to explore known neuropathological abnormalities at postmortem in living individuals using structural magnetic resonance imaging (MRI). MRI brain morphometry was evaluated in 170 male former American football players ages 45-74 years (n = 114 professional; n = 56 college) and 54 same-age unexposed asymptomatic male controls (n = 58 age range 45-74). Cortical thickness and volume of regions of interest were selected based on established CTE pathology findings and were assessed using FreeSurfer. Group differences and interactions with age and exposure factors were evaluated using a generalized least squares model. A separate logistic regression and independent multinomial model were performed to predict each Traumatic Encephalopathy Syndrome (TES) diagnosis core clinical features and provisional level of certainty for CTE pathology using brain regions of interest. Former college and professional American football players (combined) showed significant cortical thickness and/or volume reductions compared to unexposed asymptomatic controls in the hippocampus amygdala entorhinal cortex parahippocampal gyrus insula temporal pole and superior frontal gyrus. Post-hoc analyses identified group-level differences between former professional players and unexposed asymptomatic controls in the hippocampus amygdala entorhinal cortex parahippocampal gyrus insula and superior frontal gyrus. Former college players showed significant volume reductions in the hippocampus amygdala and superior frontal gyrus compared to the unexposed asymptomatic controls. We did not observe age-by-group interactions for brain morphometric measures. Interactions between morphometry and exposure measures were limited to a single significant positive association between the age of first exposure to organized tackle football and right insular volume. We found no significant relationship between brain morphometric measures and the TES diagnosis core clinical features and provisional level of certainty for CTE pathology outcomes. These findings suggest that MRI morphometrics detects abnormalities in individuals with a history of RHI exposure that resemble the anatomic distribution of pathological findings from postmortem CTE studies. The lack of findings associating MRI measures with exposure metrics (except for one significant relationship) or TES diagnosis and core clinical features suggests that brain morphometry must be complemented by other types of measures to characterize individuals with RHIs.

中文翻译：

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前美国橄榄球运动员的大脑形态测量：DIAGNOSE CTE 研究项目的发现

在接触运动中遭受重复性头部撞击（RHI）与神经退行性疾病有关，包括慢性创伤性脑病（CTE），目前只能在死后诊断。鉴于美国橄榄球运动员接触 RHI，他们患 CTE 的风险更高。体内诊断 CTE 的一种有前景的方法是使用结构磁共振成像 (MRI) 来探索活体死后已知的神经病理学异常。对 170 名年龄 45-74 岁的前美国橄榄球运动员（n = 114 名职业球员；n = 56 名大学生）和 54 名同龄未暴露的无症状男性对照者（n = 58 名年龄范围 45-74 岁）进行了 MRI 脑形态测量评估。根据已建立的 CTE 病理学结果选择感兴趣区域的皮质厚度和体积，并使用 FreeSurfer 进行评估。使用广义最小二乘模型评估组差异以及与年龄和暴露因素的相互作用。使用感兴趣的大脑区域进行单独的逻辑回归和独立多项模型来预测每个创伤性脑病综合征 (TES) 诊断的核心临床特征和 CTE 病理学的临时确定性水平。与未暴露的无症状对照组相比，前大学和职业美国橄榄球运动员（合并）的海马杏仁核、内嗅皮质、海马旁回、岛颞极和额上回的皮质厚度和/或体积显着减少。事后分析确定了前职业球员和未暴露的无症状对照组之间海马杏仁核、内嗅皮层、海马旁岛回和额上回的群体水平差异。与未暴露的无症状对照组相比，前大学球员的海马杏仁核和额上回体积显着减少。我们没有观察到大脑形态测量中年龄组之间的相互作用。形态测定和暴露测量之间的相互作用仅限于首次接触有组织的橄榄球比赛的年龄和右岛体积之间的单一显着正相关。我们发现大脑形态测量与 TES 诊断核心临床特征以及 CTE 病理结果的临时确定性水平之间没有显着关系。这些发现表明，MRI 形态计量学可以检测到有 RHI 暴露史的个体的异常情况，这些异常情况类似于死后 CTE 研究中病理结果的解剖分布。缺乏将 MRI 测量与暴露指标（除了一种显着关系）或 TES 诊断和核心临床特征相关联的发现表明，大脑形态测量必须辅以其他类型的测量来表征 RHI 个体。