Greenman Danielle, Bennett Ilana J
Department of Psychology, University of California, Riverside, USA.
Department of Psychology, University of California, Riverside, USA.
Neurobiol Aging. 2025 May;149:34-43. doi: 10.1016/j.neurobiolaging.2025.02.004. Epub 2025 Feb 19.
This study aimed to provide a complete characterization of age group differences in cortical lobar, hippocampal, and subcortical gray matter microstructure using a multi-compartment diffusion-weighted MRI (DWI) approach with parameters optimized for gray matter (Neurite Orientation Dispersion and Density Imaging, NODDI). 76 younger (undergraduate students) and 64 older (surrounding communities) adults underwent diffusion-, T1-, and susceptibility-weighted MRI. Results revealed eight unique patterns across the 12 regions of interest in the relative direction and magnitude of age effects across NODDI metrics, which were grouped into three prominent patterns: cortical gray matter had predominantly higher free diffusion in older than younger adults, the hippocampus and amygdala had predominantly higher dispersion of diffusion and intracellular diffusion in older than younger adults, and the putamen and globus pallidus had lower dispersion of diffusion in older than younger adults. Results remained largely unchanged after controlling for normalized regional volume, suggesting that higher free diffusion in older than younger adults in cortical gray matter was not driven by macrostructural atrophy. Results also remained largely unchanged after controlling for iron content (QSM, R*), even in iron-rich subcortical regions. Taken together, these patterns of age effects across NODDI metrics provide evidence of region-specific neurobiological substrates of aging of gray matter microstructure.
本研究旨在利用多室扩散加权磁共振成像（DWI）方法，通过针对灰质优化的参数（神经突方向离散度和密度成像，NODDI），全面描述皮质叶、海马体和皮质下灰质微观结构在年龄组上的差异。76名年轻成年人（本科生）和64名年长成年人（周边社区居民）接受了扩散加权、T1加权和磁敏感加权磁共振成像检查。结果显示，在NODDI指标中，12个感兴趣区域的年龄效应在相对方向和大小上呈现出8种独特模式，这些模式可分为三种主要模式：皮质灰质中，年长成年人的自由扩散主要高于年轻成年人；海马体和杏仁核中，年长成年人的扩散离散度和细胞内扩散主要高于年轻成年人；壳核和苍白球中，年长成年人的扩散离散度低于年轻成年人。在控制归一化区域体积后，结果基本保持不变，这表明皮质灰质中，年长成年人比年轻成年人具有更高的自由扩散并非由宏观结构萎缩所致。即使在富含铁的皮质下区域，在控制铁含量（定量磁敏感图，R*）后，结果也基本保持不变。综上所述，这些NODDI指标的年龄效应模式为灰质微观结构老化的区域特异性神经生物学基础提供了证据。
