Fatigability is prevalent in older adults. However, it is often associated with depressed mood. We aim to investigate these two psychobehavioral constructs by examining their underpinning of white matter structures in the brain and their associations with different medical conditions. Twenty-seven older adults with late-life depression (LLD) and 34 cognitively normal controls (CN) underwent multi-shell diffusion MRI. Fatigability was measured with the Pittsburgh Fatigability Scale. We examined white matter integrity by measuring the quantitative anisotropy (QA), a fiber tracking parameter with better accuracy than the traditional imaging technique. We found those with LLD had lower QA in the 2nd branch of the left superior longitudinal fasciculus (SLF-II), and those with more physical fatigability had lower QA in more widespread brain regions. In tracts associated with more physical fatigability, the lower QA in left acoustic radiation and left superior thalamic radiation correlated with higher blood glucose ( = - 0.46 and - 0.49). In tracts associated with depression, lower QA in left SLF-II correlated with higher bilirubin level ( = - 0.58). Depression and fatigability were associated with various white matter integrity changes, which correlated with biochemistry biomarkers all related to inflammation.

中文翻译：

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老年人抑郁和身体疲劳感与白质完整性的关系

疲劳在老年人中普遍存在。然而，它往往与抑郁情绪有关。我们的目标是通过检查大脑白质结构的基础及其与不同医疗状况的关联来研究这两种心理行为结构。 27 名患有晚年抑郁症 (LLD) 的老年人和 34 名认知正常对照 (CN) 接受了多壳扩散 MRI。疲劳度用匹兹堡疲劳量表测量。我们通过测量定量各向异性 (QA) 来检查白质完整性，这是一种比传统成像技术更准确的纤维跟踪参数。我们发现患有 LLD 的人左上纵束第二分支 (SLF-II) 的 QA 较低，而身体易疲劳的人在更广泛的大脑区域的 QA 较低。在与更多身体疲劳相关的束中，左声辐射和左上丘脑辐射的 QA 较低与较高的血糖相关（= - 0.46 和 - 0.49）。在与抑郁相关的神经束中，左侧 SLF-II 的 QA 较低与较高的胆红素水平相关 (= - 0.58)。抑郁和疲劳与各种白质完整性变化有关，这些变化与所有与炎症相关的生化生物标志物相关。