White matter hyperintensities (WMH) are associated with cortical thinning. Although they are primarily detected in older participants, these lesions can appear in younger and midlife individuals. Here, we tested whether WMH are associated with cortical thinning in relatively younger (26–50 years) and relatively older (58–84) participants who were free of dementia, and how these associations are moderated by WMH localization. WMH were automatically quantified and categorized according to the localization of three classes of white matter tracts: association, commissural and projection fibers. Mediation analyses were used to infer whether differences in cortical thickness between younger and older participants were explained by WMH. Our results revealed that total WMH explained between 20.6 % and 65.5 % of the effect of age on cortical thickness in AD-signature regions including the lateral temporal lobes and supramarginal gyrus, among others. This mediation was slightly stronger for projection WMH, although it was still significant for association and commissural WMH. These results suggest that there is an interplay between vascular and AD causes of cognitive impairment that starts at younger ages.

中文翻译：

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中晚年皮质厚度与白质高信号的关系


白质高信号（WMH）与皮质变薄有关。尽管这些病变主要在老年参与者中发现，但这些病变也可能出现在年轻和中年个体中。在这里，我们测试了 WMH 是否与相对年轻（26-50 岁）和相对老年（58-84）无痴呆的参与者的皮质变薄相关，以及这些关联如何通过 WMH 定位来调节。 WMH 根据三类白质束的定位自动量化和分类：联合纤维、连合纤维和投射纤维。中介分析用于推断年轻参与者和老年参与者之间皮质厚度的差异是否由 WMH 解释。我们的结果显示，总 WMH 解释了年龄对 AD 特征区域（包括外侧颞叶和缘上回等）皮质厚度影响的 20.6% 至 65.5%。尽管对于关联和连合 WMH 仍然很重要，但这种中介对于投射 WMH 来说稍强一些。这些结果表明，血管性认知障碍和 AD 病因之间存在相互作用，认知障碍从年轻时就开始出现。