Background Myelin loss and cerebral blood flow (CBF) decline are central features of several neurodegenerative diseases. Myelin maintenance through oligodendrocyte metabolism is an energy-demanding process, so that myelin homeostasis is particularly sensitive to hypoxia, hypoperfusion or ischaemia. However, in spite of its central importance, little is known about the association between blood supply and myelin integrity. Objective To assess associations between cortical and subcortical CBF, and subcortical myelin content, in critical brain white matter regions. Materials and methods MRI was performed on a cohort of 67 cognitively unimpaired adults. Using advanced MRI methodology, we measured whole-brain longitudinal and transverse relaxation rates ( R1 and R2 ), sensitive but non-specific markers of myelin content, and myelin water fraction (MWF), a direct surrogate of myelin content, as well as regional CBF, from each of these participants. Results All quantitative relaxometry metrics were positively associated with CBF in all brain regions evaluated. These associations between MWF or R1 and CBF, and, to a lesser extent, between R2 and CBF, were statistically significant in most brain regions examined, indicating that lower regional cortical or subcortical CBF corresponds to a decrease in local subcortical myelin content. Finally, all relaxometry metrics exhibited a quadratic, inverted U-shaped, association with age; this is attributed to the development of myelination from young to middle age, followed by progressive loss of myelin in later years. Conclusions In this first study examining the association between local blood supply and myelin integrity, we found that myelin content declines with CBF across a wide age range of cognitively normal subjects.

中文翻译：

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认知未受损成人脑血流量与髓磷脂含量的关系

背景髓鞘损失和脑血流量 (CBF) 下降是几种神经退行性疾病的核心特征。通过少突胶质细胞代谢维持髓鞘是一个需要能量的过程，因此髓鞘稳态对缺氧、低灌注或缺血特别敏感。然而，尽管它具有核心重要性，但人们对血液供应与髓鞘完整性之间的关联知之甚少。目的 评估关键脑白质区域皮质和皮质下 CBF 以及皮质下髓鞘含量之间的关联。材料和方法 对 67 名认知正常的成年人进行 MRI 检查。使用先进的 MRI 方法，我们测量了全脑纵向和横向松弛率（R1 和 R2）、髓磷脂含量的敏感但非特异性标志物和髓磷脂水分数 (MWF)，来自这些参与者中的每一个的髓磷脂含量以及区域CBF的直接替代物。结果在所有评估的大脑区域中，所有定量松弛测量指标都与 CBF 呈正相关。MWF 或 R1 和 CBF 之间的这些关联，以及在较小程度上，R2 和 CBF 之间的这些关联，在检查的大多数大脑区域中具有统计学意义，表明较低的区域皮质或皮质下 CBF 对应于局部皮质下髓鞘含量的减少。最后，所有的弛豫测量指标都与年龄呈二次倒 U 形相关；这归因于从年轻到中年的髓鞘形成，随后在晚年逐渐丧失髓鞘。结论 在第一项研究局部血液供应与髓鞘完整性之间的关系的研究中，