Medical Imaging Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway; PET Center, University Hospital North Norway, Tromsø, Norway.
Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
Neuroimage. 2019 Dec;203:116158. doi: 10.1016/j.neuroimage.2019.116158. Epub 2019 Sep 4.
Even though age-related white matter hyperintensities (WMH) begin to emerge in middle age, their effect on brain micro- and macrostructure in this age group is not fully elucidated. We have examined how presence of WMH and load of WMH affect regional brain volumes and microstructure in a validated, representative general population sample of 873 individuals between 50 and 66 years. Presence of WMH was determined as Fazakas grade ≥1. WMH load was WMH volume from manual tracing of WMHs divided on intracranial volume. The impact of age appropriate WMH (Fazakas grade 1) on the brain was also investigated. Major novel findings were that even the age appropriate WMH group had widespread macro- and microstructural changes in gray and white matter, showing that the mere presence of WMH, not just WMH load is an important clinical indicator of brain health. With increasing WMH load, structural changes spread centrifugally. Further, we found three major patterns of FA and MD changes related to increasing WMH load, demonstrating a heterogeneous effect on white matter microstructure, where distinct patterns were found in the proximity of the lesions, in deep white matter and in white matter near the cortex. This study also raises several questions about the onset of WMH related pathology, in particular, whether some of the aberrant brain structural and microstructural findings are present before the emergence of WMH. We also found, similar to other studies, that WMH risk factors had low explanatory power for WMH, making it unclear which factors lead to WMH.
尽管与年龄相关的脑白质高信号（WMH）在中年开始出现，但它们在该年龄段对大脑微观和宏观结构的影响尚未完全阐明。我们研究了在一个经过验证的、具有代表性的 50 至 66 岁普通人群样本中，WMH 的存在及其负荷如何影响区域脑容量和微观结构。WMH 的存在通过 Fazakas 分级≥1 来确定。WMH 负荷是通过手动追踪 WMH 并将其除以颅内体积来计算的。我们还研究了年龄适宜的 WMH（Fazakas 分级 1）对大脑的影响。主要的新发现是，即使是年龄适宜的 WMH 组，在灰质和白质中也存在广泛的宏观和微观结构变化，这表明 WMH 的存在，而不仅仅是 WMH 的负荷，是大脑健康的一个重要临床指标。随着 WMH 负荷的增加，结构变化呈离心性扩散。此外，我们发现与 WMH 负荷增加相关的 FA 和 MD 变化有三种主要模式，这表明对白质微观结构有不均匀的影响，在病变附近、深部白质和皮质附近的白质中发现了不同的模式。这项研究还提出了一些关于 WMH 相关病理发生的问题，特别是是否存在一些异常的脑结构和微观结构发现早于 WMH 的出现。我们还发现，与其他研究类似，WMH 的危险因素对 WMH 的解释能力较低，不清楚哪些因素导致了 WMH。
