NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Unité de Neuroimagerie Fonctionnelle (UNF), Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montreal, QC, Canada; Department of Neurosciences, Faculty of Medicine, Université de Montréal, QC, Canada.
Unité de Neuroimagerie Fonctionnelle (UNF), Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montreal, QC, Canada; Department of Biomedical Sciences, Faculty of Medicine, Université de Montréal, QC, Canada.
Neuroimage. 2019 Feb 1;186:577-585. doi: 10.1016/j.neuroimage.2018.11.015. Epub 2018 Nov 16.
The stiffness of large arteries and increased pulsatility can have an impact on the brain white matter (WM) microstructure, however those mechanisms are still poorly understood. The aim of this study was to investigate the association between central artery stiffness, axonal and myelin integrity in 54 cognitively unimpaired elderly subjects (65-75 years old).
The neuronal fiber integrity of brain WM was assessed using diffusion tensor metrics and magnetization transfer imaging as measures of axonal organization (Fractional anisotropy, Radial diffusivity) and state of myelination (Myelin volume fraction). Central artery stiffness was measured by carotid-femoral pulse wave velocity (cfPWV). Statistical analyses included 4 regions (the corpus callosum, the internal capsule, the corona radiata and the superior longitudinal fasciculus) which have been previously denoted as vulnerable to increased central artery stiffness.
cfPWV was significantly associated with fractional anisotropy and radial diffusivity (p < 0.05, corrected for multiple comparisons) but not with myelin volume fraction. Findings from this study also show that improved executive function performance correlates with Fractional anisotropy positively (p < 0.05 corrected) as well as with myelin volume fraction and radial diffusivity negatively (p < 0.05 corrected).
These findings suggest that arterial stiffness is associated with axon degeneration rather than demyelination. Controlling arterial stiffness may play a role in maintaining the health of WM axons in the aging brain.
大动脉僵硬和脉动性增加会对脑白质（WM）的微观结构产生影响，但这些机制仍知之甚少。本研究旨在调查 54 名认知正常的老年受试者（65-75 岁）的中央动脉僵硬、轴突和髓鞘完整性之间的关联。
使用弥散张量指标和磁化传递成像评估脑 WM 的神经元纤维完整性，作为轴突组织（各向异性分数、径向弥散度）和髓鞘状态（髓鞘体积分数）的测量指标。通过颈股脉搏波速度（cfPWV）测量中央动脉僵硬。统计分析包括 4 个区域（胼胝体、内囊、放射冠和上纵束），这些区域以前被认为易受中央动脉僵硬增加的影响。
cfPWV 与各向异性分数和径向弥散度显著相关（p<0.05，经多重比较校正），但与髓鞘体积分数无关。本研究的结果还表明，执行功能的改善与各向异性分数呈正相关（经校正 p<0.05），与髓鞘体积分数和径向弥散度呈负相关（经校正 p<0.05）。
这些发现表明，动脉僵硬与轴突退化而不是脱髓鞘有关。控制动脉僵硬可能在维持老年大脑 WM 轴突的健康方面发挥作用。
